abstract
stringlengths 3
192k
| title
stringlengths 4
857
|
|---|---|
we describe the pycbc search for gravitational waves from compact-object binary coalescences in advanced gravitational-wave detector data. the search was used in the first advanced laser interferometer gravitational-wave observatory (ligo) observing run and unambiguously identified two black hole binary mergers, gw150914 and gw151226. at its core, the pycbc search performs a matched-filter search for binary merger signals using a bank of gravitational-wave template waveforms. we provide a complete description of the search pipeline including the steps used to mitigate the effects of noise transients in the data, identify candidate events and measure their statistical significance. the analysis is able to measure false-alarm rates as low as one per million years, required for confident detection of signals. using data from initial ligo's sixth science run, we show that the new analysis reduces the background noise in the search, giving a 30 % increase in sensitive volume for binary neutron star systems over previous searches. | the pycbc search for gravitational waves from compact binary coalescence |
we present the second public data release of the dark energy survey, des dr2, based on optical/near-infrared imaging by the dark energy camera mounted on the 4 m blanco telescope at cerro tololo inter-american observatory in chile. des dr2 consists of reduced single-epoch and coadded images, a source catalog derived from coadded images, and associated data products assembled from 6 yr of des science operations. this release includes data from the des wide-area survey covering ~5000 deg2 of the southern galactic cap in five broad photometric bands, grizy. des dr2 has a median delivered point-spread function fwhm of g = 1.11″, r = 0.95″, i = 0.88″, z = 0.83″, and y = 0"90, photometric uniformity with a standard deviation of < 3 mmag with respect to gaia dr2 g band, a photometric accuracy of ~11 mmag, and a median internal astrometric precision of ~27 mas. the median coadded catalog depth for a 1"95 diameter aperture at signal-to-noise ratio = 10 is g = 24.7, r = 24.4, i = 23.8, z = 23.1, and y = 21.7 mag. des dr2 includes ~691 million distinct astronomical objects detected in 10,169 coadded image tiles of size 0.534 deg2 produced from 76,217 single-epoch images. after a basic quality selection, benchmark galaxy and stellar samples contain 543 million and 145 million objects, respectively. these data are accessible through several interfaces, including interactive image visualization tools, web-based query clients, image cutout servers, and jupyter notebooks. des dr2 constitutes the largest photometric data set to date at the achieved depth and photometric precision. | the dark energy survey data release 2 |
determining the properties of old stellar populations (those with age >1 gyr) has long involved the comparison of their integrated light, either in the form of photometry or spectroscopic indexes, with empirical or synthetic templates. here we re-evaluate the properties of old stellar populations using a new set of stellar population synthesis models, designed to incorporate the effects of binary stellar evolution pathways as a function of stellar mass and age. we find that single-aged stellar population models incorporating binary stars, as well as new stellar evolution and atmosphere models, can reproduce the colours and spectral indices observed in both globular clusters and quiescent galaxies. the best-fitting model populations are often younger than those derived from older spectral synthesis models and may also lie at slightly higher metallicities. | re-evaluating old stellar populations |
precise and accurate parameters for late-type (late k and m) dwarf stars are important for characterization of any orbiting planets, but such determinations have been hampered by these stars’ complex spectra and dissimilarity to the sun. we exploit an empirically calibrated method to estimate spectroscopic effective temperature (teff) and the stefan-boltzmann law to determine radii of 183 nearby k7-m7 single stars with a precision of 2%-5%. our improved stellar parameters enable us to develop model-independent relations between teff or absolute magnitude and radius, as well as between color and teff. the derived teff-radius relation depends strongly on [fe/h], as predicted by theory. the relation between absolute ks magnitude and radius can predict radii accurate to ≃ 3%. we derive bolometric corrections to the v{{r}c}{{i}c}grizjh{{k}s} and gaia passbands as a function of color, accurate to 1%-3%. we confront the reliability of predictions from dartmouth stellar evolution models using a markov chain monte carlo to find the values of unobservable model parameters (mass, age) that best reproduce the observed effective temperature and bolometric flux while satisfying constraints on distance and metallicity as bayesian priors. with the inferred masses we derive a semi-empirical mass-absolute magnitude relation with a scatter of 2% in mass. the best-agreement models overpredict stellar teff values by an average of 2.2% and underpredict stellar radii by 4.6%, similar to differences with values from low-mass eclipsing binaries. these differences are not correlated with metallicity, mass, or indicators of activity, suggesting issues with the underlying model assumptions, e.g., opacities or convective mixing length. | how to constrain your m dwarf: measuring effective temperature, bolometric luminosity, mass, and radius |
the transiting exoplanet survey satellite (tess) is the first high-precision full-sky photometric survey in space. we extracted light curves from a magnitude limited set of stars and other stationary luminous objects from the tess full frame images using the mit quick look pipeline. here, we describe the techniques used to create light curves. | photometry of 10 million stars from the first two years of tess full frame images: part i |
using 25 years of data from uninterrupted monitoring of stellar orbits in the galactic center, we present an update of the main results from this unique data set: a measurement of mass and distance to sgr a*. our progress is not only due to the eight-year increase in time base, but also to the improved definition of the coordinate system. the star s2 continues to yield the best constraints on the mass of and distance to sgr a* the statistical errors of 0.13× {10}6 {m}⊙and 0.12 kpc have halved compared to the previous study. the s2 orbit fit is robust and does not need any prior information. using coordinate system priors, the star s1 also yields tight constraints on mass and distance. for a combined orbit fit, we use 17 stars, which yields our current best estimates for mass and distance: m=4.28+/- 0.10{| }{stat.}+/- 0.21{| }{sys}× {10}6 {m}⊙and {r}0=8.32+/- 0.07{| }{stat.}+/- 0.14{| }{sys} {kpc}. these numbers are in agreement with the recent determination of r 0 from the statistical cluster parallax. the positions of the mass, of the near-infrared flares from sgr a*, and of the radio source sgr a* agree to within 1 mas. in total, we have determined orbits for 40 stars so far, a sample which consists of 32 stars with randomly oriented orbits and a thermal eccentricity distribution, plus eight stars that we can explicitly show are members of the clockwise disk of young stars, and which have lower-eccentricity orbits. | an update on monitoring stellar orbits in the galactic center |
we study the dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using galex, sdss, and wise photometry calibrated on the herschel atlas. we use a new method of constraining sed fits with infrared luminosity (sed+lir fitting), and parameterized attenuation curves determined with the cigale sed-fitting code. attenuation curve slopes and uv bump strengths are reasonably well constrained independently from one another. we find that {a}λ /{a}v attenuation curves exhibit a very wide range of slopes that are on average as steep as the curve slope of the small magellanic cloud (smc). the slope is a strong function of optical opacity. opaque galaxies have shallower curves—in agreement with recent radiative transfer models. the dependence of slopes on the opacity produces an apparent dependence on stellar mass: more massive galaxies have shallower slopes. attenuation curves exhibit a wide range of uv bump amplitudes, from none to milky way (mw)-like, with an average strength one-third that of the mw bump. notably, local analogs of high-redshift galaxies have an average curve that is somewhat steeper than the smc curve, with a modest uv bump that can be, to first order, ignored, as its effect on the near-uv magnitude is 0.1 mag. neither the slopes nor the strengths of the uv bump depend on gas-phase metallicity. functional forms for attenuation laws are presented for normal star-forming galaxies, high-z analogs, and quiescent galaxies. we release the catalog of associated star formation rates and stellar masses (galex-sdss-wise legacy catalog 2). | dust attenuation curves in the local universe: demographics and new laws for star-forming galaxies and high-redshift analogs |
we present the phangs-muse survey, a programme that uses the muse integral field spectrograph at the eso vlt to map 19 massive (9.4 < log(m⋆/m⊙)< 11.0) nearby (d ≲ 20 mpc) star-forming disc galaxies. the survey consists of 168 muse pointings (1' by 1' each) and a total of nearly 15 × 106 spectra, covering ∼1.5 × 106 independent spectra. phangs-muse provides the first integral field spectrograph view of star formation across different local environments (including galaxy centres, bars, and spiral arms) in external galaxies at a median resolution of 50 pc, better than the mean inter-cloud distance in the ionised interstellar medium. this `cloud-scale' resolution allows detailed demographics and characterisations of h ii regions and other ionised nebulae. phangs-muse further delivers a unique view on the associated gas and stellar kinematics and provides constraints on the star-formation history. the phangs-muse survey is complemented by dedicated alma co(2-1) and multi-band hst observations, therefore allowing us to probe the key stages of the star-formation process from molecular clouds to h ii regions and star clusters. this paper describes the scientific motivation, sample selection, observational strategy, data reduction, and analysis process of the phangs-muse survey. we present our bespoke automated data-reduction framework, which is built on the reduction recipes provided by eso but additionally allows for mosaicking and homogenisation of the point spread function. we further present a detailed quality assessment and a brief illustration of the potential scientific applications of the large set of phangs-muse data products generated by our data analysis framework. the data cubes and analysis data products described in this paper represent the basis for the first phangs-muse public data release and are available in the eso archive and via the canadian astronomy data centre. | the phangs-muse survey. probing the chemo-dynamical evolution of disc galaxies |
the detection of the accelerated expansion of the universe has been one of the major breakthroughs in modern cosmology. several cosmological probes (cosmic microwave background, supernovae type ia, baryon acoustic oscillations) have been studied in depth to better understand the nature of the mechanism driving this acceleration, and they are being currently pushed to their limits, obtaining remarkable constraints that allowed us to shape the standard cosmological model. in parallel to that, however, the percent precision achieved has recently revealed apparent tensions between measurements obtained from different methods. these are either indicating some unaccounted systematic effects, or are pointing toward new physics. following the development of cmb, sne, and bao cosmology, it is critical to extend our selection of cosmological probes. novel probes can be exploited to validate results, control or mitigate systematic effects, and, most importantly, to increase the accuracy and robustness of our results. this review is meant to provide a state-of-art benchmark of the latest advances in emerging "beyond-standard" cosmological probes. we present how several different methods can become a key resource for observational cosmology. in particular, we review cosmic chronometers, quasars, gamma-ray bursts, standard sirens, lensing time-delay with galaxies and clusters, cosmic voids, neutral hydrogen intensity mapping, surface brightness fluctuations, stellar ages of the oldest objects, secular redshift drift, and clustering of standard candles. the review describes the method, systematics, and results of each probe in a homogeneous way, giving the reader a clear picture of the available innovative methods that have been introduced in recent years and how to apply them. the review also discusses the potential synergies and complementarities between the various probes, exploring how they will contribute to the future of modern cosmology. | unveiling the universe with emerging cosmological probes |
we review observations of ultraluminous x-ray sources (ulxs). x-ray spectroscopic and timing studies of ulxs suggest a new accretion state distinct from those seen in galactic stellar-mass black hole binaries. the detection of coherent pulsations indicates the presence of neutron-star accretors in three ulxs and therefore apparently super-eddington luminosities. optical and x-ray line profiles of ulxs and the properties of associated radio and optical nebulae suggest that ulxs produce powerful outflows, also indicative of super-eddington accretion. we discuss models of super-eddington accretion and their relationship to the observed behaviors of ulxs. we review the evidence for intermediate-mass black holes (imbhs) in ulxs. we consider the implications of ulxs for super-eddington accretion in active galactic nuclei, heating of the early universe, and the origin of the black hole binary recently detected via gravitational waves. | ultraluminous x-ray sources |
we report the discovery of eight new milky way companions in ∼ 1800 {{deg}}2 of optical imaging data collected during the first year of the dark energy survey (des). each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. the objects span a wide range of absolute magnitudes (mv from -2.2 to -7.4 {mag}), physical sizes (10-170 {pc}), and heliocentric distances (30-330 {kpc}). based on the low surface brightnesses, large physical sizes, and/or large galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the milky way and/or magellanic clouds. we introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. we also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year des data. | eight new milky way companions discovered in first-year dark energy survey data |
the recent discovery of gw150914, the binary black hole merger detected by advanced ligo, has the potential to revolutionize observational astrophysics. but to fully utilize this new window into the universe, we must compare these new observations to detailed models of binary black hole formation throughout cosmic time. expanding upon our previous work [c. l. rodriguez, m. morscher, b. pattabiraman, s. chatterjee, c.-j. haster, and f. a. rasio, phys. rev. lett. 115, 051101 (2015).], we study merging binary black holes formed in globular clusters using our monte carlo approach to stellar dynamics. we have created a new set of 52 cluster models with different masses, metallicities, and radii to fully characterize the binary black hole merger rate. these models include all the relevant dynamical processes (such as two-body relaxation, strong encounters, and three-body binary formation) and agree well with detailed direct n -body simulations. in addition, we have enhanced our stellar evolution algorithms with updated metallicity-dependent stellar wind and supernova prescriptions, allowing us to compare our results directly to the most recent population synthesis predictions for merger rates from isolated binary evolution. we explore the relationship between a cluster's global properties and the population of binary black holes that it produces. in particular, we derive a numerically calibrated relationship between the merger times of ejected black hole binaries and a cluster's mass and radius. with our improved treatment of stellar evolution, we find that globular clusters can produce a significant population of massive black hole binaries that merge in the local universe. we explore the masses and mass ratios of these binaries as a function of redshift, and find a merger rate of ∼5 gpc-3yr-1 in the local universe, with 80% of sources having total masses from 32 m⊙ to 64 m⊙. under standard assumptions, approximately one out of every seven binary black hole mergers in the local universe will have originated in a globular cluster, but we also explore the sensitivity of this result to different assumptions for binary stellar evolution. if black holes were born with significant natal kicks, comparable to those of neutron stars, then the merger rate of binary black holes from globular clusters would be comparable to that from the field, with approximately 1 /2 of mergers originating in clusters. finally we point out that population synthesis results for the field may also be modified by dynamical interactions of binaries taking place in dense star clusters which, unlike globular clusters, dissolved before the present day. | binary black hole mergers from globular clusters: masses, merger rates, and the impact of stellar evolution |
we investigate the evolution of galaxy gas-phase metallicity (o/h) over the range z = 0-3.3 using samples of ~300 galaxies at z ~ 2.3 and ~150 galaxies at z ~ 3.3 from the mosdef survey. this analysis crucially utilizes different metallicity calibrations at z ~ 0 and z > 1 to account for evolving interstellar medium (ism) conditions. we find significant correlations between o/h and stellar mass (m*) at z ~ 2.3 and z ~ 3.3. the low-mass power-law slope of the mass-metallicity relation (mzr) is remarkably invariant over z = 0-3.3, such that o/h ∝ ${m}_{* }^{0.30}$ at all redshifts in this range. at fixed m*, o/h decreases with increasing redshift as dlog(o/h)/dz = -0.11 ± 0.02. we find no evidence that the fundamental metallicity relation between m*, o/h, and star formation rate evolves out to z ~ 3.3. we employ analytic chemical evolution models to place constraints on the mass and metal loading factors of galactic outflows. the efficiency of metal removal increases toward lower m* at fixed redshift and toward higher redshift at fixed m*. these models suggest that the slope of the mzr is primarily set by the scaling of the outflow metal loading factor with m*, not by the change in gas fraction as a function of m*. the evolution toward lower o/h at fixed m* with increasing redshift is driven by both higher gas fraction (leading to stronger dilution of ism metals) and higher metal removal efficiency. these results suggest that the processes governing the smooth baryonic growth of galaxies via gas flows and star formation hold in the same form over at least the past 12 gyr. * based on data obtained at the w.m. keck observatory, which is operated as a scientific partnership among the california institute of technology, the university of california, and nasa, and was made possible by the generous financial support of the w.m. keck foundation. | the mosdef survey: the evolution of the mass-metallicity relation from z = 0 to z 3.3 |
