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classification of stars, by comparing their optical spectra to a few dozen spectral standards, has been a workhorse of observational astronomy for more than a century. here, we extend this technique by compiling a library of optical spectra of 404 touchstone stars observed with keck/hires by the california planet search. the spectra have high resolution (r ≈ 60,000), high signal-to-noise ratio (s/n ≈ 150/pixel), and are registered onto a common wavelength scale. the library stars have properties derived from interferometry, asteroseismology, lte spectral synthesis, and spectrophotometry. to address a lack of well-characterized late-k dwarfs in the literature, we measure stellar radii and temperatures for 23 nearby k dwarfs, using modeling of the spectral energy distribution and gaia parallaxes. this library represents a uniform data set spanning the spectral types ∼m5-f1 (t eff ≈ 3000-7000 k, r ⋆ ≈ 0.1-16 r ⊙). we also present “empirical specmatch” (specmatch-emp), a tool for parameterizing unknown spectra by comparing them against our spectral library. for fgkm stars, specmatch-emp achieves accuracies of 100 k in effective temperature (t eff), 15% in stellar radius (r ⋆), and 0.09 dex in metallicity ([fe/h]). because the code relies on empirical spectra it performs particularly well for stars ∼k4 and later, which are challenging to model with existing spectral synthesizers, reaching accuracies of 70 k in t eff, 10% in r ⋆, and 0.12 dex in [fe/h]. we also validate the performance of specmatch-emp, finding it to be robust at lower spectral resolution and s/n, enabling the characterization of faint late-type stars. both the library and stellar characterization code are publicly available. | precision stellar characterization of fgkm stars using an empirical spectral library |
since the discovery of neutron stars with masses around 2 {{m}⊙ } the composition of matter in the central part of these massive stars has been intensively discussed. within this paper we will (re)investigate the question of the appearance of hyperons. to that end we will perform an extensive parameter study within relativistic mean field models. we will show that it is possible to obtain high mass neutron stars with (i) a substantial amount of hyperons, (ii) radii of 12-13 km for the canonical mass of 1.4 {{m}⊙ }, and (iii) a spinodal instability at the onset of hyperons. the results depend strongly on the interaction in the hyperon-hyperon channels, on which only very little information is available from terrestrial experiments up to now. | hyperons in neutron star matter within relativistic mean-field models |
while it is incontrovertible that the inner galaxy contains a bar, its structure near the galactic plane has remained uncertain, where extinction from intervening dust is greatest. we investigate here the galactic bar outside the bulge, the long bar, using red clump giant (rcg) stars from united kingdom infrared deep sky survey, two micron all sky survey, vista variables in the via lactea and galactic legacy infrared midplane survey extraordinaire. we match and combine these surveys to investigate a wide area in latitude and longitude, |b| ≤ 9° and |l| ≤ 40°. we find (i) the bar extends to l ∼ 25° at |b| ∼ 5° from the galactic plane, and to l ∼ 30° at lower latitudes; (ii) the long bar has an angle to the line-of-sight in the range (28°-33°), consistent with studies of the bulge at |l| < 10°; (iii) the scale height of rcg stars smoothly transitions from the bulge to the thinner long bar; (iv) there is evidence for two scale heights in the long bar; we find a ∼180 pc thin bar component reminiscent of the old thin disc near the sun, and a ∼45 pc superthin bar components which exist predominantly towards the bar end; (v) constructing parametric models for the red clump magnitude distributions, we find a bar half-length of 5.0 ± 0.2 kpc for the two-component bar, and 4.6 ± 0.3 kpc for the thin bar component alone. we conclude that the milky way contains a central box/peanut bulge which is the vertical extension of a longer, flatter bar, similar as seen in both external galaxies and n-body models. | the structure of the milky way's bar outside the bulge |
we derive bayesian distances for all stars in the radial velocity sample of gaia dr2, and use the statistical method of schönrich, binney & asplund to validate the distances and test the gaia parallaxes. in contrast to other methods, which rely on special sources, our method directly tests the distances to all stars in our sample. we find clear evidence for a near-linear trend of distance bias f with distance s, proving a parallax offset δp. on average, we find {δ _p}= -0.054 mas (parallaxes in gaia dr2 need to be increased) when accounting for the parallax uncertainty underestimate in the gaia set (compared to {δ _p}= -0.048 mas on the raw parallax errors), with negligible formal error and a systematic uncertainty of about 0.006 mas. the value is in concordance with results from asteroseismic measurements, but differs from the much lower bias found on quasar samples. we further use our method to compile a comprehensive set of quality cuts in colour, apparent magnitude, and astrometric parameters. lastly, we find that for this sample δp appears to strongly depend on σp (when including the additional 0.043 mas) with a statistical confidence far in excess of 10σ and a proportionality factor close to 1, though the dependence varies somewhat with σp. correcting for the σp dependence also resolves otherwise unexplained correlations of the offset with the number of observation periods {n_vis} and ecliptic latitude. every study using gaia dr2 parallaxes/distances should investigate the sensitivity of its results on the parallax biases described here and - for fainter samples - in the dr2 astrometry paper. | distances and parallax bias in gaia dr2 |
in this paper, we investigate how massive central galaxies cease their star formation by comparing theoretical predictions from cosmological simulations: eagle, illustris, and illustristng with observations of the local universe from the sloan digital sky survey (sdss). our machine learning (ml) classification reveals supermassive black hole mass (mbh) as the most predictive parameter in determining whether a galaxy is star forming or quenched at redshift z = 0 in all three simulations. this predicted consequence of active galactic nucleus (agn) quenching is reflected in the observations, where it is true for a range of indirect estimates of mbh via proxies as well as its dynamical measurements. our partial correlation analysis shows that other galactic parameters lose their strong association with quiescence, once their correlations with mbh are accounted for. in simulations, we demonstrate that it is the integrated power output of the agn, rather than its instantaneous activity, which causes galaxies to quench. finally, we analyse the change in molecular gas content of galaxies from star-forming to passive populations. we find that both gas fractions (fgas) and star formation efficiencies (sfes) decrease upon transition to quiescence in the observations but sfe is more predictive than fgas in the ml passive/star-forming classification. these trends in the sdss are most closely recovered in illustristng and are in direct contrast with the predictions made by illustris. we conclude that a viable agn feedback prescription can be achieved by a combination of preventative feedback and turbulence injection which together quench star formation in central galaxies. | on the quenching of star formation in observed and simulated central galaxies: evidence for the role of integrated agn feedback |
the solid content of circumstellar disks is inherited from the interstellar medium: dust particles of at most a micrometer in size. protoplanetary disks are the environment where these dust grains need to grow at least 13 orders of magnitude in size. our understanding of this growth process is far from complete, with different physics seemingly posing obstacles to this growth at various stages. yet, the ubiquity of planets in our galaxy suggests that planet formation is a robust mechanism. this chapter focuses on the earliest stages of planet formation, the growth of small dust grains towards the gravitationally bound "planetesimals", the building blocks of planets. we will introduce some of the key physics involved in the growth processes and discuss how they are expected to shape the global behavior of the solid content of disks. we will consider possible pathways towards the formation of larger bodies and conclude by reviewing some of the recent observational advances in the field. | dust evolution and the formation of planetesimals |
we study the formation of planetesimals in protoplanetary disks from the gravitational collapse of solid over-densities generated via the streaming instability. to carry out these studies, we implement and test a particle-mesh self-gravity module for the athena code that enables the simulation of aerodynamically coupled systems of gas and collisionless self-gravitating solid particles. upon employment of our algorithm to planetesimal formation simulations, we find that (when a direct comparison is possible) the athena simulations yield predicted planetesimal properties that agree well with those found in prior work using different numerical techniques. in particular, the gravitational collapse of streaming-initiated clumps leads to an initial planetesimal mass function that is well-represented by a power law, {dn}/{{dm}}p\propto {m}p-p, with p≃ 1.6+/- 0.1, which equates to a differential size distribution of {dn}/{{dr}}p\propto {r}p-q, with q≃ 2.8+/- 0.1. we find no significant trends with resolution from a convergence study of up to 5123 grid zones and {n}{{par}}≈ 1.5× {10}8 particles. likewise, the power-law slope appears indifferent to changes in the relative strength of self-gravity and tidal shear, and to the time when (for reasons of numerical economy) self-gravity is turned on, though the strength of these claims is limited by small number statistics. for a typically assumed radial distribution of minimum mass solar nebula solids (assumed here to have dimensionless stopping time τ =0.3), our results support the hypothesis that bodies on the scale of large asteroids or kuiper belt objects could have formed as the high-mass tail of a primordial planetesimal population. | the mass and size distribution of planetesimals formed by the streaming instability. i. the role of self-gravity |
we present a new set of models for intermediate-mass asymptotic giant branch (agb) stars (4.0, 5.0, and 6.0 m⊙) at different metallicities (-2.15 ≤ [fe/h] ≤ +0.15). this set integrates the existing models for low-mass agb stars (1.3 ≤ m/m⊙ ≤ 3.0) already included in the fruity database. we describe the physical and chemical evolution of the computed models from the main sequence up to the end of the agb phase. due to less efficient third dredge up episodes, models with large core masses show modest surface enhancements. this effect is due to the fact that the interpulse phases are short and, therefore, thermal pulses (tps) are weak. moreover, the high temperature at the base of the convective envelope prevents it from deeply penetrating the underlying radiative layers. depending on the initial stellar mass, the heavy element nucleosynthesis is dominated by different neutron sources. in particular, the s-process distributions of the more massive models are dominated by the 22ne(α,n)25mg reaction, which is efficiently activated during tps. at low metallicities, our models undergo hot bottom burning and hot third dredge up. we compare our theoretical final core masses to available white dwarf observations. moreover, we quantify the influence intermediate-mass models have on the carbon star luminosity function. finally, we present the upgrade of the fruity web interface, which now also includes the physical quantities of the tp-agb phase for all of the models included in the database (ph-fruity). | evolution, nucleosynthesis, and yields of agb stars at different metallicities. iii. intermediate-mass models, revised low-mass models, and the ph-fruity interface |