yearslong time series of high-precision brightness measurements have been assembled for thousands of stars with telescopes operating in space. such data have allowed astronomers to measure the physics of stellar interiors via nonradial oscillations, opening a new avenue to study the stars in the universe. asteroseismology, the interpretation of the characteristics of oscillation modes in terms of the physical properties of the stellar interior, brought entirely new insights in how stars rotate and how they build up their chemistry throughout their evolution. data-driven space asteroseismology has delivered a drastic increase in the reliability of computer models mimicking the evolution of stars born with a variety of masses and metallicities. such models are critical ingredients for modern physics as a whole because they are used throughout various contemporary and multidisciplinary research fields in space science, including the search for life outside the solar system, archaeological studies of the milky way, and the study of single and binary supernova progenitors, among which are future gravitational wave sources. the specific role and potential of asteroseismology for those modern research fields are illustrated. the review concludes with current limitations of asteroseismology and highlights how they can be overcome with ongoing and future large infrastructures for survey astronomy combined with new theoretical research in the era of high-performance computing. this review presents results obtained through major community efforts over the past decade. these breakthroughs were achieved in a collaborative and inclusive spirit that is characteristic of the asteroseismology community. the review's aim is to make this research field accessible to graduate students and readers coming from other fields of physics, with incentives to enjoy and join future applications in this domain of astrophysics. | probing the interior physics of stars through asteroseismology |
gravitational-wave detections provide a novel way to determine the hubble constant1-3, which is the current rate of expansion of the universe. this `standard siren' method, with the absolute distance calibration provided by the general theory of relativity, was used to measure the hubble constant using the gravitational-wave detection of the binary neutron-star merger, gw170817, by the laser interferometer gravitational-wave observatory (ligo) and virgo4, combined with optical identification of the host galaxy5,6 ngc 4993. this independent measurement is of particular interest given the discrepancy between the value of the hubble constant determined using type ia supernovae via the local distance ladder (73.24 ± 1.74 kilometres per second per megaparsec) and the value determined from cosmic microwave background observations (67.4 ± 0.5 kilometres per second per megaparsec): these values differ7,8 by about 3σ. local distance ladder observations may achieve a precision of one per cent within five years, but at present there are no indications that further observations will substantially reduce the existing discrepancies9. here we show that additional gravitational-wave detections by ligo and virgo can be expected to constrain the hubble constant to a precision of approximately two per cent within five years and approximately one per cent within a decade. this is because observing gravitational waves from the merger of two neutron stars, together with the identification of a host galaxy, enables a direct measurement of the hubble constant independent of the systematics associated with other available methods. in addition to clarifying the discrepancy between existing low-redshift (local ladder) and high-redshift (cosmic microwave background) measurements, a precision measurement of the hubble constant is of crucial value in elucidating the nature of dark energy10,11. | a two per cent hubble constant measurement from standard sirens within five years |
information security and authentication are important challenges facing society. recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and development of advanced approaches are necessary to deny unauthorized access to critical data. free space optical technology has been investigated by many researchers in information security, encryption, and authentication. the main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make information encryption more secure and more difficult to attack. this roadmap article presents an overview of the potential, recent advances, and challenges of optical security and encryption using free space optics. the roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. the first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [yamaguchi], the digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [nomura], simultaneous encryption of multiple signals [pérez-cabré], asymmetric methods based on information truncation [nishchal], and dynamic encryption of video sequences [torroba]. asymmetric and one-way cryptosystems are analyzed by peng. the second category is on compression for encryption. in their respective contributions, alfalou and stern propose similar goals involving compressed data and compressive sensing encryption. the very important area of cryptanalysis is the topic of the third category with two sections: sheridan reviews phase retrieval algorithms to perform different attacks, whereas situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. the fourth category with two contributions reports how encryption could be implemented at the nano- or micro-scale. naruse discusses the use of nanostructures in security applications and carnicer proposes encoding information in a tightly focused beam. in the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. in particular, the authors [chen, tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. finally, in the sixth category, mosk and javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication. | roadmap on optical security |
we use the age-metallicity distribution of 96 galactic globular clusters (gcs) to infer the formation and assembly history of the milky way (mw), culminating in the reconstruction of its merger tree. based on a quantitative comparison of the galactic gc population to the 25 cosmological zoom-in simulations of mw-mass galaxies in the e-mosaics project, which self-consistently model the formation and evolution of gc populations in a cosmological context, we find that the mw assembled quickly for its mass, reaching {25, 50} per cent of its present-day halo mass already at z = {3, 1.5} and half of its present-day stellar mass at z = 1.2. we reconstruct the mw's merger tree from its gc age-metallicity distribution, inferring the number of mergers as a function of mass ratio and redshift. these statistics place the mw's assembly rate among the 72th-94th percentile of the e-mosaics galaxies, whereas its integrated properties (e.g. number of mergers, halo concentration) match the median of the simulations. we conclude that the mw has experienced no major mergers (mass ratios >1:4) since z ∼ 4, sharpening previous limits of z ∼ 2. we identify three massive satellite progenitors and constrain their mass growth and enrichment histories. two are proposed to correspond to sagittarius (a few 108 m⊙) and the gcs formerly associated with canis major (∼ 10^9 m_⊙). the third satellite has no known associated relic and was likely accreted between z = 0.6 and 1.3. we name this enigmatic galaxy kraken and propose that it is the most massive satellite (m_*∼ 2× 10^9 m_⊙) ever accreted by the mw. we predict that ∼40 per cent of the galactic gcs formed ex situ (in galaxies with masses m* = 2 × 107-2× 10^9 m_⊙), with 6 ± 1 being former nuclear clusters. | the formation and assembly history of the milky way revealed by its globular cluster population |
accretion through circumstellar disks plays an important role in star formation and in establishing the properties of the regions in which planets form and migrate. the mechanisms by which protostellar and protoplanetary disks accrete onto low-mass stars are not clear; angular momentum transport by magnetic fields is thought to be involved, but the low-ionization conditions in major regions of protoplanetary disks lead to a variety of complex nonideal magnetohydrodynamic effects whose implications are not fully understood. accretion in pre-main-sequence stars of masses ≲1m⊙ (and in at least some 2-3-m⊙ systems) is generally funneled by the stellar magnetic field, which disrupts the disk at scales typically of order a few stellar radii. matter moving at near free-fall velocities shocks at the stellar surface; the resulting accretion luminosities from the dissipation of kinetic energy indicate that mass addition during the t tauri phase over the typical disk lifetime ∼3 myr is modest in terms of stellar evolution, but is comparable to total disk reservoirs as estimated from millimeter-wave dust emission (∼10-2 m⊙). pre-main-sequence accretion is not steady, encompassing timescales ranging from approximately hours to a century, with longer-timescale variations tending to be the largest. accretion during the protostellar phase—while the protostellar envelope is still falling onto the disk—is much less well understood, mostly because the properties of the central obscured protostar are difficult to estimate. kinematic measurements of protostellar masses with new interfometric facilities should improve estimates of accretion rates during the earliest phases of star formation. | accretion onto pre-main-sequence stars |
the first jwst spectroscopy of the luminous galaxy gn-z11 simultaneously both established its redshift at $z=10.6$ and revealed a rest-ultraviolet spectrum dominated by signatures of highly-ionized nitrogen, which has so far defied clear interpretation. here we present a reappraisal of this spectrum in the context of both detailed nebular modeling and nearby metal-poor reference galaxies. the n iv] emission enables the first nebular density measurement in a star-forming galaxy at $z>10$, and reveals evidence for extremely high densities $n_e\gtrsim 10^5$ $\mathrm{cm^{-3}}$. we definitively establish with a suite of photoionization models that regardless of ionization mechanism and accounting for depletion and this density enhancement, an ism substantially enriched in nitrogen ($[\mathrm{n/o}]=+0.52$) is required to reproduce the observed lines. a search of local uv databases confirms that nearby metal-poor galaxies power n iv] emission, but that this emission is uniformly associated with lower densities than implied in gn-z11. we compare to a unique nearby galaxy, mrk~996, where a high concentration of wolf-rayet stars and their cno-processed wind ejecta produce a uv spectrum remarkably similar to that of both gn-z11 and the lyc-leaking super star cluster in the sunburst arc. collating this evidence in the context of galactic stellar abundances, we suggest that the peculiar nitrogenic features prominent in gn-z11 may be a unique signature of intense and densely clustered star formation in the evolutionary chain of the present-day globular clusters, consistent with in-situ early enrichment with nuclear-processed stellar ejecta on a massive scale. combined with insight from local galaxies, these and future jwst data open a powerful new window onto the physical conditions of star formation and chemical enrichment at the highest redshifts. | gn-z11 in context: possible signatures of globular cluster precursors at redshift 10 |
this review examines the state-of-the-art knowledge of high-mass star and massive cluster formation, gained from ambitious observational surveys, which acknowledges the multiscale characteristics of these processes. after a brief overview of theoretical models and main open issues, we present observational searches for the evolutionary phases of high-mass star formation, first among high-luminosity sources and more recently among young massive protostars and the elusive high-mass prestellar cores. we then introduce the most likely evolutionary scenario for high-mass star formation, which emphasizes the link of high-mass star formation to massive cloud and cluster formation. finally, we introduce the first attempts to search for variations of the star-formation activity and cluster formation in molecular cloud complexes in the most extreme star-forming sites and across the milky way. the combination of galactic plane surveys and high-angular resolution images with submillimeter facilities such as atacama large millimeter array (alma) are prerequisites to make significant progress in the forthcoming decade. | high-mass star and massive cluster formation in the milky way |
rayleigh's criterion for resolving two incoherent point sources has been the most influential measure of optical imaging resolution for over a century. in the context of statistical image processing, violation of the criterion is especially detrimental to the estimation of the separation between the sources, and modern far-field superresolution techniques rely on suppressing the emission of close sources to enhance the localization precision. using quantum optics, quantum metrology, and statistical analysis, here we show that, even if two close incoherent sources emit simultaneously, measurements with linear optics and photon counting can estimate their separation from the far field almost as precisely as conventional methods do for isolated sources, rendering rayleigh's criterion irrelevant to the problem. our results demonstrate that superresolution can be achieved not only for fluorophores but also for stars. | quantum theory of superresolution for two incoherent optical point sources |
we have constructed merger trees for galaxies in the illustris simulation by directly tracking the baryonic content of subhaloes. these merger trees are used to calculate the galaxy-galaxy merger rate as a function of descendant stellar mass, progenitor stellar mass ratio, and redshift. we demonstrate that the most appropriate definition for the mass ratio of a galaxy-galaxy merger consists in taking both progenitor masses at the time when the secondary progenitor reaches its maximum stellar mass. additionally, we avoid effects from `orphaned' galaxies by allowing some objects to `skip' a snapshot when finding a descendant, and by only considering mergers which show a well-defined `infall' moment. adopting these definitions, we obtain well-converged predictions for the galaxy-galaxy merger rate with the following main features, which are qualitatively similar to the halo-halo merger rate except for the last one: a strong correlation with redshift that evolves as ∼(1 + z)2.4-2.8, a power law with respect to mass ratio, and an increasing dependence on descendant stellar mass, which steepens significantly for descendant stellar masses greater than ∼2 × 1011 m⊙. these trends are consistent with observational constraints for medium-sized galaxies (m* ≳ 1010 m⊙), but in tension with some recent observations of the close pair fraction for massive galaxies (m* ≳ 1011 m⊙), which report a nearly constant or decreasing evolution with redshift. finally, we provide a fitting function for the galaxy-galaxy merger rate which is accurate over a wide range of stellar masses, progenitor mass ratios, and redshifts. | the merger rate of galaxies in the illustris simulation: a comparison with observations and semi-empirical models |
we have updated the munich galaxy formation model to the planck first-year cosmology, while modifying the treatment of baryonic processes to reproduce recent data on the abundance and passive fractions of galaxies from z = 3 down to z = 0. matching these more extensive and more precise observational results requires us to delay the reincorporation of wind ejecta, to lower the surface density threshold for turning cold gas into stars, to eliminate ram-pressure stripping in haloes less massive than {∼ }10^{14}{ m_{⊙}}, and to modify our model for radio mode feedback. these changes cure the most obvious failings of our previous models, namely the overly early formation of low-mass galaxies and the overly large fraction of them that are passive at late times. the new model is calibrated to reproduce the observed evolution both of the stellar mass function and of the distribution of star formation rate at each stellar mass. massive galaxies (log m⋆/m⊙ ≥ 11.0) assemble most of their mass before z = 1 and are predominantly old and passive at z = 0, while lower mass galaxies assemble later and, for log m⋆/m⊙ ≤ 9.5, are still predominantly blue and star forming at z = 0. this phenomenological but physically based model allows the observations to be interpreted in terms of the efficiency of the various processes that control the formation and evolution of galaxies as a function of their stellar mass, gas content, environment and time. | galaxy formation in the planck cosmology - i. matching the observed evolution of star formation rates, colours and stellar masses |
using a sample of 69,919 red giants from the sdss-iii/apogee data release 12, we measure the distribution of stars in the [α/fe] versus [fe/h] plane and the metallicity distribution functions (mdfs) across an unprecedented volume of the milky way disk, with radius 3 < r < 15 kpc and height | z| \lt 2 kpc. stars in the inner disk (r < 5 kpc) lie along a single track in [α/fe] versus [fe/h], starting with α-enhanced, metal-poor stars and ending at [α/fe] ∼ 0 and [fe/h] ∼ +0.4. at larger radii we find two distinct sequences in [α/fe] versus [fe/h] space, with a roughly solar-α sequence that spans a decade in metallicity and a high-α sequence that merges with the low-α sequence at super-solar [fe/h]. the location of the high-α sequence is nearly constant across the disk however, there are very few high-α stars at r > 11 kpc. the peak of the midplane mdf shifts to lower metallicity at larger r, reflecting the galactic metallicity gradient. most strikingly, the shape of the midplane mdf changes systematically with radius, from a negatively skewed distribution at 3 < r < 7 kpc, to a roughly gaussian distribution at the solar annulus, to a positively skewed shape in the outer galaxy. for stars with | z| \gt 1 kpc or [α/fe] > 0.18, the mdf shows little dependence on r. the positive skewness of the outer-disk mdf may be a signature of radial migration; we show that blurring of stellar populations by orbital eccentricities is not enough to explain the reversal of mdf shape, but a simple model of radial migration can do so. | chemical cartography with apogee: metallicity distribution functions and the chemical structure of the milky way disk |