we present a new model of the nebular emission from star-forming galaxies in a wide range of chemical compositions, appropriate to interpret observations of galaxies at all cosmic epochs. the model relies on the combination of state-of-the-art stellar population synthesis and photoionization codes to describe the ensemble of h ii regions and the diffuse gas ionized by young stars in a galaxy. a main feature of this model is the self-consistent yet versatile treatment of element abundances and depletion on to dust grains, which allows one to relate the observed nebular emission from a galaxy to both gas-phase and dust-phase metal enrichment. we show that this model can account for the rest-frame ultraviolet and optical emission-line properties of galaxies at different redshifts and find that ultraviolet emission lines are more sensitive than optical ones to parameters such as c/o abundance ratio, hydrogen gas density, dust-to-metal mass ratio and upper cut-off of the stellar initial mass function. we also find that, for gas-phase metallicities around solar to slightly subsolar, widely used formulae to constrain oxygen ionic fractions and the c/o ratio from ultraviolet and optical emission-line luminosities are reasonable faithful. however, the recipes break down at non-solar metallicities, making them inappropriate to study chemically young galaxies. in such cases, a fully self-consistent model of the kind presented in this paper is required to interpret the observed nebular emission. | modelling the nebular emission from primeval to present-day star-forming galaxies |
the low-energy electronic recoil spectrum in xenon1t provides an intriguing hint for potential new physics. at the same time, observations of horizontal branch stars favor the existence of a small amount of extra cooling compared to the one expected from the standard model particle content. in this note, we argue that a hidden photon with a mass of ~ 2.5 kev and a kinetic mixing of ~ 10-15 allows for a good fit to both of these excesses. in this scenario, the signal detected in xenon1t is due to the absorption of hidden photon dark matter particles, whereas the anomalous cooling of horizontal branch stars arises from resonant production of hidden photons in the stellar interior. | hidden photon dark matter in the light of xenon1t and stellar cooling |
this book is for anyone who owns, or is thinking of owning, a vixen star book ten telescope mount or its predecessor. a revolution in amateur astronomy has occurred in the past decade with the wide availability of high tech, computer-driven, go-to telescopes. vixen optics is leading the way by offering the star book ten system, with its unique star map graphics software. | the vixen star book user guide: how to use the star book ten and the original star book |
double detonations in double white dwarf (wd) binaries undergoing unstable mass transfer have emerged in recent years as one of the most promising type ia supernova (sn ia) progenitor scenarios. one potential outcome of this “dynamically driven double-degenerate double-detonation” (d6) scenario is that the companion wd survives the explosion and is flung away with a velocity equal to its >1000 km s-1 pre-sn orbital velocity. we perform a search for these hypervelocity runaway wds using gaia's second data release. in this paper, we discuss seven candidates followed up with ground-based instruments. three sources are likely to be some of the fastest known stars in the milky way, with total galactocentric velocities between 1000 and 3000 km s-1, and are consistent with having previously been companion wds in pre-sn ia systems. however, although the radial velocity of one of the stars is >1000 km s-1, the radial velocities of the other two stars are puzzlingly consistent with 0. the combined five-parameter astrometric solutions from gaia and radial velocities from follow-up spectra yield tentative 6d confirmation of the d6 scenario. the past position of one of these stars places it within a faint, old sn remnant, further strengthening the interpretation of these candidates as hypervelocity runaways from binary systems that underwent sne ia. | three hypervelocity white dwarfs in gaia dr2: evidence for dynamically driven double-degenerate double-detonation type ia supernovae |
the gravity instrument on the eso vlti pioneers the field of high-precision near-infrared interferometry by providing astrometry at the 10-100 μas level. measurements at this high precision crucially depend on the control of systematic effects. we investigate how aberrations introduced by small optical imperfections along the path from the telescope to the detector affect the astrometry. we develop an analytical model that describes the effect of these aberrations on the measurement of complex visibilities. our formalism accounts for pupil-plane and focal-plane aberrations, as well as for the interplay between static and turbulent aberrations, and it successfully reproduces calibration measurements of a binary star. the galactic center observations with gravity in 2017 and 2018, when both sgr a* and the star s2 were targeted in a single fiber pointing, are affected by these aberrations at a level lower than 0.5 mas. removal of these effects brings the measurement in harmony with the dual-beam observations of 2019 and 2020, which are not affected by these aberrations. this also resolves the small systematic discrepancies between the derived distance r0 to the galactic center that were reported previously. gravity is developed in a collaboration by the max planck institute for extraterrestrial physics, lesia of observatoire de paris/université psl/cnrs/sorbonne université/université de paris and ipag of université grenoble alpes/cnrs, the max planck institute for astronomy, the university of cologne, the centra - centro de astrofisica e gravitação, and the european southern observatory. | improved gravity astrometric accuracy from modeling optical aberrations |
a comprehensive study of the atmospheric neutrino flux in the energy region from sub-gev up to several tev using the super-kamiokande (sk) water cherenkov detector is presented in this paper. the energy and azimuthal spectra, and variation over time, of the atmospheric νe+ν¯ e and νμ+ν¯μ fluxes are measured. the energy spectra are obtained using an iterative unfolding method by combining various event topologies with differing energy responses. the azimuthal spectra depending on energy and zenith angle, and their modulation by geomagnetic effects, are also studied. a predicted east-west asymmetry is observed in both the νe and νμ samples at 8.0 σ and 6.0 σ significance, respectively, and an indication that the asymmetry dipole angle changes depending on the zenith angle was seen at the 2.2 σ level. the measured energy and azimuthal spectra are consistent with the current flux models within the estimated systematic uncertainties. a study of the long-term correlation between the atmospheric neutrino flux and the solar magnetic activity cycle is performed, and a weak preference for a correlation was seen at the 1.1 σ level, using sk-i-sk-iv data spanning a 20-year period. for several particularly strong solar activity periods, corresponding to forbush decrease events, no theoretical prediction is available but a deviation below the typical neutrino event rate is seen at the 2.4 σ level. the seasonal modulation of the neutrino flux is also examined, but the change in flux at the sk site is predicted to be negligible, and, as expected, no evidence for a seasonal correlation is seen. | measurements of the atmospheric neutrino flux by super-kamiokande: energy spectra, geomagnetic effects, and solar modulation |
we introduce the astrid simulation, a large-scale cosmological hydrodynamic simulation in a $250 \, h^{-1}\mathrm{mpc}$ box with 2 × 55003 particles. astrid contains a large number of high redshift galaxies, which can be compared to future survey data, and resolves galaxies in haloes more massive than $2\times 10^9 \, \mathrm{m}_{\odot }$. astrid has been run from z = 99 to 3. as a particular focus is modelling the high redshift universe, it contains models for inhomogeneous hydrogen and helium reionization, baryon relative velocities and massive neutrinos, as well as supernova and agn feedback. the black hole model includes mergers driven by dynamical friction rather than repositioning. we briefly summarize the implemented models, and the technical choices we took when developing the simulation code. we validate the model, showing good agreement with observed ultraviolet luminosity functions, galaxy stellar mass functions and specific star formation rates (sfrs). we show that the redshift at which a given galaxy underwent hydrogen reionization has a large effect on the halo gas fraction. finally, at z = 6, haloes with $m \sim 2\times 10^9 \, \mathrm{m}_{\odot }$ which have been reionized have an sfr 1.5 times greater than those which have not yet been reionized. | the astrid simulation: galaxy formation and reionization |
we present early-phase panchromatic photometric and spectroscopic coverage spanning the far-ultraviolet to near-infrared regime of the nearest hydrogen-rich core-collapse supernova (sn) in the last 25 yr, sn 2023ixf. we observe early "flash" features in the optical spectra due to confined dense circumstellar material (csm). we observe high-ionization absorption lines (fe ii, mg ii) in the ultraviolet spectra from very early on. we also observe a multipeaked emission profile of hα in the spectrum beginning at ~16 days, which indicates ongoing interaction of the sn ejecta with a preexisting shell-shaped csm having an inner radius of ~75 au and an outer radius of ~140 au. the shell-shaped csm is likely a result of enhanced mass loss ~35-65 yr before the explosion assuming a standard red supergiant wind. the uv spectra are dominated by multiple highly ionized narrow absorption and broad emission features from elements such as c, n, o, si, fe, and ni. based on early light-curve models of type ii sne, we infer that the nearby dense csm confined to 7 ± 3 × 1014 cm (~45 au) is a result of enhanced mass loss (10-3.0±0.5 m ⊙ yr-1) two decades before the explosion. | far-ultraviolet to near-infrared observations of sn 2023ixf: a high-energy explosion engulfed in complex circumstellar material |
the galactic bulge can uniquely be studied from large samples of individual stars and is therefore of prime importance for understanding the stellar population structure of bulges in general. here the observational evidence on the kinematics, chemical composition, and ages of bulge stellar populations based on photometric and spectroscopic data is reviewed. the bulk of bulge stars are old and span a metallicity range of -1.5≲[fe/h]≲+0.5. stellar populations and chemical properties suggest a star-formation timescale below ∼2 gyr. the overall bulge is barred and follows cylindrical rotation, and the more metal-rich stars trace a box/peanut (b/p) structure. dyna-mical models demonstrate the different spatial and orbital distributions of metal-rich and metal-poor stars. we discuss current bulge-formation scenarios based on dynamical, chemical, chemodynamical, and cosmological models. despite impressive progress, we do not yet have a successful fully self-consistent chemodynamical bulge model in the cosmological framework, and we will also need a more extensive chrono-chemical-kinematic 3d map of stars to better constrain such models. | chemodynamical history of the galactic bulge |
we present the physical extent of [c ii] 158 μm line-emitting gas from 46 star-forming galaxies at z = 4-6 from the alma large program to investigate c ii at early times (alpine). using exponential profile fits, we measure the effective radius of the [c ii] line (${r}_{{\rm{e}},[{\rm{c}}{\rm\small{ii}}]}$) for individual galaxies and compare them with the rest-frame ultraviolet (uv) continuum (${r}_{{\rm{e}},\mathrm{uv}}$) from hubble space telescope images. the effective radius ${r}_{{\rm{e}},[{\rm{c}}{\rm\small{ii}}]}$ exceeds ${r}_{{\rm{e}},\mathrm{uv}}$ by factors of ∼2-3, and the ratio of ${r}_{{\rm{e}},[{\rm{c}}{\rm\small{ii}}]}/{r}_{{\rm{e}},\mathrm{uv}}$ increases as a function of mstar. we do not find strong evidence that the [c ii] line, rest-frame uv, and far-infrared (fir) continuum are always displaced over ≃1 kpc scale from each other. we identify 30% of isolated alpine sources as having an extended [c ii] component over 10 kpc scales detected at 4.1σ-10.9σ beyond the