we determine the milky way (mw) mass profile inferred from fitting physically motivated models to the gaia dr2 galactic rotation curve and other data. using various hydrodynamical simulations of mw-mass haloes, we show that the presence of baryons induces a contraction of the dark matter (dm) distribution in the inner regions, r ≲ 20 kpc. we provide an analytic expression that relates the baryonic distribution to the change in the dm halo profile. for our galaxy, the contraction increases the enclosed dm halo mass by factors of roughly 1.3, 2, and 4 at radial distances of 20, 8, and 1 kpc, respectively compared to an uncontracted halo. ignoring this contraction results in systematic biases in the inferred halo mass and concentration. we provide a best-fitting contracted nfw halo model to the mw rotation curve that matches the data very well.1 the best-fit has a dm halo mass, $m_{200}^{\rm dm}=0.97_{-0.19}^{+0.24}\times 10^{12}\,\mathrm{m}_\odot$ , and concentration before baryon contraction of $9.4_{-2.6}^{+1.9}$ , which lie close to the median halo mass-concentration relation predicted in λcdm. the inferred total mass, $m_{200}^{\rm total}=1.08_{-0.14}^{+0.20} \times 10^{12}\,\mathrm{m}_\odot$ , is in good agreement with recent measurements. the model gives an mw stellar mass of $5.04_{-0.52}^{+0.43}\times 10^{10}\,\mathrm{m}_\odot$ and infers that the dm density at the solar position is $\rho _{\odot }^{\rm dm}=8.8_{-0.5}^{+0.5}\times 10^{-3}\,\mathrm{m}_\odot \,\mathrm{pc}^{-3}\equiv 0.33_{-0.02}^{+0.02}\,\rm {gev}\,\rm {cm}^{-3}$ . the rotation curve data can also be fitted with an uncontracted nfw halo model, but with very different dm and stellar parameters. the observations prefer the physically motivated contracted nfw halo, but the measurement uncertainties are too large to rule out the uncontracted nfw halo. | the milky way total mass profile as inferred from gaia dr2 |
context. the astrophysical characterisation of sources is among the major new data products in the third gaia data release (dr3). in particular, there are stellar parameters for 471 million sources estimated from low-resolution bp/rp spectra.aims: we present the general stellar parameterizer from photometry (gsp-phot), which is part of the astrophysical parameters inference system (apsis). gsp-phot is designed to produce a homogeneous catalogue of parameters for hundreds of millions of single non-variable stars based on their astrometry, photometry, and low-resolution bp/rp spectra. these parameters are effective temperature, surface gravity, metallicity, absolute mg magnitude, radius, distance, and extinction for each star.methods: gsp-phot uses a bayesian forward-modelling approach to simultaneously fit the bp/rp spectrum, parallax, and apparent g magnitude. a major design feature of gsp-phot is the use of the apparent flux levels of bp/rp spectra to derive, in combination with isochrone models, tight observational constraints on radii and distances. we carefully validate the uncertainty estimates by exploiting repeat gaia observations of the same source.results: the data release includes gsp-phot results for 471 million sources with g < 19. typical differences to literature values are 110 k for teff and 0.2-0.25 for log g, but these depend strongly on data quality. in particular, gsp-phot results are significantly better for stars with good parallax measurements (ϖ/σϖ > 20), mostly within 2 kpc. metallicity estimates exhibit substantial biases compared to literature values and are only useful at a qualitative level. however, we provide an empirical calibration of our metallicity estimates that largely removes these biases. extinctions a0 and abp show typical differences from reference values of 0.07-0.09 mag. mcmc samples of the parameters are also available for 95% of the sources.conclusions: gsp-phot provides a homogeneous catalogue of stellar parameters, distances, and extinctions that can be used for various purposes, such as sample selections (ob stars, red giants, solar analogues etc.). in the context of asteroseismology or ground-based interferometry, where targets are usually bright and have good parallax measurements, gsp-phot results should be particularly useful for combined analysis or target selection. | gaia data release 3. analysis of the gaia bp/rp spectra using the general stellar parameterizer from photometry |
this is an exciting time for the study of r-process nucleosynthesis. recently, a neutron star merger gw170817 was observed in extraordinary detail with gravitational waves and electromagnetic radiation from radio to γ rays. the very red color of the associated kilonova suggests that neutron star mergers are an important r-process site. astrophysical simulations of neutron star mergers and core collapse supernovae are making rapid progress. detection of both electron neutrinos and antineutrinos from the next galactic supernova will constrain the composition of neutrino-driven winds and provide unique nucleosynthesis information. finally, frib and other rare-isotope beam facilities will soon have dramatic new capabilities to synthesize many neutron-rich nuclei that are involved in the r-process. the new capabilities can significantly improve our understanding of the r-process and likely resolve one of the main outstanding problems in classical nuclear astrophysics. however, to make best use of the new experimental capabilities and to fully interpret the results, a great deal of infrastructure is needed in many related areas of astronomy, astrophysics, and nuclear theory. we place these experiments in context by discussing astrophysical simulations and observations of r-process sites, observations of stellar abundances, galactic chemical evolution, and nuclear theory for the structure and reactions of very neutron-rich nuclei. this review paper was initiated at a three-week international collaborations in nuclear theory program in june 2016, where we explored promising r-process experiments and discussed their likely impact, and their astronomical, astrophysical, and nuclear theory context. | r-process nucleosynthesis: connecting rare-isotope beam facilities with the cosmos |
the spin of a black hole is an important quantity to study, providing a window into the processes by which a black hole was born and grew. furthermore, spin can be a potent energy source for powering relativistic jets and energetic particle acceleration. in this review, i describe the techniques currently used to detect and measure the spins of black holes. it is shown that: two well-understood techniques, x-ray reflection spectroscopy and thermal continuum fitting, can be used to measure the spins of black holes that are accreting at moderate rates. there is a rich set of other electromagnetic techniques allowing us to extend spin measurements to lower accretion rates. many accreting supermassive black holes are found to be rapidly spinning, although a population of more slowly spinning black holes emerges at masses above as expected from recent structure formation models. many accreting stellar-mass black holes in x-ray binary systems are rapidly spinning and must have been born in this state. the advent of gravitational wave astronomy has enabled the detection of spin effects in merging binary black holes. most of the premerger black holes are found to be slowly spinning, a notable exception being an object that may itself be a merger product. the stark difference in spins between the black hole x-ray binary and the binary black hole populations shows that there is a diversity of formation mechanisms.given the array of new electromagnetic and gravitational wave capabilities currently being planned, the future of black hole spin studies is bright. | observational constraints on black hole spin |
in this study, we use simple performance metrics to assess the science capabilities of future ground-based gravitational-wave detector networks -- composed of a+ or voyager upgrades to the ligo, virgo, and kagra observatories and proposed next generation observatories such as cosmic explorer and einstein telescope. these metrics refer to coalescences of binary neutron stars (bnss) and binary black holes (bbhs) and include: (i) network detection efficiency and detection rate of cosmological sources as a function of redshift, (ii) signal-to-noise ratios and the accuracy with which intrinsic and extrinsic parameters would be measured, and (iii) enabling multimessenger astronomy with gravitational waves by accurate 3d localization and early warning alerts. we further discuss the science enabled by the small population of rare and extremely loud events. while imminent upgrades will provide impressive advances in all these metrics, next generation observatories will deliver an improvement of an order-of-magnitude or more in most metrics. in fact, a network containing two or three such facilities will detect half of all the bns and bbh mergers up to a redshift of $z=1$ and $z=20$, respectively, give access to hundreds of bnss and ten thousand bbhs with signal-to-noise ratios exceeding 100, readily localize hundreds to thousands of mergers to within $1\,{\rm deg^2}$ on the sky and better than 10% in luminosity distance, respectively, and consequently, enable mutlimessenger astronomy through follow-up surveys in the electromagnetic spectrum several times a week. such networks will further shed light on potential cosmological merger populations and detect an abundance of high-fidelity bns and bbh signals which will allow investigations of the high-density regime of matter at an unprecedented level and enable precision tests of general relativity in the strong-filed regime, respectively. | listening to the universe with next generation ground-based gravitational-wave detectors |
the distribution of dark matter halo masses can be accurately predicted in the lambda cold dark matter (λcdm) cosmology. the presence of a single massive halo or galaxy at a particular redshift, assuming some baryon and stellar fraction for the latter, can therefore be used to test the underlying cosmological model. a number of recent measurements of very large galaxy stellar masses at high redshift (z > 8) motivate an investigation into whether any of these objects are in tension with λcdm. we use extreme value statistics to generate confidence regions in the mass-redshift plane for the most extreme mass haloes and galaxies. tests against numerical models show no tension, neither in their dark matter halo masses nor their galaxy stellar masses. however, we find tentative >3σ tension with recent observational determinations of galaxy masses at high redshift from both hubble space telescope and james webb space telescope, despite using conservative estimates for the stellar fraction (f⋆ ~ 1). either these galaxies are in tension with λcdm, or there are unaccounted for uncertainties in their stellar mass or redshift estimates. | extreme value statistics of the halo and stellar mass distributions at high redshift: are jwst results in tension with λcdm? |
context. the interaction of the light from astronomical objects with the constituents of the earth's atmosphere leads to the formation of telluric absorption lines in ground-based collected spectra. correcting for these lines, mostly affecting the red and infrared region of the spectrum, usually relies on observations of specific stars obtained close in time and airmass to the science targets, therefore using precious observing time.aims: we present molecfit, a tool to correct for telluric absorption lines based on synthetic modelling of the earth's atmospheric transmission. molecfit is versatile and can be used with data obtained with various ground-based telescopes and instruments.methods: molecfit combines a publicly available radiative transfer code, a molecular line database, atmospheric profiles, and various kernels to model the instrument line spread function. the atmospheric profiles are created by merging a standard atmospheric profile representative of a given observatory's climate, of local meteorological data, and of dynamically retrieved altitude profiles for temperature, pressure, and humidity. we discuss the various ingredients of the method, its applicability, and its limitations. we also show examples of telluric line correction on spectra obtained with a suite of eso very large telescope (vlt) instruments.results: compared to previous similar tools, molecfit takes the best results for temperature, pressure, and humidity in the atmosphere above the observatory into account. as a result, the standard deviation of the residuals after correction of unsaturated telluric lines is frequently better than 2% of the continuum.conclusions: molecfit is able to accurately model and correct for telluric lines over a broad range of wavelengths and spectral resolutions. the accuracy reached is comparable to or better than the typical accuracy achieved using a telluric standard star observation. the availability of such a general tool for telluric absorption correction may improve future observational and analysing strategies, as well as empower users of archival data. molecfit is available at http://www.eso.org/pipelines/skytoolsbased on observations made with eso telescopes at the la silla paranal observatory under programme ids: 60.a-9100, 60.a-9452, 076.c-0129, 075.a-0603, 079.d-0374, 080.d-0526, 290.c-5022, 092.d-0024, 084.d-0912, 085.d-0161, 086.d-0066, and 088.d-0109. | molecfit: a general tool for telluric absorption correction. i. method and application to eso instruments |
using three-dimensional simulations, we study the dynamics and final structure of merging solitonic cores predicted to form in ultralight axion dark matter halos. the classical, newtonian equations of motion of a self-gravitating scalar field are described by the schrödinger-poisson equations. we investigate mergers of ground state (boson star) configurations with varying mass ratios, relative phases, orbital angular momenta and initial separation with the primary goal to understand the mass loss of the emerging core by gravitational cooling. previous results showing that the final density profiles have solitonic cores and navarro-frenk-white-like tails are confirmed. in binary mergers, the final core mass does not depend on initial phase difference or angular momentum and only depends on mass ratio, total initial mass, and total energy of the system. for nonzero angular momenta, the otherwise spherical cores become rotating ellipsoids. the results for mergers of multiple cores are qualitatively identical. | simulations of solitonic core mergers in ultralight axion dark matter cosmologies |
we present a new generation of substellar atmosphere and evolution models, appropriate for application to studies of l-, t-, and y-type brown dwarfs and self-luminous extrasolar planets. the models describe the expected temperature-pressure profiles and emergent spectra of atmospheres in radiative-convective equilibrium with effective temperatures and gravities within the ranges 200 ≤ teff ≤ 2400 k and $2.5\leqslant \mathrm{log}g\leqslant 5.5$ . these ranges encompass masses from about 0.5 to 85 jupiter masses for a set of metallicities ([m/h] = - 0.5 to + 0.5), c/o ratios (from 0.5 to 1.5 times that of solar), and ages. these models expand the diversity of model atmospheres currently available, notably to cooler effective temperatures and greater ranges in c/o. notable improvements from past such models include updated opacities and atmospheric chemistry. here we describe our modeling approach and present our initial tranche of models for cloudless, chemical equilibrium atmospheres. we compare the modeled spectra, photometry, and evolution to various data sets. | the sonora brown dwarf atmosphere and evolution models. i. model description and application to cloudless atmospheres in rainout chemical equilibrium |
tianqin is a planned space-based gravitational wave (gw) observatory consisting of three earth-orbiting satellites with an orbital radius of about $10^5 \, {\rm km}$. the satellites will form an equilateral triangle constellation the plane of which is nearly perpendicular to the ecliptic plane. tianqin aims to detect gws between $10^{-4} \, {\rm hz}$ and $1 \, {\rm hz}$ that can be generated by a wide variety of important astrophysical and cosmological sources, including the inspiral of galactic ultra-compact binaries, the inspiral of stellar-mass black hole binaries, extreme mass ratio inspirals, the merger of massive black hole binaries, and possibly the energetic processes in the very early universe and exotic sources such as cosmic strings. in order to start science operations around 2035, a roadmap called the 0123 plan is being used to bring the key technologies of tianqin to maturity, supported by the construction of a series of research facilities on the ground. two major projects of the 0123 plan are being carried out. in this process, the team has created a new-generation $17 \, {\rm cm}$ single-body hollow corner-cube retro-reflector which was launched with the queqiao satellite on 21 may 2018; a new laser-ranging station equipped with a $1.2 \, {\rm m}$ telescope has been constructed and the station has successfully ranged to all five retro-reflectors on the moon; and the tianqin-1 experimental satellite was launched on 20 december 2019-the first-round result shows that the satellite has exceeded all of its mission requirements. | the tianqin project: current progress on science and technology |
context. feedback from accreting supermassive black holes (smbhs) is often identified as the main mechanism responsible for regulating star formation in active galactic nucleus (agn) host galaxies. however, the relationships between agn activity, radiation, winds, and star formation are complex and still far from being understood.aims: we study scaling relations between agn properties, host galaxy properties, and agn winds. we then evaluate the wind mean impact on the global star formation history, taking into account the short agn duty cycle with respect to that of star formation.methods: we first collect agn wind observations for 94 agn with detected massive winds at sub-pc to kpc spatial scales. we then fold agn wind scaling relations with agn luminosity functions, to evaluate the average agn wind mass-loading factor as a function of cosmic time.results: we find strong correlations between the agn molecular and ionised wind mass outflow rates and the agn bolometric luminosity. the power law scaling is steeper for ionised winds (slope 1.29 ± 0.38) than for molecular winds (0.76 ± 0.06), meaning that the two rates converge at high bolometric luminosities. the molecular gas depletion timescale and the molecular gas fraction of galaxies hosting powerful agn driven winds are 3-10 times shorter and smaller than those of main sequence galaxies with similar star formation rate (sfr), stellar mass, and redshift. these findings suggest that, at high agn bolometric luminosity, the reduced molecular gas fraction may be due to the destruction of molecules by the wind, leading to a larger fraction of gas in the atomic ionised phase. the agn wind mass-loading factor η = ṁof/sfr is systematically higher than that of starburst driven winds.conclusions: our analysis shows that agn winds are, on average, powerful enough to clean galaxies from their molecular gas only in massive systems at z ≲ 2, i.e. a strong form of co-evolution between smbhs and galaxies appears to break down for the least massive galaxies. | agn wind scaling relations and the co-evolution of black holes and galaxies |