size of rest-frame uv and fir continuum. one object has tentative rotating features up to ∼10 kpc, where the 3d model fit shows the rotating [c ii]-gas disk spread over 4 times larger than the rest-frame uv-emitting region. galaxies with the extended [c ii] line structure have high star formation rate, high stellar mass (mstar), low lyα equivalent width, and more blueshifted (redshifted) rest-frame uv metal absorption (lyα line), as compared to galaxies without such extended [c ii] structures. although we cannot rule out the possibility that a selection bias toward luminous objects may be responsible for such trends, the star-formation-driven outflow also explains all these trends. deeper observations are essential to test whether the extended [c ii] line structures are ubiquitous to high-z star-forming galaxies. | the alpine-alma [c ii] survey: size of individual star-forming galaxies at z = 4-6 and their extended halo structure |
there are a number of observational hints from astrophysics which point to the existence of stellar energy losses beyond the ones accounted for by neutrino emission. these excessive energy losses may be explained by the existence of a new sub-kev mass pseudoscalar nambu-goldstone boson with tiny couplings to photons, electrons, and nucleons. an attractive possibility is to identify this particle with the axion—the hypothetical pseudo nambu-goldstone boson predicted by the peccei-quinn solution to the strong cp problem. we explore this possibility in terms of a dfsz-type axion and of a ksvz-type axion/majoron, respectively. both models allow a good global fit to the data, prefering an axion mass around 10 mev. we show that future axion experiments—the fifth force experiment ariadne and the helioscope iaxo—can attack the preferred mass range from the lower and higher end, respectively. an axion in this mass range can also be the main constituent of dark matter. | stellar recipes for axion hunters |
we report the discovery of 854 ultra-diffuse galaxies (udgs) in the coma cluster using deep r band images, with partial b, i, and hα band coverage, obtained with the subaru telescope. many of them (332) are milky way (mw) sized with very large effective radii of {r}{e}\gt 1.5 {kpc}. this study was motivated by the recent discovery of 47 udgs by dokkum et al.; our discovery suggests \gt 1000 udgs after accounting for the smaller subaru field (4.1 {{degree}}2; about one-half of dragonfly). the new subaru udgs show a distribution concentrated around the cluster center, strongly suggesting that the great majority are (likely longtime) cluster members. they are a passively evolving population, lying along the red sequence in the color-magnitude diagram with no signature of hα emission. star formation was, therefore, quenched in the past. they have exponential light profiles, effective radii {r}{e}∼ 800\{pc}-5 {kpc}, effective surface brightnesses {μ }{e}({\text{}}r) = 25-28 mag arcsec-2, and stellar masses ∼ 1× {10}7{\text{}}{m}⊙ -5× {10}8{\text{}}{m}⊙ . there is also a population of nucleated udgs. some mw-sized udgs appear closer to the cluster center than previously reported; their survival in the strong tidal field, despite their large sizes, possibly indicates a large dark matter fraction protecting the diffuse stellar component. the indicated baryon fraction ≲ 1% is less than the cosmic average, and thus the gas must have been removed (from the possibly massive dark halo). the udg population is elevated in the coma cluster compared to the field, indicating that the gas removal mechanism is related primarily to the cluster environment. | approximately a thousand ultra-diffuse galaxies in the coma cluster |
we investigate the stellar populations for a sample of 24 quiescent galaxies at 1.5 < z < 2.5 using deep rest-frame optical spectra obtained with keck mosfire. by fitting templates simultaneously to the spectroscopic and photometric data and exploring a variety of star formation histories, we obtain robust measurements of median stellar ages and residual levels of star formation. after subtracting the stellar templates, the stacked spectrum reveals the hα and [n ii] emission lines, providing an upper limit on the ongoing star formation rate of 0.9 ± 0.1 {m}⊙yr-1. by combining the mosfire data with our sample of keck lris spectra at lower redshift, we analyze the quiescent population at 1 < z < 2.5 in a consistent manner. we find a tight relation (with a scatter of 0.13 dex) between the stellar age and the rest-frame u - v and v - j colors, which can be used to estimate the age of quiescent galaxies, given their colors. applying this age-color relation to large photometric samples, we are able to model the number density evolution for quiescent galaxies of various ages. we find evidence for two distinct quenching paths: a fast quenching that produces compact post-starburst systems and a slow quenching of larger galaxies. fast quenching accounts for about a fifth of the growth of the red sequence at z ∼ 1.4 and half at z ∼ 2.2. we conclude that fast quenching is triggered by dramatic events, such as gas-rich mergers, while slow quenching is likely caused by a different physical mechanism. | mosfire spectroscopy of quiescent galaxies at 1.5 < z < 2.5. ii. star formation histories and galaxy quenching |
understanding the formation and evolution of the stellar-mass binary black holes discovered by ligo and virgo is a challenge that spans many areas of astrophysics, from stellar evolution, dynamics and accretion disks, to possible exotic early universe processes. over the final years of their lives, stellar-mass binaries radiate gravitational waves that are first observable by space-based detectors (such as lisa) and then ground-based instruments (such as ligo, virgo and the next generation observatories cosmic explorer and the einstein telescope). using state-of-the-art waveform models and parameter-estimation pipelines for both ground- and space-based observations, we show that (the expected handful of) these multiband observations will allow at least percent-level measurements of all 17 parameters that describe the binary, the possible identification of a likely host galaxy, and the forewarning of the merger days in advance allowing telescopes at multiple wavelengths to search for any electromagnetic signature associated to it. multiband sources will therefore be a gold mine for astrophysics, but we also show that they could be less useful as laboratories for fundamental tests of general relativity than has been previously suggested. | the last three years: multiband gravitational-wave observations of stellar-mass binary black holes |
in the present article, we have obtained a new solution for the charged compact star model through the gravitational decoupling (gd) by using a complete geometric deformation (cgd) approach (ovalle, phys lett b 788:213, 2019). in this approach, the initial decoupled system is separated into two subsystems namely einstein-maxwell's system and quasi-einstein system. we solve einstein-maxwell's system by taking well known tolman-kuchowicz spacetime geometry in the context of the perfect fluid matter distribution. on the other hand, the second system introduce the anisotropy inside the matter distribution which is solved by taking an eos in θ components. the boundary conditions have been derived to determine the constants parameter. to support the mathematical and physical analysis of the present gd solution, we have plotted all the graphs for the compact objects psr j1614-2230, 4u1608-52 and cen x-3 corresponding to the constant α =0.001 , 0.0012 and 0.0014, respectively. moreover, we also studied the equilibrium and stability of the solution. the present study shows that the gd technique is a very significant tool to generalize the solution in a more complex form or one matter distribution to another matter distribution. | extended gravitational decoupling (gd) solution for charged compact star model |
we present the results of the gould’s belt distances survey of young star-forming regions toward the orion molecular cloud complex. we detected 36 young stellar objects (ysos) with the very large baseline array, 27 of which have been observed in at least three epochs over the course of two years. at least half of these ysos belong to multiple systems. we obtained parallax and proper motions toward these stars to study the structure and kinematics of the complex. we measured a distance of 388 ± 5 pc toward the orion nebula cluster, 428 ± 10 pc toward the southern portion l1641, 388 ± 10 pc toward ngc 2068, and roughly ∼420 pc toward ngc 2024. finally, we observed a strong degree of plasma radio scattering toward λ ori. | the gould’s belt distances survey (gobelins) ii. distances and structure toward the orion molecular clouds |
pebbles of millimeter sizes are abundant in protoplanetary discs around young stars. chondrules inside primitive meteorites - formed by melting of dust aggregate pebbles or in impacts between planetesimals - have similar sizes. the role of pebble accretion for terrestrial planet formation is nevertheless unclear. here we present a model where inwards-drifting pebbles feed the growth of terrestrial planets. the masses and orbits of venus, earth, theia (which later collided with the earth to form the moon) and mars are all consistent with pebble accretion onto protoplanets that formed around mars' orbit and migrated to their final positions while growing. the isotopic compositions of earth and mars are matched qualitatively by accretion of two generations of pebbles, carrying distinct isotopic signatures. finally, we show that the water and carbon budget of earth can be delivered by pebbles from the early generation before the gas envelope became hot enough to vaporise volatiles. | a pebble accretion model for the formation of the terrestrial planets in the solar system |
gaussian states have played an important role in the physics of continuous-variable quantum systems. they are appealing for the experimental ease with which they can be produced, and for their compact and elegant mathematical description. nevertheless, many proposed quantum technologies require us to go beyond the realm of gaussian states and introduce non-gaussian elements. in this tutorial, we provide a roadmap for the physics of non-gaussian quantum states. we introduce the phase-space representations as a framework to describe the different properties of quantum states in continuous-variable systems. we then use this framework in various ways to explore the structure of the state space. we explain how non-gaussian states can be characterized not only through the negative values of their wigner function, but also via other properties such as quantum non-gaussianity and the related stellar rank. for multimode systems, we are naturally confronted with the question of how non-gaussian properties behave with respect to quantum correlations. to answer this question, we first show how non-gaussian states can be created by performing measurements on a subset of modes in a gaussian state. then, we highlight that these measured modes must be correlated via specific quantum correlations to the remainder of the system to create quantum non-gaussian or wigner-negative states. on the other hand, non-gaussian operations are also shown to enhance or even create quantum correlations. finally, we demonstrate that wigner negativity is a requirement to violate bell inequalities and to achieve a quantum computational advantage. at the end of the tutorial, we also provide an overview of several experimental realizations of non-gaussian quantum states in quantum optics and beyond. | non-gaussian quantum states and where to find them |
experiments on bilayer graphene unveiled a fascinating realization of stacking disorder where triangular domains with well-defined bernal stacking are delimited by a hexagonal network of strain solitons. here we show by means of numerical simulations that this is a consequence of a structural transformation of the moiré pattern inherent to twisted bilayer graphene taking place at twist angles θ below a crossover angle θ\star=1.2\circ . the transformation is governed by the interplay between the interlayer van der waals interaction and the in-plane strain field, and is revealed by a change in the functional form of the twist energy density. this transformation unveils an electronic regime characteristic of vanishing twist angles in which the charge density converges, though not uniformly, to that of ideal bilayer graphene with bernal stacking. on the other hand, the stacking domain boundaries form a distinct charge density pattern that provides the stm signature of the hexagonal solitonic network. | structural and electronic transformation in low-angle twisted bilayer graphene |