context. the census of stellar and substellar companions of nearby stars is largely incomplete, in particular toward the low-mass brown dwarf and long-period exoplanets. it is, however, fundamentally important in the understanding of the stellar and planetary formation and evolution mechanisms. nearby stars are particularly favorable targets for high precision astrometry.aims: we aim to characterize the presence of physical companions of stellar and substellar mass in orbit around nearby stars.methods: orbiting secondary bodies influence the proper motion of their parent star through their gravitational reflex motion. using the hipparcos and gaia's second data release (gdr2) catalogs, we determined the long-term proper motion of the stars common to these two catalogs. we then searched for a proper motion anomaly (pma) between the long-term proper motion vector and the gdr2 (or hipparcos) measurements, indicative of the presence of a perturbing secondary object. we focussed our analysis on the 6741 nearby stars located within 50 pc, and we also present a catalog of the pma for ≳99% of the hipparcos catalog (≈117 000 stars).results: 30% of the stars studied present a pma greater than 3σ. the pma allows us to detect orbiting companions, or set stringent limits on their presence. we present a few illustrations of the pma analysis to interesting targets. we set upper limits of 0.1-0.3 mj to potential planets orbiting proxima between 1 and 10 au (porb = 3 to 100 years). we confirm that proxima is gravitationally bound to α cen. we recover the masses of the known companions of ɛ eri, ɛ ind, ross 614 and β pic. we also detect the signature of a possible planet of a few jovian masses orbiting τ ceti.conclusions: based on only 22 months of data, the gdr2 has limitations. but its combination with the hipparcos catalog results in very high accuracy pma vectors, that already enable us to set valuable constraints on the binarity of nearby objects. the detection of tangential velocity anomalies at a median accuracy of σ(δvt) = 1.0 m s-1 per parsec of distance is already possible with the gdr2. this type of analysis opens the possibility to identify long period orbital companions otherwise inaccessible. for long orbital periods, gaia's complementarity to radial velocity and transit techniques (that are more sensitive to short orbital periods) already appears to be remarkably powerful. full tables 1 and 2 are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/623/a72 | stellar and substellar companions of nearby stars from gaia dr2. binarity from proper motion anomaly |
merging binaries of neutron-stars are not only strong sources of gravitational waves, but also have the potential of revealing states of matter at densities and temperatures not accessible in laboratories. a crucial and long-standing question in this context is whether quarks are deconfined as a result of the dramatic increase in density and temperature following the merger. we present the first fully general-relativistic simulations of merging neutron-stars including quarks at finite temperatures that can be switched off consistently in the equation of state. within our approach, we can determine clearly what signatures a quark-hadron phase transition would leave in the gravitational-wave signal. we show that if after the merger the conditions are met for a phase transition to take place at several times nuclear saturation density, they would lead to a postmerger signal considerably different from the one expected from the inspiral, that can only probe the hadronic part of the equations of state, and to an anticipated collapse of the merged object. we also show that the phase transition leads to a very hot and dense quark core that, when it collapses to a black hole, produces a ringdown signal different from the hadronic one. finally, in analogy with what is done in heavy-ion collisions, we use the evolution of the temperature and density in the merger remnant to illustrate the properties of the phase transition in a qcd phase diagram. | signatures of quark-hadron phase transitions in general-relativistic neutron-star mergers |
simple generic extensions of isotropic durgapal-fuloria stars to the anisotropic domain are presented. these anisotropic solutions are obtained by guided minimal deformations over the isotropic system. when the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors by means of the minimal geometric deformation approach are satisfied. hence the anisotropic field equations are isolated resulting a more treatable set. the simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. later on, observational effects of such anisotropies when measuring the surface redshift are discussed. to conclude, the consistency of the application of the method over the obtained anisotropic configurations is shown. in this manner, different anisotropic sectors can be isolated of each other and modeled in a simple and systematic way. | gravitational decoupled anisotropies in compact stars |
scaling relations between central black hole (bh) mass and host galaxy properties are of fundamental importance to studies of bh and galaxy evolution throughout cosmic time. here we investigate the relationship between bh mass and host galaxy total stellar mass using a sample of 262 broad-line active galactic nuclei (agns) in the nearby universe (z < 0.055), as well as 79 galaxies with dynamical bh masses. the vast majority of our agn sample is constructed using sloan digital sky survey spectroscopy and searching for seyfert-like narrow-line ratios and broad hα emission. bh masses are estimated using standard virial techniques. we also include a small number of dwarf galaxies with total stellar masses mstellar ≲ 109.5 m⊙ and a subsample of the reverberation-mapped agns. total stellar masses of all 341 galaxies are calculated in the most consistent manner feasible using color-dependent mass-to-light ratios. we find a clear correlation between bh mass and total stellar mass for the agn host galaxies, with mbh ∝ mstellar, similar to that of early-type galaxies with dynamically detected bhs. however, the relation defined by the agns has a normalization that is lower by more than an order of magnitude, with a bh-to-total stellar mass fraction of mbh/mstellar ∼ 0.025% across the stellar mass range 108 ≤ mstellar/m⊙ ≤ 1012. this result has significant implications for studies at high redshift and cosmological simulations in which stellar bulges cannot be resolved. | relations between central black hole mass and total galaxy stellar mass in the local universe |
we present a blind time-delay strong lensing (tdsl) cosmographic analysis of the doubly imaged quasar sdss 1206+4332 . we combine the relative time delay between the quasar images, hubble space telescope imaging, the keck stellar velocity dispersion of the lensing galaxy, and wide-field photometric and spectroscopic data of the field to constrain two angular diameter distance relations. the combined analysis is performed by forward modelling the individual data sets through a bayesian hierarchical framework, and it is kept blind until the very end to prevent experimenter bias. after unblinding, the inferred distances imply a hubble constant h0 = 68.8^{+5.4}_{-5.1} km s-1 mpc-1, assuming a flat λ cold dark matter cosmology with uniform prior on ωm in [0.05, 0.5]. the precision of our cosmographic measurement with the doubly imaged quasar sdss 1206+4332 is comparable with those of quadruply imaged quasars and opens the path to perform on selected doubles the same analysis as anticipated for quads. our analysis is based on a completely independent lensing code than our previous three h0licow systems and the new measurement is fully consistent with those. we provide the analysis scripts paired with the publicly available software to facilitate independent analysis (footnote with link to www.h0licow.org). the consistency between blind measurements with independent codes provides an important sanity check on lens modelling systematics. by combining the likelihoods of the four systems under the same prior, we obtain h0 = 72.5^{+2.1}_{-2.3} km s-1 mpc-1. this measurement is independent of the distance ladder and other cosmological probes. | h0licow - ix. cosmographic analysis of the doubly imaged quasar sdss 1206+4332 and a new measurement of the hubble constant |
accurate knowledge of the thermodynamic properties of zero-temperature, high-density quark matter plays an integral role in attempts to constrain the behavior of the dense qcd matter found inside neutron-star cores, irrespective of the phase realized inside the stars. in this letter, we consider the weak-coupling expansion of the dense qcd equation of state and compute the next-to-next-to-next-to-leading-order contribution arising from the non-abelian interactions among long-wavelength, dynamically screened gluonic fields. accounting for these interactions requires an all-loop resummation, which can be performed using hard-thermal-loop (htl) kinematic approximations. concretely, we perform a full two-loop computation using the htl effective theory, valid for the long-wavelength, or soft, modes. we find that the soft sector is well behaved within cold quark matter, contrary to the case encountered at high temperatures, and find that the new contribution decreases the renormalization-scale dependence of the equation of state at high density. | soft interactions in cold quark matter |
we present a catalogue of white dwarf candidates selected from gaia early data release 3 (edr3). we applied several selection criteria in absolute magnitude, colour, and gaia quality flags to remove objects with unreliable measurements while preserving most stars compatible with the white dwarf locus in the hertzsprung-russell diagram. we then used a sample of over 30 000 spectroscopically confirmed white dwarfs and contaminants from the sloan digital sky survey (sdss) to map the distribution of these objects in the gaia absolute magnitude-colour space. finally, we adopt the same method presented in our previous work on gaia data release 2 (dr2) to calculate a probability of being a white dwarf (pwd) for ≃1.3 million sources that passed our quality selection. the pwd values can be used to select a sample of ${\simeq} 359\,000$ high-confidence white dwarf candidates. we calculated stellar parameters (effective temperature, surface gravity, and mass) for all these stars by fitting gaia astrometry and photometry with synthetic pure-h, pure-he, and mixed h-he atmospheric models. we estimate an upper limit of 93 per cent for the overall completeness of our catalogue for white dwarfs with g ≤ 20 mag and effective temperature (teff) > 7000 k, at high galactic latitudes (|b| > 20°). alongside the main catalogue we include a reduced proper motion extension containing ${\simeq} 10\,200$ white dwarf candidates with unreliable parallax measurements that could, however, be identified on the basis of their proper motion. we also performed a cross-match of our catalogues with sdss data release 16 (dr16) spectroscopy and provide spectral classification based on visual inspection for all resulting matches. | a catalogue of white dwarfs in gaia edr3 |
a precise interstellar dust extinction law is critically important to interpret observations. there are two indicators of extinction: the color excess ratio (cer) and the relative extinction. compared to the cer, the wavelength-dependent relative extinction is more challenging to be determined. in this work, we combine spectroscopic, astrometric, and photometric data to derive high-precision cers and relative extinction from optical to mid-infrared (ir) bands. a group of 61,111 red clump (rc) stars are selected as tracers by stellar parameters from the apache point observatory galaxy evolution experiment survey. the multiband photometric data are collected from gaia, apass, sloan digital sky survey, pan-starrs1, two micron all sky survey, and wide-field infrared survey explorer surveys. for the first time, we calibrate the curvature of cers in determining cers e(λ - g rp)/e(g bp - g rp) from color excess-color excess diagrams. through elaborate uncertainty analysis, we conclude that the precision of our cers is significantly improved (σ < 0.015). with parallaxes from gaia dr2, we calculate the relative extinction {a}{gbp}}/{a}{grp}} for 5051 rc stars. by combining the cers with the {a}{gbp}}/{a}{grp}}, the optical-mid-ir extinction aλ /{a}{grp}} has been determined in a total of 21 bands. given no bias toward any specific environment, our extinction law represents the average extinction law with the total-to-selective extinction ratio r v = 3.16 ± 0.15. our observed extinction law supports an adjustment in parameters of the ccm r v = 3.1 curve, together with the near-ir (nir) power-law index α = 2.07 ± 0.03. the relative extinction values of the hubble space telescope (hst) and the james webb space telescope (jwst) nir bandpasses are predicted in 2.5% precision. as the observed reddening/extinction tracks are curved, the curvature correction needs to be considered when applying extinction correction. | the optical to mid-infrared extinction law based on the apogee, gaia dr2, pan-starrs1, sdss, apass, 2mass, and wise surveys |
we present a catalogue of 362 million stellar parameters, distances, and extinctions derived from gaia's early data release (edr3) cross-matched with the photometric catalogues of pan-starrs1, skymapper, 2mass, and allwise. the higher precision of the gaia edr3 data, combined with the broad wavelength coverage of the additional photometric surveys and the new stellar-density priors of the starhorse code, allows us to substantially improve the accuracy and precision over previous photo-astrometric stellar-parameter estimates. at magnitude g = 14 (17), our typical precisions amount to 3% (15%) in distance, 0.13 mag (0.15 mag) in v-band extinction, and 140 k (180 k) in effective temperature. our results are validated by comparisons with open clusters, as well as with asteroseismic and spectroscopic measurements, indicating systematic errors smaller than the nominal uncertainties for the vast majority of objects. we also provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps, and extensive stellar density maps that reveal detailed substructures in the milky way and beyond. the new density maps now probe a much greater volume, extending to regions beyond the galactic bar and to local group galaxies, with a larger total number density. we publish our results through an adql query interface (gaia.aip.de) as well as via tables containing approximations of the full posterior distributions. our multi-wavelength approach and the deep magnitude limit render our results useful also beyond the next gaia release, dr3. the catalog is available at the cds via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/658/a91 | photo-astrometric distances, extinctions, and astrophysical parameters for gaia edr3 stars brighter than g = 18.5 |
we present long baseline atacama large millimeter/submillimeter array (alma) observations of the 870 μm continuum emission from the nearest gas-rich protoplanetary disk, around tw hya, that trace millimeter-sized particles down to spatial scales as small as 1 au (20 mas). these data reveal a series of concentric ring-shaped substructures in the form of bright zones and narrow dark annuli (1-6 au) with modest contrasts (5%-30%). we associate these features with concentrations of solids that have had their inward radial drift slowed or stopped, presumably at local gas pressure maxima. no significant non-axisymmetric structures are detected. some of the observed features occur near temperatures that may be associated with the condensation fronts of major volatile species, but the relatively small brightness contrasts may also be a consequence of magnetized disk evolution (the so-called zonal flows). other features, particularly a narrow dark annulus located only 1 au from the star, could indicate interactions between the disk and young planets. these data signal that ordered substructures on ∼au scales can be common, fundamental factors in disk evolution and that high-resolution microwave imaging can help characterize them during the epoch of planet formation. | ringed substructure and a gap at 1 au in the nearest protoplanetary disk |
we study the properties of black holes and their host galaxies across cosmic time in the illustris simulation. illustris is a large-scale cosmological hydrodynamical simulation which resolves a (106.5 mpc)3 volume with more than 12 billion resolution elements and includes state-of-the-art physical models relevant for galaxy formation. we find that the black hole mass density for redshifts z = 0-5 and the black hole mass function at z = 0 predicted by illustris are in very good agreement with the most recent observational constraints. we show that the bolometric and hard x-ray luminosity functions of active galactic nuclei (agn) at z = 0 and 1 reproduce observational data very well over the full dynamic range probed. unless the bolometric corrections are largely underestimated, this requires radiative efficiencies to be on average low, ɛr ≲ 0.1, noting however that in our model radiative efficiencies are degenerate with black hole feedback efficiencies. cosmic downsizing of the agn population is in broad agreement with the findings from x-ray surveys, but we predict a larger number density of faint agn at high redshifts than currently inferred. we also study black hole-host galaxy scaling relations as a function of galaxy morphology, colour and specific star formation rate. we find that black holes and galaxies co-evolve at the massive end, but for low mass, blue and star-forming galaxies there is no tight relation with either their central black hole masses or the nuclear agn activity. | the illustris simulation: the evolving population of black holes across cosmic time |
with recent advances in gravitational-wave astronomy, the direct detection of gravitational waves from the merger of two stellar-mass compact objects has become a realistic prospect. evolutionary scenarios towards mergers of various double compact objects generally invoke so-called common-envelope evolution, which is poorly understood and leads to large uncertainties in the predicted merger rates. here we explore, as an alternative, the scenario of massive overcontact binary (mob) evolution, which involves two very massive stars in a very tight binary that remain fully mixed as a result of their tidally induced high spin. while many of these systems merge early on, we find many mobs that swap mass several times, but survive as a close binary until the stars collapse. the simplicity of the mob scenario allows us to use the efficient public stellar-evolution code mesa to explore it systematically by means of detailed numerical calculations. we find that, at low metallicity, mobs produce double-black-hole (bh+bh) systems that will merge within a hubble time with mass-ratios close to one, in two mass ranges, about 25...60 m⊙ and ≳130m⊙, with pair-instability supernovae (pisne) being produced at intermediate masses. our models are also able to reproduce counterparts of various stages in the mob scenario in the local universe, providing direct support for the scenario. we map the initial binary parameter space that produces bh+bh mergers, determine the expected chirp mass distribution, merger times, and expected kerr parameters, and predict event rates. we find typically one bh+bh merger event for ~1000 core-collapse supernovae for z ≲ z⊙/ 10 . the advanced ligo (aligo) detection rate is more uncertain and depends on the cosmic metallicity evolution. from deriving upper and lower limits from a local and a global approximation for the metallicity distribution of massive stars, we estimate aligo detection rates (at the aligo design limit) of ~19-550 yr-1 for bh-bh mergers below the pisn gap and of ~2.1-370 yr-1 above the pisn gap. even with conservative assumptions, we find that aligo will probably soon detect bh+bh mergers from the mob scenario. these could be the dominant source for aligo detections. | a new route towards merging massive black holes |