multi-messenger observations of neutron star (ns) mergers have the potential to revolutionize nuclear astrophysics. they will improve our understanding of nucleosynthesis, provide insights about the equation of state (eos) of strongly interacting matter at high densities, and enable tests of the theory of gravity and of dark matter. here, we focus on the eos, where both gravitational waves (gws) from neutron-star mergers and x-ray observations from space-based detectors such as nicer will provide more stringent constraints on the structure of neutron stars. furthermore, recent advances in nuclear theory have enabled reliable calculations of the eos at low densities using effective field theory based hamiltonians and advanced techniques to solve the quantum many-body problem. in this paper, we address how the first observation of gws from gw170817 can be combined with modern calculations of the eos to extract useful insights about the eos of matter encountered inside neutron stars. we analyze the impact of various uncertainties, the role of phase transitions in the ns core, and discuss how future observations will improve our understanding of dense matter. | confronting gravitational-wave observations with modern nuclear physics constraints |
recent observations of neutron stars with gravitational waves and x-ray timing provide unprecedented access to the equation of state (eos) of cold dense matter at densities difficult to realize in terrestrial experiments. at the same time, predictions for the eos equipped with reliable uncertainty estimates from chiral effective field theory (χ eft ) allow us to bound our theoretical ignorance. in this work, we analyze astrophysical data by using a nonparametric representation of the neutron-star eos conditioned on χ eft to directly constrain the underlying physical properties of the compact objects without introducing modeling systematics. we discuss how the data alone constrain the eos at high densities when we condition on χ eft at low densities. we also demonstrate how to exploit astrophysical data to directly test the predictions of χ eft for the eos up to twice nuclear saturation density, in order to estimate the density at which these predictions might break down. we find that the existence of massive pulsars, gravitational waves from gw 170817 , and nicer observations of psrj0030 +0451 favor χ eft predictions for the eos up to nuclear saturation density over a more agnostic analysis by as much as a factor of seven for the quantum monte carlo (qmc) calculations used in this work. while χ eft predictions using qmc are fully consistent with gravitational-wave data up to twice nuclear saturation density, nicer observations suggest that the eos stiffens relative to these predictions at or slightly above nuclear saturation density. additionally, for these qmc calculations, we marginalize over the uncertainty in the density at which χ eft begins to break down, constraining the radius of a 1.4 m⊙ neutron star to r1.4=11 .40-1.04+1.38 (12 .54-0.63+0.71 ) km and the pressure at twice nuclear saturation density to p (2 nsat) =14 .2-8.4+18.1 (28 .7-15.0+15.3 ) mev /fm3 with massive pulsar and gravitational-wave (and nicer) data. | direct astrophysical tests of chiral effective field theory at supranuclear densities |
the method of geometric deformation (mgd) is here employed to study compact stellar configurations, which are solutions of the effective einstein–dirac coupled field equations on fluid branes. non-linear, self-interacting, fermionic fields are then employed to derive mgd dirac stars, whose properties are analyzed and discussed. the mgd dirac star maximal mass is shown to increase as a specific function of the spinor self-interaction coupling constant, in a realistic model involving the most strict phenomenological current bounds for the brane tension. | mgd dirac stars |
we investigate the possibility that the low mass companion of the black hole in the source of gw190814 was a strange quark star. this possibility is viable within the so-called two-families scenario in which neutron stars and strange quark stars coexist. strange quark stars can reach the mass range indicated by gw190814, m ∼(2.5 - 2.67 ) m⊙ due to a large value of the adiabatic index, without the need for a velocity of sound close to the causal limit. neutron stars (actually hyperonic stars in the two-families scenario) can instead fulfill the presently available astrophysical and nuclear physics constraints which require a softer equation of state. in this scheme it is possible to satisfy both the request of very large stellar masses and of small radii while using totally realistic and physically motivated equations of state. moreover it is possible to get a radius for a 1.4 m⊙ star of the order or less than 11 km, which is impossible if only one family of compact stars exists. | was gw190814 a black hole-strange quark star system? |