the mapping nearby galaxies at apache point observatory (manga) survey is currently acquiring integral-field spectroscopy for the largest sample of galaxies to date. by 2020, the manga survey—which is one of three core programs in the fourth-generation sloan digital sky survey (sdss-iv)—will have observed a statistically representative sample of 104 galaxies in the local universe (z ≲ 0.15). in addition to a robust data-reduction pipeline (drp), manga has developed a data-analysis pipeline (dap) that provides higher-level data products. to accompany the first public release of its code base and data products, we provide an overview of the manga dap, including its software design, workflow, measurement procedures and algorithms, performance, and output data model. in conjunction with our companion paper (belfiore et al.), we also assess the dap output provided for 4718 observations of 4648 unique galaxies in the recent sdss data release 15 (dr15). these analysis products focus on measurements that are close to the data and require minimal model-based assumptions. namely, we provide stellar kinematics (velocity and velocity dispersion), emission-line properties (kinematics, fluxes, and equivalent widths), and spectral indices (e.g., d4000 and the lick indices). we find that the dap provides robust measurements and errors for the vast majority (>99%) of analyzed spectra. we summarize assessments of the precision and accuracy of our measurements as a function of signal-to-noise. we also provide specific guidance to users regarding the limitations of the data. the manga dap software is publicly available and we encourage community involvement in its development. | the data analysis pipeline for the sdss-iv manga ifu galaxy survey: overview |
we perform radiation-hydrodynamics simulations of binary neutron-star mergers in numerical relativity on the japanese "k" supercomputer, taking into account neutrino cooling and heating by an updated leakage-plus-transfer scheme for the first time. neutron stars are modeled by three modern finite-temperature equations of state (eos) developed by hempel and his collaborators. we find that the properties of the dynamical ejecta of the merger such as total mass, average electron fraction, and thermal energy depend strongly on the eos. only for a soft eos (the so-called sfho), the ejecta mass exceeds 0.01 m⊙ . in this case, the distribution of the electron fraction of the ejecta becomes broad due to the shock heating during the merger. these properties are well-suited for the production of the solar-like r -process abundance. for the other stiff eos (dd2 and tm1), for which a long-lived massive neutron star is formed after the merger, the ejecta mass is smaller than 0.01 m⊙, although broad electron-fraction distributions are achieved by the positron capture and the neutrino heating. | dynamical mass ejection from binary neutron star mergers: radiation-hydrodynamics study in general relativity |
with the improving sensitivity of the global network of gravitational-wave detectors, we expect to observe hundreds of transient gravitational-wave events per year. the current methods used to estimate their source parameters employ optimally sensitive but computationally costly bayesian inference approaches, where typical analyses have taken between 6 h and 6 d. for binary neutron star and neutron star-black hole systems prompt counterpart electromagnetic signatures are expected on timescales between 1 s and 1 min. however, the current fastest method for alerting electromagnetic follow-up observers can provide estimates in of the order of 1 min on a limited range of key source parameters. here, we show that a conditional variational autoencoder pretrained on binary black hole signals can return bayesian posterior probability estimates. the training procedure need only be performed once for a given prior parameter space and the resulting trained machine can then generate samples describing the posterior distribution around six orders of magnitude faster than existing techniques. | bayesian parameter estimation using conditional variational autoencoders for gravitational-wave astronomy |
the sphere infrared exoplanet (shine) project is a 500-star survey performed with sphere on the very large telescope for the purpose of directly detecting new substellar companions and understanding their formation and early evolution. here we present an initial statistical analysis for a subsample of 150 stars spanning spectral types from b to m that are representative of the full shine sample. our goal is to constrain the frequency of substellar companions with masses between 1 and 75 mjup and semimajor axes between 5 and 300 au. for this purpose, we adopt detection limits as a function of angular separation from the survey data for all stars converted into mass and projected orbital separation using the bex-cond-hot evolutionary tracks and known distance to each system. based on the results obtained for each star and on the 13 detections in the sample, we use a markov chain monte carlo tool to compare our observations to two different types of models. the first is a parametric model based on observational constraints, and the second type are numerical models that combine advanced core accretion and gravitational instability planet population synthesis. using the parametric model, we show that the frequencies of systems with at least one substellar companion are 23.0−9.7+13.5, 5.8−2.8+4.7, and 12.6−7.1+12.9% for ba, fgk, and m stars, respectively. we also demonstrate that a planet-like formation pathway probably dominates the mass range from 1-75 mjup for companions around ba stars, while for m dwarfs, brown dwarf binaries dominate detections. in contrast, a combination of binary star-like and planet-like formation is required to best fit the observations for fgk stars. using our population model and restricting our sample to fgk stars, we derive a frequency of 5.7−2.8+3.8%, consistent with predictions from the parametric model. more generally, the frequency values that we derive are in excellent agreement with values obtained in previous studies. based on observations collected at the european southern observatory under eso programmes 095.c-0298, 095.c-0309, 096.c-241, 097.c-0865 and 198.c-0209. | the sphere infrared survey for exoplanets (shine). iii. the demographics of young giant exoplanets below 300 au with sphere |
our understanding of the properties and demographics of exoplanets critically relies on our ability to determine the fundamental properties of their host stars. the advent of gaia and large spectroscopic surveys has now made it possible, in principle, to infer the properties of individual stars, including most exoplanet hosts, to very high precision. however, we show that, in practice, such analyses are limited by uncertainties in both the fundamental scale and our models of stellar evolution, even for stars similar to the sun. for example, we show that current uncertainties on measured interferometric angular diameters and bolometric fluxes set a systematic uncertainty floor of ≈2.4% in temperature, ≈2.0% in luminosity, and ≈4.2% in radius. comparisons between widely available model grids suggest uncertainties of order ≈5% in mass and ≈20% in age for main-sequence and subgiant stars. while the radius uncertainties are roughly constant over this range of stars, the model-dependent uncertainties are a complex function of luminosity, temperature, and metallicity. we provide open-source software for approximating these uncertainties for individual targets and discuss strategies for reducing these uncertainties in the future. | a guide to realistic uncertainties on the fundamental properties of solar-type exoplanet host stars |
we introduce the thesan project, a suite of large volume ($l_\mathrm{box} = 95.5 \, \mathrm{cmpc}$) radiation-magnetohydrodynamic simulations that simultaneously model the large-scale statistical properties of the intergalactic medium during reionization and the resolved characteristics of the galaxies responsible for it. the flagship simulation has dark matter and baryonic mass resolutions of $3.1 \times 10^6\, {\rm m_\odot }$ and $5.8 \times 10^5\, {\rm m_\odot }$, respectively. the gravitational forces are softened on scales of 2.2 ckpc with the smallest cell sizes reaching 10 pc at z = 5.5, enabling predictions down to the atomic cooling limit. the simulations use an efficient radiation hydrodynamics solver (arepo-rt) that precisely captures the interaction between ionizing photons and gas, coupled to well-tested galaxy formation (illustristng) and dust models to accurately predict the properties of galaxies. through a complementary set of medium resolution simulations we investigate the changes to reionization introduced by different assumptions for ionizing escape fractions, varying dark matter models, and numerical convergence. the fiducial simulation and model variations are calibrated to produce realistic reionization histories that match the observed evolution of the global neutral hydrogen fraction and electron scattering optical depth to reionization. they also match a wealth of high-redshift observationally inferred data, including the stellar-to-halo-mass relation, galaxy stellar mass function, star formation rate density, and the mass-metallicity relation, despite the galaxy formation model being mainly calibrated at z = 0. we demonstrate that different reionization models give rise to varied bubble size distributions that imprint unique signatures on the 21 cm emission, especially on the slope of the power spectrum at large spatial scales, enabling current and upcoming 21 cm experiments to accurately characterize the sources that dominate the ionizing photon budget. | introducing the thesan project: radiation-magnetohydrodynamic simulations of the epoch of reionization |
we review the current knowledge about nuclear star clusters (nscs), and the spectacularly dense and massive assemblies of stars found at the centers of most galaxies. recent observational and theoretical works suggest that many nsc properties, including their masses, densities, and stellar populations, vary with the properties of their host galaxies. understanding the formation, growth, and ultimate fate of nscs, therefore, is crucial for a complete picture of galaxy evolution. throughout the review, we attempt to combine and distill the available evidence into a coherent picture of nsc evolution. combined, this evidence points to a clear transition mass in galaxies of ∼109m⊙ where the characteristics of nuclear star clusters change. we argue that at lower masses, nscs are formed primarily from globular clusters that inspiral into the center of the galaxy, while at higher masses, star formation within the nucleus forms the bulk of the nsc. we also discuss the co-existence of nscs and central black holes, and how their growth may be linked. the extreme densities of nscs and their interaction with massive black holes lead to a wide range of unique phenomena including tidal disruption and gravitational-wave events. finally, we review the evidence that many nscs end up in the halos of massive galaxies stripped of the stars that surrounded them, thus providing valuable tracers of the galaxies' accretion histories. | nuclear star clusters |
tools from scattering amplitudes and effective field theory have recently been repurposed to derive state-of-the-art results for the black hole binary inspiral in the post-minkowskian expansion. in the present letter, we extend this approach to include the tidal effects of mass and current quadrupoles on the conservative dynamics of nonspinning neutron star mergers. we compute the leading and, for the first time, next-to-leading order post-minkowskian finite size corrections to the conservative hamiltonian, together with their associated scattering amplitudes and scattering angles. our expressions are gauge invariant and, in the extreme mass ratio limit, consistent with the dynamics of a tidally deformed test body in a schwarzschild background. furthermore, they agree completely with existing results at leading post-minkowskian and second post-newtonian orders. | tidal effects in the post-minkowskian expansion |
we use chemistry ([alpha/fe] and [fe/h]), main sequence turnoff ages, and kinematics determined from h3 survey spectroscopy and gaia astrometry to identify the birth of the galactic disk. we separate in-situ and accreted stars on the basis of angular momenta and eccentricities. the sequence of high-alpha in-situ stars persists down to at least [fe/h]=-2.5 and shows unexpected non-monotonic behavior: with increasing metallicity the population first declines in [alpha/fe], then increases over the range -1.3<[fe/h]<-0.7, and then declines again at higher metallicities. the number of stars in the in-situ population rapidly increases above [fe/h]=-1. the average kinematics of these stars are hot and independent of metallicity at [fe/h]<-1 and then become increasingly cold and disk-like at higher metallicities. the ages of the in-situ, high-alpha stars are uniformly very old (13 gyr) at [fe/h]<-1.3, and span a wider range (8-12 gyr) at higher metallicities. interpreting the chemistry with a simple chemical evolution model suggests that the non-monotonic behavior is due to a significant increase in star formation efficiency, which began 13 gyr ago. these results support a picture in which the first 1 gyr of the galaxy was characterized by a "simmering phase" in which the star formation efficiency was low and the kinematics had substantial disorder with some net rotation. the disk then underwent a dramatic transformation to a "boiling phase", in which the star formation efficiency increased substantially, the kinematics became disk-like, and the number of stars formed increased tenfold. we interpret this transformation as the birth of the galactic disk at z~4. the physical origin of this transformation is unclear and does not seem to be reproduced in current galaxy formation models. | birth of the galactic disk revealed by the h3 survey |
this paper describes the identification, modelling, and removal of previously unexplained systematic effects in the polarization data of the planck high frequency instrument (hfi) on large angular scales, including new mapmaking and calibration procedures, new and more complete end-to-end simulations, and a set of robust internal consistency checks on the resulting maps. these maps, at 100, 143, 217, and 353 ghz, are early versions of those that will be released in final form later in 2016. the improvements allow us to determine the cosmic reionization optical depth τ using, for the first time, the low-multipole ee data from hfi, reducing significantly the central value and uncertainty, and hence the upper limit. two different likelihood procedures are used to constrain τ from two estimators of the cmb e- and b-mode angular power spectra at 100 and 143 ghz, after debiasing the spectra from a small remaining systematic contamination. these all give fully consistent results. a further consistency test is performed using cross-correlations derived from the low frequency instrument maps of the planck 2015 data release and the new hfi data. for this purpose, end-to-end analyses of systematic effects from the two instruments are used to demonstrate the near independence of their dominant systematic error residuals. the tightest result comes from the hfi-based τ posterior distribution using the maximum likelihood power spectrum estimator from ee data only, giving a value 0.055 ± 0.009. in a companion paper these results are discussed in the context of the best-fit planckλcdm cosmological model and recent models of reionization. | planck intermediate results. xlvi. reduction of large-scale systematic effects in hfi polarization maps and estimation of the reionization optical depth |
we present version 10 of the chianti package. in this release, we provide updated atomic models for several helium-like ions and for all the ions of the beryllium, carbon, and magnesium isoelectronic sequences that are abundant in astrophysical plasmas. we include rates from large-scale atomic structure and scattering calculations that are in many cases a significant improvement over the previous version, especially for the be-like sequence, which has useful line diagnostics to measure the electron density and temperature. we have also added new ions and updated several of them with new atomic rates and line identifications. also, we have added several improvements to the idl software, to speed up the calculations and to estimate the suppression of dielectronic recombination. | chianti—an atomic database for emission lines. xvi. version 10, further extensions |
data release 5 (dr5) of the radial velocity experiment (rave) is the fifth data release from a magnitude-limited (9< i< 12) survey of stars randomly selected in the southern hemisphere. the rave medium-resolution spectra (r∼ 7500) covering the ca-triplet region (8410-8795 å) span the complete time frame from the start of rave observations in 2003 to their completion in 2013. radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 255,922 stellar observations have parallaxes and proper motions from the tycho-gaia astrometric solution in gaia dr1. for our main dr5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the rave dr4 stellar pipeline, but calibrated using recent k2 campaign 1 seismic gravities and gaia benchmark stars, as well as results obtained from high-resolution studies. also included are temperatures from the infrared flux method, and we provide a catalog of red giant stars in the dereddened color {(j-{ks})}0 interval (0.50, 0.85) for which the gravities were calibrated based only on seismology. further data products for subsamples of the rave stars include individual abundances for mg, al, si, ca, ti, fe, and ni, and distances found using isochrones. each rave spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. the data can be accessed via the rave web site or the vizier database. | the radial velocity experiment (rave): fifth data release |
we confront observational data from gravitational wave event gw170817 with microscopic modeling of the cold neutron star equation of state. we develop and employ a bayesian statistical framework that enables us to implement constraints on the equation of state from laboratory measurements of nuclei and state-of-the-art chiral effective field theory methods. the energy density functionals constructed from the posterior probability distributions are then used to compute consistently the neutron star equation of state from the outer crust to the inner core, assuming a composition consisting of protons, neutrons, electrons, and muons. in contrast to previous studies, we find that the 95% credibility range of predicted neutron star tidal deformabilities (136 <λ <519 ) for a 1.4 solar-mass neutron star is already consistent with the upper bound deduced from observations of the gw170817 event. however, we find that lower bounds on the neutron star tidal deformability will very strongly constrain microscopic models of the dense matter equation of state. we also demonstrate a strong correlation between the neutron star tidal deformability and the pressure of beta-equilibrated matter at twice saturation density. | neutron star tidal deformabilities constrained by nuclear theory and experiment |
planets form and obtain their compositions in dust- and gas-rich disks around young stars, and the outcome of this process is intimately linked to the disk chemical properties. the distributions of molecules across disks regulate the elemental compositions of planets, including c/n/o/s ratios and metallicity (o/h and c/h), as well as access to water and prebiotically relevant organics. emission from molecules also encodes information on disk ionization levels, temperature structures, kinematics, and gas surface densities, which are all key ingredients of disk evolution and planet formation models. the molecules with alma at planet-forming scales (maps) alma large program was designed to expand our understanding of the chemistry of planet formation by exploring disk chemical structures down to 10 au scales. the maps program focuses on five disks-around im lup, gm aur, as 209, hd 163296, and mwc 480-in which dust substructures are detected and planet formation appears to be ongoing. we observed these disks in four spectral setups, which together cover ~50 lines from over 20 different species. this paper introduces the astrophysical journal supplement's maps special issue by presenting an overview of the program motivation, disk sample, observational details, and calibration strategy. we also highlight key results, including discoveries of links between dust, gas, and chemical substructures, large reservoirs of nitriles and other organics in the inner disk regions, and elevated c/o ratios across most disks. we discuss how this collection of results is reshaping our view of the chemistry of planet formation. | molecules with alma at planet-forming scales (maps). i. program overview and highlights |
the rapid neutron capture process (r process) is believed to be responsible for about half of the production of the elements heavier than iron and contributes to abundances of some lighter nuclides as well. a universal pattern of r-process element abundances is observed in some metal-poor stars of the galactic halo. this suggests that a well-regulated combination of astrophysical conditions and nuclear physics conspires to produce such a universal abundance pattern. the search for the astrophysical site for r-process nucleosynthesis has stimulated interdisciplinary research for more than six decades. there is currently much enthusiasm surrounding evidence for r-process nucleosynthesis in binary neutron star mergers in the multi-wavelength follow-up observations of kilonova/gravitational-wave grb170807a/gw170817. nevertheless, there remain questions as to the contribution over the history of the galaxy to the current solar-system r-process abundances from other sites such as neutrino-driven winds or magnetohydrodynamical ejection of material from core-collapse supernovae. in this review we highlight some current issues surrounding the nuclear physics input, astronomical observations, galactic chemical evolution, and theoretical simulations of r-process astrophysical environments with the goal of outlining a path toward resolving the remaining mysteries of the r process. | current status of r-process nucleosynthesis |
we discuss in detail the distributions of energy, radial pressure and tangential pressure inside the nucleon. in particular, this discussion is carried on in both the instant form and the front form of dynamics. moreover we show for the first time how these mechanical concepts can be defined when the average nucleon momentum does not vanish. we express the conditions of hydrostatic equilibrium and stability in terms of these two and three-dimensional energy and pressure distributions. we briefly discuss the phenomenological relevance of our findings with a simple yet realistic model. in the light of this exhaustive mechanical description of the nucleon, we also present several possible connections between hadronic physics and compact stars, like e.g. the study of the equation of state for matter under extreme conditions and stability constraints. | revisiting the mechanical properties of the nucleon |
we combine molecular gas masses inferred from co emission in 500 star-forming galaxies (sfgs) between z = 0 and 3, from the iram-coldgass, phibss1/2, and other surveys, with gas masses derived from herschel far-ir dust measurements in 512 galaxy stacks over the same stellar mass/redshift range. we constrain the scaling relations of molecular gas depletion timescale (t depl) and gas to stellar mass ratio (m mol gas/m* ) of sfgs near the star formation "main-sequence" with redshift, specific star-formation rate (ssfr), and stellar mass (m* ). the co- and dust-based scaling relations agree remarkably well. this suggests that the co → h2 mass conversion factor varies little within ±0.6 dex of the main sequence (ssfr(ms, z, m *)), and less than 0.3 dex throughout this redshift range. this study builds on and strengthens the results of earlier work. we find that t depl scales as (1 + z)-0.3 × (ssfr/ssfr(ms, z, m *))-0.5, with little dependence on m *. the resulting steep redshift dependence of m mol gas/m * ≈ (1 + z)3 mirrors that of the ssfr and probably reflects the gas supply rate. the decreasing gas fractions at high m* are driven by the flattening of the sfr-m * relation. throughout the probed redshift range a combination of an increasing gas fraction and a decreasing depletion timescale causes a larger ssfr at constant m *. as a result, galaxy integrated samples of the m mol gas-sfr rate relation exhibit a super-linear slope, which increases with the range of ssfr. with these new relations it is now possible to determine m mol gas with an accuracy of ±0.1 dex in relative terms, and ±0.2 dex including systematic uncertainties. based on observations with the plateau de bure millimetre interferometer, operated by the institute for radio astronomy in the millimetre range (iram), which is funded by a partnership of insu/cnrs (france), mpg (germany), and ign (spain). | combined co and dust scaling relations of depletion time and molecular gas fractions with cosmic time, specific star-formation rate, and stellar mass |
we present a cross-calibration of hipparcos and gaia edr3 intended to identify astrometrically accelerating stars and to fit orbits to stars with faint, massive companions. the resulting catalog, the edr3 edition of the hipparcos-gaia catalog of accelerations (hgca), provides three proper motions with calibrated uncertainties on the edr3 reference frame: the hipparcos proper motion, the gaia edr3 proper motion, and the long-term proper motion given by the difference in position between hipparcos and gaia edr3. our approach is similar to that for the gaia dr2 edition of the hgca but offers a factor of ∼3 improvement in precision thanks to the longer time baseline and improved data processing of gaia edr3. we again find that a 60/40 mixture of the two hipparcos reductions outperforms either reduction individually, and we find strong evidence for locally variable frame rotations between all pairs of proper motion measurements. the substantial global frame rotation seen in dr2 proper motions has been removed in edr3. we also correct for color- and magnitude-dependent frame rotations at a level of up to ∼50 μas yr-1 in gaia edr3. we calibrate the gaia edr3 uncertainties using a sample of radial velocity standard stars without binary companions; we find an error inflation factor (a ratio of total to formal uncertainty) of 1.37. this is substantially lower than the position-dependent factor of ∼1.7 found for gaia dr2 and reflects the improved data processing in edr3. while the catalog should be used with caution, its proper motion residuals provide a powerful tool to measure the masses and orbits of faint, massive companions to nearby stars. | the hipparcos-gaia catalog of accelerations: gaia edr3 edition |
we study relation between stellar mass and halo mass for high-mass halos using a sample of galaxy clusters with accurate measurements of stellar masses from optical and ifrared data and total masses from x-ray observations. we find that stellar mass of the brightest cluster galaxies (bcgs) scales as m *,bcg ∝ m 500αbcg with the best fit slope of α bcg ≈ 0.4 ± 0.1. we measure scatter of m *,bcg at a fixed m 500 of ≈0.2 dex. we show that stellar mass-halo mass relations from abundance matching or halo modelling reported in recent studies underestimate masses of bcgs by a factor of ∼2-4. we argue that this is because these studies used stellar mass functions (smf) based on photometry that severely underestimates the outer surface brightness profiles of massive galaxies. we show that m * -m relation derived using abundance matching with the recent smf calibration by bernardi et al. (2013) based on improved photometry is in a much better agreement with the relation we derive via direct calibration for observed clusters. the total stellar mass of galaxies correlates with total mass m 500 with the slope of ≈0.6 ± 0.1 and scatter of 0.1 dex. this indicates that efficiency with which baryons are converted into stars decreases with increasing cluster mass. the low scatter is due to large contribution of satellite galaxies: the stellar mass in satellite galaxies correlates with m 500 with scatter of ≈0.1 dex and best fit slope of αsat ≈ 0.8 ± 0.1. we show that for a fixed choice of the initial mass function (imf) total stellar fraction in clusters is only a factor of 3-5 lower than the peak stellar fraction reached in m ≈ 1012 m ⊙ halos. the difference is only a factor of ∼1.5-3 if the imf becomes progressively more bottom heavy with increasing mass in early type galaxies, as indicated by recent observational analyses. this means that the overall efficiency of star formation in massive halos is only moderately suppressed compared to l * galaxies and is considerably less suppressed than previously thought. the larger normalization and slope of the m *- m relation derived in this study shows that feedback and associated suppression of star formation in massive halos should be weaker than assumed in most of the current semi-analytic models and simulations. | stellar mass—halo mass relation and star formation efficiency in high-mass halos |
we present phantom, a fast, parallel, modular, and low-memory smoothed particle hydrodynamics and magnetohydrodynamics code developed over the last decade for astrophysical applications in three dimensions. the code has been developed with a focus on stellar, galactic, planetary, and high energy astrophysics, and has already been used widely for studies of accretion discs and turbulence, from the birth of planets to how black holes accrete. here we describe and test the core algorithms as well as modules for magnetohydrodynamics, self-gravity, sink particles, dust-gas mixtures, h2 chemistry, physical viscosity, external forces including numerous galactic potentials, lense-thirring precession, poynting-robertson drag, and stochastic turbulent driving. phantom is hereby made publicly available. | phantom: a smoothed particle hydrodynamics and magnetohydrodynamics code for astrophysics |
extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. we develop a novel effective-one-body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star-black-hole binaries. we demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star-black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency. | effects of neutron-star dynamic tides on gravitational waveforms within the effective-one-body approach |
the universe's biggest galaxies have both vast atmospheres and supermassive central black holes. this article reviews how those two components of a large galaxy couple and regulate the galaxy's star formation rate. models of interactions between a supermassive black hole and the large-scale atmosphere suggest that the energy released as cold gas clouds accrete onto the black hole suspends the atmosphere in a state that is marginally stable to formation of cold clouds. a growing body of observational evidence indicates that many massive galaxies, ranging from the huge central galaxies of galaxy clusters down to our own milky way, are close to that marginal state. the gas supply for star formation within a galaxy in such a marginal state is closely tied to the central velocity dispersion (σv) of its stars. we therefore explore the consequences of a model in which energy released during black-hole accretion shuts down star formation when σv exceeds a critical value determined by the galaxy's supernova heating rate. | baryon cycles in the biggest galaxies |
we have derived luminosity functions and set constraints on the uv luminosity and sfr density from z ~ 17 to z ~ 8, using the three most-studied jwst/nircam data sets, the smacs0723, glass parallel, and ceers fields. we first used our own selections on two independent reductions of these data sets using the latest calibrations. a total of 18 z ~ 8, 12 z ~ 10, 5 z ~ 13, and 1 z ~ 17 candidate galaxies are identified over these fields in our primary reductions, with a similar number of candidates in our secondary reductions. we then use these two reductions, applying a quantitative discriminator, to segregate the full set of z ≥ 8 candidates reported over these fields from the literature, into three different samples, 'robust', 'solid', and 'possible'. using all of these samples, we then derive uv lf and luminosity density results at z ≥ 8, finding substantial differences. for example, including the full set of 'solid' and 'possible' z ≥ 12 candidates from the literature, we find uv luminosity densities, which are ~7× and ~20× higher than relying on the 'robust' candidates alone. these results indicate the evolution of the uv lf and luminosity densities at z ≥ 8 is still extremely uncertain, emphasizing the need for spectroscopy and deeper nircam + optical imaging to obtain reliable results. nevertheless, even with the very conservative 'robust' approach to selections, both from our own and those of other studies, we find the luminosity density from luminous (muv < -19) galaxies to be ~2 × larger than is easily achievable using constant star formation efficiency models, similar to what other early jwst results have suggested. | uv luminosity density results at z > 8 from the first jwst/nircam fields: limitations of early data sets and the need for spectroscopy |
we present the first simulations of core-collapse supernovae in axial symmetry with feedback from fast neutrino flavor conversion (ffc). our schematic treatment of ffcs assumes instantaneous flavor equilibration under the constraint of lepton-number conservation individually for each flavor. systematically varying the spatial domain where ffcs are assumed to occur, we find that they facilitate sn explosions in low-mass (9 - 12 m⊙ ) progenitors that otherwise explode with longer time delays, whereas ffcs weaken the tendency to explode of higher-mass (around 20 m⊙) progenitors. | fast neutrino flavor conversions can help and hinder neutrino-driven explosions |
we present the full public release of all data from the illustris simulation project. illustris is a suite of large volume, cosmological hydrodynamical simulations run with the moving-mesh code arepo and including a comprehensive set of physical models critical for following the formation and evolution of galaxies across cosmic time. each simulates a volume of (106.5 mpc)3 and self-consistently evolves five different types of resolution elements from a starting redshift of z = 127 to the present day, z = 0. these components are: dark matter particles, gas cells, passive gas tracers, stars and stellar wind particles, and supermassive black holes. this data release includes the snapshots at all 136 available redshifts, halo and subhalo catalogs at each snapshot, and two distinct merger trees. six primary realizations of the illustris volume are released, including the flagship illustris-1 run. these include three resolution levels with the fiducial ;full; baryonic physics model, and a dark matter only analog for each. in addition, we provide four distinct, high time resolution, smaller volume ;subboxes;. the total data volume is ∼265 tb, including ∼800 full volume snapshots and ∼30,000 subbox snapshots. we describe the released data products as well as tools we have developed for their analysis. all data may be directly downloaded in its native hdf5 format. additionally, we release a comprehensive, web-based api which allows programmatic access to search and data processing tasks. in both cases we provide example scripts and a getting-started guide in several languages: currently, idl, python, and matlab. this paper addresses scientific issues relevant for the interpretation of the simulations, serves as a pointer to published and on-line documentation of the project, describes planned future additional data releases, and discusses technical aspects of the release. | the illustris simulation: public data release |
as low- and intermediate-mass stars reach the asymptotic giant branch (agb), they have developed into intriguing and complex objects that are major players in the cosmic gas/dust cycle. at this stage, their appearance and evolution are strongly affected by a range of dynamical processes. large-scale convective flows bring newly-formed chemical elements to the stellar surface and, together with pulsations, they trigger shock waves in the extended stellar atmosphere. there, massive outflows of gas and dust have their origin, which enrich the interstellar medium and, eventually, lead to a transformation of the cool luminous giants into white dwarfs. dust grains forming in the upper atmospheric layers play a critical role in the wind acceleration process, by scattering and absorbing stellar photons and transferring their outward-directed momentum to the surrounding gas through collisions. recent progress in high-angular-resolution instrumentation, from the visual to the radio regime, is leading to valuable new insights into the complex dynamical atmospheres of agb stars and their wind-forming regions. observations are revealing asymmetries and inhomogeneities in the photospheric and dust-forming layers which vary on time-scales of months, as well as more long-lived large-scale structures in the circumstellar envelopes. high-angular-resolution observations indicate at what distances from the stars dust condensation occurs, and they give information on the chemical composition and sizes of dust grains in the close vicinity of cool giants. these are essential constraints for building realistic models of wind acceleration and developing a predictive theory of mass loss for agb stars, which is a crucial ingredient of stellar and galactic chemical evolution models. at present, it is still not fully possible to model all these phenomena from first principles, and to predict the mass-loss rate based on fundamental stellar parameters only. however, much progress has been made in recent years, which is described in this review. we complement this by discussing how observations of emission from circumstellar molecules and dust can be used to estimate the characteristics of the mass loss along the agb, and in different environments. we also briefly touch upon the issue of binarity. | mass loss of stars on the asymptotic giant branch. mechanisms, models and measurements |
the planetary and lunar ephemerides called de440 and de441 have been generated by fitting numerically integrated orbits to ground-based and space-based observations. compared to the previous general-purpose ephemerides de430, seven years of new data have been added to compute de440 and de441, with improved dynamical models and data calibration. the orbit of jupiter has improved substantially by fitting to the juno radio range and very long baseline array (vlba) data of the juno spacecraft. the orbit of saturn has been improved by radio range and vlba data of the cassini spacecraft, with improved estimation of the spacecraft orbit. the orbit of pluto has been improved from use of stellar occultation data reduced against the gaia star catalog. the ephemerides de440 and de441 are fit to the same data set, but de441 assumes no damping between the lunar liquid core and the solid mantle, which avoids a divergence when integrated backward in time. therefore, de441 is less accurate than de440 for the current century, but covers a much longer duration of years -13,200 to +17,191, compared to de440 covering years 1550-2650. | the jpl planetary and lunar ephemerides de440 and de441 |
we present emerge, an empirical model for the formation of galaxies, describing the evolution of individual galaxies in large volumes from z ∼ 10 to the present day. we assign a star formation rate to each dark matter halo based on its growth rate, which specifies how much baryonic material becomes available, and the instantaneous baryon conversion efficiency, which determines how efficiently this material is converted to stars, thereby capturing the baryonic physics. satellites are quenched following the delayed-then-rapid model, and they are tidally disrupted once their subhalo has lost a significant fraction of its mass. the model is constrained with observed data extending out to high redshift. the empirical relations are very flexible, and the model complexity is increased only if required by the data, assessed by several model selection statistics. we find that for the same final halo mass galaxies can have very different star formation histories. galaxies that are quenched at z = 0 typically have a higher peak star formation rate compared to their star-forming counterparts. emerge predicts stellar-to-halo mass ratios for individual galaxies and introduces scatter self-consistently. we find that at fixed halo mass, passive galaxies have a higher stellar mass on average. the intracluster mass in massive haloes can be up to eight times larger than the mass of the central galaxy. clustering for star-forming and quenched galaxies is in good agreement with observational constraints, indicating a realistic assignment of galaxies to haloes. | emerge - an empirical model for the formation of galaxies since z ∼ 10 |
observations of neutron stars, whether in binaries or in isolation, provide information about the internal structure of the most extreme material objects in the universe. in this work, we combine information from recent observations to place joint constraints on the properties of neutron star matter. we use (i) lower limits on the maximum mass of neutron stars obtained through radio observations of heavy pulsars, (ii) constraints on tidal properties inferred through the gravitational waves neutron star binaries emit as they coalesce, and (iii) information about neutron stars' masses and radii obtained through x-ray emission from surface hot spots. in order to combine information from such distinct messengers while avoiding the kind of modeling systematics intrinsic to parametric inference schemes, we employ a nonparametric representation of the neutron-star equation of state based on gaussian processes conditioned on nuclear theory models. we find that existing astronomical observations imply r1.4=12.3 2-1.47+1.09 km for the radius of a 1.4 m⊙ neutron star and p (2 ρnuc)=3. 8-2.9+2.7 ×1 034 dyn /cm2 for the pressure at twice nuclear saturation density at the 90% credible level. the upper bounds are driven by the gravitational wave observations, while x-ray and heavy pulsar observations drive the lower bounds. additionally, we compute expected constraints from potential future astronomical observations and find that they can jointly determine r1.4 to o (1 ) km and p (2 ρnuc) to 80% relative uncertainty in the next five years. | nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations |
there is compelling evidence that the most massive galaxies in the universe stopped forming stars due to the time-integrated feedback from their central super-massive black holes (smbhs). however, the exact quenching mechanism is not yet understood, because local massive galaxies were quenched billions of years ago. we present jwst/nirspec integral-field spectroscopy observations of gs-10578, a massive, quiescent galaxy at redshift z=3.064. from the spectrum we infer that the galaxy has a stellar mass of $m_*=1.6\pm0.2 \times 10^{11}$ msun and a dynamical mass $m_{\rm dyn}=2.0\pm0.5 \times 10^{11}$ msun. half of its stellar mass formed at z=3.7-4.6, and the system is now quiescent, with the current star-formation rate sfr<9 msun/yr. we detect ionised- and neutral-gas outflows traced by [oiii] emission and nai absorption. outflow velocities reach $v_{\rm out}\approx$1,000 km/s, comparable to the galaxy escape velocity and too high to be explained by star formation alone. gs-10578 hosts an active galactic nucleus (agn), evidence that these outflows are due to smbh feedback. the outflow rates are 0.14-2.9 and 30-300 msun/yr for the ionised and neutral phases, respectively. the neutral outflow rate is ten times higher than the sfr, hence this is direct evidence for ejective smbh feedback, with mass-loading capable of interrupting star formation by rapidly removing its fuel. stellar kinematics show ordered rotation, with spin parameter $\lambda_{re}=0.62\pm0.07$, meaning gs-10578 is rotation supported. this study shows direct evidence for ejective agn feedback in a massive, recently quenched galaxy, thus clarifying how smbhs quench their hosts. quenching can occur without destroying the stellar disc. | a fast-rotator post-starburst galaxy quenched by supermassive black-hole feedback at z=3 |
gaia stellar measurements are currently revolutionizing our knowledge of the evolutionary history of the milky way. 3d maps of the interstellar dust provide complementary information and are a tool for a wide range of uses. we built 3d maps of the dust in the local arm and surrounding regions. to do so, gaia dr2 photometric data were combined with 2mass measurements to derive extinction toward stars that possess accurate photometry and relative uncertainties on dr2 parallaxes smaller than 20%. we applied a new hierarchical inversion algorithm to the individual extinctions that is adapted to large datasets and to an inhomogeneous target distribution. each step associates regularized bayesian inversions in all radial directions and a subsequent inversion in 3d of all their results. each inverted distribution serves as a prior for the subsequent step, and the spatial resolution is progressively increased. we present the resulting 3d distribution of the dust in a 6 × 6 × 0.8 kpc3 volume around the sun. its main features are found to be elongated along different directions that vary from below to above the mid-plane. the outer part of carina-sagittarius, mainly located above the mid-plane, the local arm/cygnus rift around and above the mid-plane, and the fragmented perseus arm are oriented close to the direction of circular motion. the spur of more than 2 kpc length (nicknamed the split) that extends between the local arm and carina-sagittarius, the compact near side of carina-sagittarius, and the cygnus rift below the plane are oriented along l ~40 to 55°. dust density images in vertical planes reveal a wavy pattern in some regions and show that the solar neighborhood within ~500 pc remains atypical by its extent above and below the plane. we show several comparisons with the locations of molecular clouds, hii regions, o stars, and masers. the link between the dust concentration and these tracers is markedly different from one region to the other. the extinction cube (fits) is only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/625/a135 | gaia-2mass 3d maps of galactic interstellar dust within 3 kpc |
a comprehensive and detailed account of the physics of gravitational waves and their role in astrophysics and cosmology. the part on astrophysical sources of gravitational waves includes chapters on gws from supernovae, neutron stars (neutron star normal modes, cfs instability, r-modes), black-hole perturbation theory (regge-wheeler and zerilli equations, teukoslky equation for rotating bhs, quasi-normal modes) coalescing compact binaries (effective one-body formalism, numerical relativity), discovery of gravitational waves at the advanced ligo interferometers (discoveries of gw150914, gw151226, tests of general relativity, astrophysical implications), supermassive black holes (supermassive black-hole binaries, emri, relevance for lisa and pulsar timing arrays). the part on gravitational waves and cosmology include discussions of frw cosmology, cosmological perturbation theory (helicity decomposition, scalar and tensor perturbations, bardeen variables, power spectra, transfer functions for scalar and tensor modes), the effects of gws on the cosmic microwave background (isw effect, cmb polarization, e and b modes), inflation (amplification of vacuum fluctuations, quantum fields in curved space, generation of scalar and tensor perturbations, mukhanov-sasaki equation,reheating, preheating), stochastic backgrounds of cosmological origin (phase transitions, cosmic strings, alternatives to inflation, bounds on primordial gws) and search of stochastic backgrounds with pulsar timing arrays (pta). | gravitational waves: volume 2: astrophysics and cosmology |
measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems1,2. access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based3-5 and high-resolution ground-based6-8 facilities. here we report the medium-resolution (r ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm covering several absorption features for the saturn-mass exoplanet wasp-39b (ref. 9), obtained with the near infrared spectrograph (nirspec) g395h grating of jwst. our observations achieve 1.46 times photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. we detect significant absorption from co2 (28.5σ) and h2o (21.5σ), and identify so2 as the source of absorption at 4.1 μm (4.8σ). best-fit atmospheric models range between 3 and 10 times solar metallicity, with sub-solar to solar c/o ratios. these results, including the detection of so2, underscore the importance of characterizing the chemistry in exoplanet atmospheres and showcase nirspec g395h as an excellent mode for time-series observations over this critical wavelength range10. | early release science of the exoplanet wasp-39b with jwst nirspec g395h |
we analyse the ligo-virgo data, including the recently released gwtc-2dataset, to test a hypothesis that the data contains more than one population of black holes. we perform a maximum likelihood analysis including a population of astrophysical black holes with a truncated power-law mass function whose merger rate follows from star formation rate, and a population of primordial black holes for which we consider log-normal and critical collapse mass functions. we find that primordial black holes alone are strongly disfavoured by the data, while the best fit is obtained for the template combining astrophysical and primordial merger rates. alternatively, the data may hint towards two different astrophysical black hole populations. we also update the constraints on primordial black hole abundance from ligo-virgo observations finding that in the 2-400 mass range they must comprise less than 0.2% of dark matter. | two populations of ligo-virgo black holes |
we review all the models proposed for the progenitor systems of type ia supernovae and discuss the strengths and weaknesses of each scenario when confronted with observations. we show that all scenarios encounter at least a few serious difficulties, if taken to represent a comprehensive model for the progenitors of all type ia supernovae (sne ia). consequently, we tentatively conclude that there is probably more than one channel leading sne ia. while the single-degenerate scenario (in which a single white dwarf accretes mass from a normal stellar companion) has been studied in some detail, the other scenarios will need a similar level of scrutiny before any firm conclusions can be drawn. | on the progenitors of type ia supernovae |
we present the public data release of halo and galaxy catalogues extracted from the eagle suite of cosmological hydrodynamical simulations of galaxy formation. these simulations were performed with an enhanced version of the gadget code that includes a modified hydrodynamics solver, time-step limiter and subgrid treatments of baryonic physics, such as stellar mass loss, element-by-element radiative cooling, star formation and feedback from star formation and black hole accretion. the simulation suite includes runs performed in volumes ranging from 25 to 100 comoving megaparsecs per side, with numerical resolution chosen to marginally resolve the jeans mass of the gas at the star formation threshold. the free parameters of the subgrid models for feedback are calibrated to the redshift z = 0 galaxy stellar mass function, galaxy sizes and black hole mass-stellar mass relation. the simulations have been shown to match a wide range of observations for present-day and higher-redshift galaxies. the raw particle data have been used to link galaxies across redshifts by creating merger trees. the indexing of the tree produces a simple way to connect a galaxy at one redshift to its progenitors at higher redshift and to identify its descendants at lower redshift. in this paper we present a relational database which we are making available for general use. a large number of properties of haloes and galaxies and their merger trees are stored in the database, including stellar masses, star formation rates, metallicities, photometric measurements and mock gri images. complex queries can be created to explore the evolution of more than 105 galaxies, examples of which are provided in the appendix. the relatively good and broad agreement of the simulations with a wide range of observational datasets makes the database an ideal resource for the analysis of model galaxies through time, and for connecting and interpreting observational datasets. | the eagle simulations of galaxy formation: public release of halo and galaxy catalogues |
the galaxy and mass assembly (gama) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. covering an area of ∼286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the aaomega spectrograph on the anglo-australian telescope. in addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. we also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. finally, we present the second public release of gama data. in this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component sérsic fits, stellar masses, hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). the data base serving these data is available at http://www.gama-survey.org/. | galaxy and mass assembly (gama): end of survey report and data release 2 |
the ligo scientific collaboration and the virgo collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. all eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. the data around the time of each of these events have been made publicly available through the gravitational-wave open science center. the entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. there is considerable interest among the broad scientific community in understanding the data and methods used in the analyses. in this paper, we provide an overview of the detector noise properties and the data analysis techniques used to detect gravitational-wave signals and infer the source properties. we describe some of the checks that are performed to validate the analyses and results from the observations of gravitational-wave events. we also address concerns that have been raised about various properties of ligo-virgo detector noise and the correctness of our analyses as applied to the resulting data. | a guide to ligo-virgo detector noise and extraction of transient gravitational-wave signals |
despite their long history and astrophysical importance, some of the key properties of neutron stars are still uncertain. the extreme conditions encountered in their interiors, involving matter of uncertain composition at extreme density and isospin asymmetry, uniquely determine the stars' macroscopic properties within general relativity. astrophysical constraints on those macroscopic properties, such as neutron-star masses and radii, have long been used to understand the microscopic properties of the matter that forms them. in this article we discuss another astrophysically observable macroscopic property of neutron stars that can be used to study their interiors: their tidal deformation. neutron stars, much like any other extended object with structure, are tidally deformed when under the influence of an external tidal field. in the context of coalescences of neutron stars observed through their gravitational-wave emission, this deformation, quantified through a parameter termed the tidal deformability, can be measured. we discuss the role of the tidal deformability in observations of coalescing neutron stars with gravitational waves and how it can be used to probe the internal structure of nature's most compact matter objects. perhaps inevitably, a large portion of the discussion will be dictated by gw170817, the most informative confirmed detection of a binary neutron-star coalescence with gravitational waves as of the time of writing. | neutron-star tidal deformability and equation-of-state constraints |
we present a catalog of 4195 optically confirmed sunyaev-zel’dovich (sz) selected galaxy clusters detected with signal-to-noise ratio >4 in 13,211 deg2 of sky surveyed by the atacama cosmology telescope (act). cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 ghz maps constructed from act observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. the clusters span the redshift range 0.04 < z < 1.91 (median z = 0.52). the catalog contains 222 z > 1 clusters, and a total of 868 systems are new discoveries. assuming an sz signal versus mass-scaling relation calibrated from x-ray observations, the sample has a 90% completeness mass limit of m 500c > 3.8 × 1014 m ⊙, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio >5 in maps filtered at an angular scale of 2.′4. the survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the sz signal mass-scaling relation, such as the dark energy survey (4566 deg2), the hyper suprime-cam subaru strategic program (469 deg2), and the kilo degree survey (825 deg2). we highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. the cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 gyr. | the atacama cosmology telescope: a catalog of >4000 sunyaev-zel’dovich galaxy clusters |
we review the present status of the experimental and theoretical developments in the field of strangeness in nuclei and neutron stars. we start by discussing the k ¯ n interaction, that is governed by the presence of the λ(1405) . we continue by showing the two-pole nature of the λ(1405) , and the production mechanisms in photon-, pion-, kaon-induced reactions as well as proton-proton collisions, while discussing the formation of k ¯ nn bound states. we then move to the theoretical and experimental analysis of the properties of kaons and antikaons in dense nuclear matter, paying a special attention to kaonic atoms and the analysis of strangeness creation and propagation in nuclear collisions. next, we examine the ϕ meson and the advances in photoproduction, proton-induced and pion-induced reactions, so as to understand its properties in dense matter. finally, we address the dynamics of hyperons with nucleons and nuclear matter, and the connection to the phases of dense matter with strangeness in the interior of neutron stars. | strangeness in nuclei and neutron stars |
the power-law slope of the rest-uv continuum ($f_{\lambda}\propto\lambda^{\beta}$) is a key metric of early star forming galaxies, providing one of our only windows into the stellar populations and physical conditions of $z>10$ galaxies. expanding upon previous studies with limited sample sizes, we leverage deep imaging from jades to investigate the uv slopes of 179 $z>9$ galaxies with apparent magnitudes of $m_{\rm f200w}=26-31$, which display a median uv slope of $\beta=-2.4$. we compare to a statistical sample of $z=5-9$ galaxies, finding a shift toward bluer rest-uv colors at all $\rm~m_{uv}$. the most uv-luminous $z>9$ galaxies are significantly bluer than their lower-redshift counterparts, representing a dearth of moderately-red galaxies in the first $500~$myr. at yet earlier times, the $z>11$ galaxy population exhibits very blue uv slopes, implying very low attenuation from dust. we identify a robust sample of 44 galaxies with $\beta<-2.8$, which have seds requiring models of density-bounded hii regions and median ionizing photon escape fractions of $0.51$ to reproduce. their rest-optical colors imply that this sample has weaker emission lines (median $m_{\rm f356w}-m_{\rm f444w}=0.19$ mag) than typical galaxies (median $m_{\rm f356w}-m_{\rm f444w}=0.39$ mag), consistent with the inferred escape fractions. this sample has relatively low stellar masses (median $\log(m/m_{\odot})=7.5$), and specific star-formation rates (median$=79\rm/gyr$) nearly twice that of our full sample (median$=44\rm/gyr$), suggesting they are more common among systems experiencing a recent upturn in star formation. we demonstrate that the shutoff of star formation provides an alternative solution for modelling of extremely blue uv colors, making distinct predictions for the rest-optical emission of these galaxies. future spectroscopy will be required to distinguish between these physical pictures. | the uv continuum slopes of early star-forming galaxies in jades |
astrophysical black holes are expected to be described by the kerr metric. this is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies einstein's equations and does not have pathologies outside of the event horizon. we present new constraints on potential deviations from the kerr prediction based on 2017 eht observations of sagittarius a* (sgr a*). we calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both kerr and non-kerr simulations. we use the exquisite prior constraints on the mass-to-distance ratio for sgr a* to show that the observed image size is within $\sim$ 10$\%$ of the kerr predictions. we use these bounds to constrain metrics that are parametrically different from kerr as well as the charges of several known spacetimes. to consider alternatives to the presence of an event horizon we explore the possibility that sgr a* is a compact object with a surface that either absorbs and thermally re-emits incident radiation or partially reflects it. using the observed image size and the broadband spectrum of sgr a*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. we compare our results to the broader landscape of gravitational tests. together with the bounds found for stellar mass black holes and the m87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the kerr metric, independent of their mass. | first sagittarius a* event horizon telescope results. vi: testing the black hole metric |
the central engine that powers gamma-ray bursts (grbs), the most powerful explosions in the universe, is still not identified. besides hyper-accreting black holes, rapidly spinning and highly magnetized neutron stars, known as millisecond magnetars, have been suggested to power both long and short grbs. the presence of a magnetar engine following compact star mergers is of particular interest as it would provide essential constraints on the poorly understood equation of state for neutron stars. indirect indications of a magnetar engine in these merger sources have been observed in the form of plateau features present in the x-ray afterglow light curves of some short grbs. additionally, some x-ray transients lacking gamma-ray bursts (grb-less) have been identified as potential magnetar candidates originating from compact star mergers. nevertheless, smoking gun evidence is still lacking for a magnetar engine in short grbs, and the associated theoretical challenges have been addressed. here we present a comprehensive analysis of the broad-band prompt emission data of a peculiar, very bright grb 230307a. despite its apparently long duration, the prompt emission and host galaxy properties point toward a compact star merger origin, being consistent with its association with a kilonova. more intriguingly, an extended x-ray emission component emerges as the $\gamma$-ray emission dies out, signifying the emergence of a magnetar central engine. we also identify an achromatic temporal break in the high-energy band during the prompt emission phase, which was never observed in previous bursts and reveals a narrow jet with half opening angle of approximately $3.4^\circ$. | magnetar emergence in a peculiar gamma-ray burst from a compact star merger |
we study the population of supermassive black holes (smbhs) and their effects on massive central galaxies in the illustristng cosmological hydrodynamical simulations of galaxy formation. the employed model for smbh growth and feedback assumes a two-mode scenario in which the feedback from active galactic nuclei occurs through a kinetic, comparatively efficient mode at low accretion rates relative to the eddington limit, and in the form of a thermal, less efficient mode at high accretion rates. we show that the quenching of massive central galaxies happens coincidently with kinetic-mode feedback, consistent with the notion that active supermassive black holes cause the low specific star formation rates observed in massive galaxies. however, major galaxy mergers are not responsible for initiating most of the quenching events in our model. up to black hole masses of about 10^{8.5} m_{⊙}, the dominant growth channel for smbhs is in the thermal mode. higher mass black holes stay mainly in the kinetic mode and gas accretion is self-regulated via their feedback, which causes their eddington ratios to drop, with smbh mergers becoming the main channel for residual mass growth. as a consequence, the quasar luminosity function is dominated by rapidly accreting, moderately massive black holes in the thermal mode. we show that the associated growth history of smbhs produces a low-redshift quasar luminosity function and a redshift zero black hole mass - stellar bulge mass relation is in good agreement with observations, whereas the simulation tends to overpredict the high-redshift quasar luminosity function. | supermassive black holes and their feedback effects in the illustristng simulation |
stellar standard candles provide the absolute calibration for measuring the universe's local expansion rate, h0, which differs by ~8% from the value inferred using the cosmic microwave background assuming the concordance cosmological model, lambdacdm. this hubble tension indicates a need for important revisions of fundamental physics. however, the accuracy of the h0 measurement based on classical cepheids has been challenged by a measurement based on the tip of the red giant branch (trgb) method. a resolution of the cepheids vs. trgb dispute is needed to demonstrate well understood systematics and to corroborate the need for new physics. here, we present an unprecedented 1.39% absolute calibration of the trgb distance scale based on small-amplitude red giant stars (osargs). our results improve by 20% upon previous calibrations and are limited by the accuracy of the distance to the large magellanic cloud. this precision gain is enabled by the realization that virtually all stars at the trgb are variable - a fact not previously exploited for trgb calibration. using observations and extensive simulations, we demonstrate that osargs yield intrinsically precise and accurate trgb measurements thanks to the shape of their luminosity function. inputting our calibration to the carnegie chicago hubble program's h0 analysis yields a value of h0 = 71.8 +/- 1.5 km/s/mpc, in < 1 sigma agreement with the cepheids-based h0 value and in 2.8 sigma tension with the early-universe value. | reconciling astronomical distance scales with variable red giant stars |
the evolution of star-forming regions and their thermal balance are strongly influenced by their chemical composition, that, in turn, is determined by the physico-chemical processes that govern the transition between the gas phase and the solid state, specifically icy dust grains (e.g., particles adsorption and desorption). gas-grain and grain-gas transitions as well as formation and sublimation of interstellar ices are thus essential elements of understanding astrophysical observations of cold environments (e.g., pre-stellar cores) where unexpected amounts of a large variety of chemical species have been observed in the gas phase. adsorbed atoms and molecules also undergo chemical reactions which are not efficient in the gas phase. therefore, the parameterization of the physical properties of atoms and molecules interacting with dust grain particles is clearly a key aspect to interpret astronomical observations and to build realistic and predictive astrochemical models. in this consensus evaluation, we focus on parameters controlling the thermal desorption of ices and how these determine pathways towards molecular complexity and define the location of snowlines, which ultimately influence the planet formation process. we review different crucial aspects of desorption parameters both from a theoretical and experimental point of view. we critically assess the desorption parameters commonly used in the astrochemical community for astrophysical relevant species and provide tables with recommended values. in addition, we show that a non-trivial determination of the pre-exponential factor nu using the transition state theory can affect the binding energy value. finally, we conclude this work by discussing the limitations of theoretical and experimental approaches currently used to determine the desorption properties with suggestions for future improvements. | thermal desorption of interstellar ices: a review on the controlling parameters and their implications from snowlines to chemical complexity |
the extreme astrophysical processes and conditions that characterize the early universe are expected to result in young galaxies that are dynamically different from those observed today1-5. this is because the strong effects associated with galaxy mergers and supernova explosions would lead to most young star-forming galaxies being dynamically hot, chaotic and strongly unstable1,2. here we report the presence of a dynamically cold, but highly star-forming, rotating disk in a galaxy at redshift6z = 4.2, when the universe was just 1.4 billion years old. galaxy spt-s j041839-4751.9 is strongly gravitationally lensed by a foreground galaxy at z = 0.263, and it is a typical dusty starburst, with global star-forming7 and dust properties8 that are in agreement with current numerical simulations9 and observations10. interferometric imaging at a spatial resolution of about 60 parsecs reveals a ratio of rotational to random motions of 9.7 ± 0.4, which is at least four times larger than that expected from any galaxy evolution model at this epoch1-5 but similar to the ratios of spiral galaxies in the local universe11. we derive a rotation curve with the typical shape of nearby massive spiral galaxies, which demonstrates that at least some young galaxies are dynamically akin to those observed in the local universe, and only weakly affected by extreme physical processes. | a dynamically cold disk galaxy in the early universe |
neutron stars provide a window into the properties of dense nuclear matter. several recent observational and theoretical developments provide powerful constraints on their structure and internal composition. among these are the first observed binary neutron star merger, gw170817, whose gravitational radiation was accompanied by electromagnetic radiation from a short γ-ray burst and an optical afterglow believed to be due to the radioactive decay of newly minted heavy r-process nuclei. these observations give important constraints on the radii of typical neutron stars and on the upper limit to the neutron star maximum mass and complement recent pulsar observations that established a lower limit. pulse-profile observations by the neutron star interior composition explorer (nicer) x-ray telescope provide an independent, consistent measure of the neutron star radius. theoretical many-body studies of neutron matter reinforce these estimates of neutron star radii. studies using parameterized dense matter equations of state (eoss) reveal several eos-independent relations connecting global neutron star properties. | neutron stars and the nuclear matter equation of state |
we present the kepler object of interest (koi) catalog of transiting exoplanets based on searching 4 yr of kepler time series photometry (data release 25, q1-q17). the catalog contains 8054 kois, of which 4034 are planet candidates with periods between 0.25 and 632 days. of these candidates, 219 are new, including two in multiplanet systems (koi-82.06 and koi-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. this catalog was created using a tool called the robovetter, which automatically vets the dr25 threshold crossing events (tces). the robovetter also vetted simulated data sets and measured how well it was able to separate tces caused by noise from those caused by low signal-to-noise transits. we discuss the robovetter and the metrics it uses to sort tces. for orbital periods less than 100 days the robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. for the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. however, for low signal-to-noise candidates between 200 and 500 days around fgk-dwarf stars, the robovetter is 76.7% complete and the catalog is 50.5% reliable. the koi catalog, the transit fits, and all of the simulated data used to characterize this catalog are available at the nasa exoplanet archive. | planetary candidates observed by kepler. viii. a fully automated catalog with measured completeness and reliability based on data release 25 |
we exhibit an initial-value formulation of the worldline quantum field theory (wqft) approach to the classical two-body problem in general relativity. we show that the schwinger-keldysh (in-in) formalism leads to purely retarded propagators in the evaluation of observables in the wqft. integration technology for retarded master integrals is introduced at third post-minkowskian (3pm) order. as an application we compute the complete radiation-reacted impulse and radiated four momentum for the scattering of two non-spinning neutron stars including tidal effects at 3pm order, as well as the leading (2pm) far-field gravitational waveform. | all things retarded: radiation-reaction in worldline quantum field theory |
we present optical and ultraviolet spectra of the first electromagnetic counterpart to a gravitational-wave (gw) source, the binary neutron star merger gw170817. spectra were obtained nightly between 1.5 and 9.5 days post-merger, using the southern astrophysical research and magellan telescopes; the uv spectrum was obtained with the hubble space telescope at 5.5 days. our data reveal a rapidly fading blue component (t≈ 5500 k at 1.5 days) that quickly reddens; spectra later than ≳ 4.5 days peak beyond the optical regime. the spectra are mostly featureless, although we identify a possible weak emission line at ∼7900 å at t≲ 4.5 days. the colors, rapid evolution, and featureless spectrum are consistent with a “blue” kilonova from polar ejecta comprised mainly of light r-process nuclei with atomic mass number a≲ 140. this indicates a sightline within {θ }{obs}≲ 45^\circ of the orbital axis. comparison to models suggests ∼0.03 m ⊙ of blue ejecta, with a velocity of ∼ 0.3c. the required lanthanide fraction is ∼ {10}-4, but this drops to < {10}-5 in the outermost ejecta. the large velocities point to a dynamical origin, rather than a disk wind, for this blue component, suggesting that both binary constituents are neutron stars (as opposed to a binary consisting of a neutron star and a black hole). for dynamical ejecta, the high mass favors a small neutron star radius of ≲ 12 km. this mass also supports the idea that neutron star mergers are a major contributor to r-process nucleosynthesis. | the electromagnetic counterpart of the binary neutron star merger ligo/virgo gw170817. iii. optical and uv spectra of a blue kilonova from fast polar ejecta |
advanced ligo-virgo have reported a short gravitational-wave signal (gw190521) interpreted as a quasicircular merger of black holes, one at least populating the pair-instability supernova gap, that formed a remnant black hole of mf∼142 m⊙ at a luminosity distance of dl∼5.3 gpc . with barely visible pre-merger emission, however, gw190521 merits further investigation of the pre-merger dynamics and even of the very nature of the colliding objects. we show that gw190521 is consistent with numerically simulated signals from head-on collisions of two (equal mass and spin) horizonless vector boson stars (aka proca stars), forming a final black hole with mf=23 1-17+13 m⊙, located at a distance of dl=57 1-181+348 mpc . this provides the first demonstration of close degeneracy between these two theoretical models, for a real gravitational-wave event. the favored mass for the ultralight vector boson constituent of the proca stars is μv=8.7 2-0.82+0.73×10-13 ev . confirmation of the proca star interpretation, which we find statistically slightly preferred, would provide the first evidence for a long sought dark matter particle. | gw190521 as a merger of proca stars: a potential new vector boson of 8.7 ×10-13 ev |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.