the current theoretical development identified as the gravitational decoupling via complete geometric deformation (cgd) method that has been introduced to explore the nonmetricity q effects in relativistic astrophysics. in the present work, we have investigated the gravitationally decoupled anisotropic solutions for the strange stars in the framework of gravity by utilizing the cgd technique. to do this, we started with tolman metric ansatz along with the mit bag model equation of state related to the hadronic matter. the solutions of the governing equations of motions are obtained by using two approaches, namely the mimicking of the θ sector to the seed radial pressure and energy density of the fluid model. the obtained models describe the self-gravitating static, compact objects whose exterior solution can be given by the vacuum schwarzschild anti-de sitter spacetime. in particular, we modeled five stellar candidates, viz., lmc x-4, psr j1614-2230, psr j0740+6620, gw190814, and gw 170817 by using observational data. the rigorous viability tests of the solutions have been performed through regularity and stability conditions. we observed that the nonmetricity parameter and decoupling constant show a significant effect on stabilizing to ensure the physically realizable stellar models. the innovative feature of this work is to present the stable compact objects with masses beyond the without engaging of exotic matter. therefore, the present study shows a new perception and physical significance about the exploration of ultra-compact astrophysical objects.in the present work, the authors have investigated the gravitationally decoupled anisotropic solutions for strange star in the framework of f (q) gravity by utilizing the cgd technique. to do this, they started with tolman metric ansatz along with the mit bag model equation of state related to hadronic matter. the solutions of the governing equations of motions are obtained by using two approaches, namely the mimicking of the θ sector to the seed radial pressure and energy density of the fluid model. the obtained models describe the self-gravitating static, compact objects whose exterior solution can be given by the vacuum schwarzschild anti-de sitter spacetime. in particularly, models are created for five stellar candidates, viz., lmc x-4, psr j1614-2230, psr j0740+6620, gw190814 and gw 170817 by using the observational data. the rigorous viability tests of the solutions have been performed through the regularity and stability conditions. one observes that the nonmetricity parameter and decoupling constant show the significant effect on stabilizing to ensure the physically realizable stellar models. the innovative feature of this work is to present the stable compact objects with the masses beyond the 2m⊙ without engaging of exotic matter. therefore, the present study shows a new perception and physical significance about the exploration of ultra-compact astrophysical objects. | anisotropic strange star model beyond standard maximum mass limit by gravitational decoupling in f(q)f(q) gravity |
we study an impact of self-interacting bosonic dark matter (dm) on various observable properties of neutron stars (nss). the analysis is performed for asymmetric dm with masses from few mev to gev, the self-coupling constant of order o (1 ) and various dm fractions. allowing a mixture between dm and baryonic matter, the formation of a dense dm core or an extended dark halo has been explored. we find that both distribution regimes crucially depend on the mass and fraction of dm for sub-gev boson masses in the strong coupling regime. from the combined analysis of the mass-radius relation and the tidal deformability of compact stars including bosonic dm, we set a stringent constraint on dm fraction. we conclude that observations of 2 m⊙ nss together with λ1.4≤580 constraint, set by ligo/virgo collaboration, favor sub-gev dm particles with low fractions below ∼5 %. | bosonic dark matter in neutron stars and its effect on gravitational wave signal |
context. in the era of large galactic stellar surveys, carefully calibrating and validating the data sets has become an important and integral part of the data analysis. moreover, new generations of stellar atmosphere models and spectral line formation computations need to be subjected to benchmark tests to assess any progress in predicting stellar properties.aims: we focus on cool stars and aim at establishing a sample of 34 gaia fgk benchmark stars with a range of different metallicities. the goal was to determine the effective temperature and the surface gravity independently of spectroscopy and atmospheric models as far as possible. most of the selected stars have been subjected to frequent spectroscopic investigations in the past, and almost all of them have previously been used as reference, calibration, or test objects.methods: fundamental determinations of teff and log g were obtained in a systematic way from a compilation of angular diameter measurements and bolometric fluxes and from a homogeneous mass determination based on stellar evolution models. the derived parameters were compared to recent spectroscopic and photometric determinations and to gravity estimates based on seismic data.results: most of the adopted diameter measurements have formal uncertainties around 1%, which translate into uncertainties in effective temperature of 0.5%. the measurements of bolometric flux seem to be accurate to 5% or better, which contributes about 1% or less to the uncertainties in effective temperature. the comparisons of parameter determinations with the literature in general show good agreements with a few exceptions, most notably for the coolest stars and for metal-poor stars.conclusions: the sample consists of 29 fgk-type stars and 5 m giants. among the fgk stars, 21 have reliable parameters suitable for testing, validation, or calibration purposes. for four stars, future adjustments of the fundamental teff are required, and for five stars the log g determination needs to be improved. future extensions of the sample of gaia fgk benchmark stars are required to fill gaps in parameter space, and we include a list of suggested candidates. | gaia fgk benchmark stars: effective temperatures and surface gravities |
we present models that predict spectra of old- and intermediate-aged stellar populations at 2.51 å (fwhm) with varying [α/fe] abundance. the models are based on the miles library and on corrections from theoretical stellar spectra. the models employ recent [mg/fe] determinations for the miles stars and basti scaled-solar and α-enhanced isochrones. we compute models for a suite of initial mass function (imf) shapes and slopes, covering a wide age/metallicity range. using basti, we also compute `base models' matching the galactic abundance pattern. we confirm that the α-enhanced models show a flux excess with respect to the scaled-solar models blueward ∼4500 å, which increases with age and metallicity. we also confirm that both [mgfe] and [mgfe]' indices are [α/fe]-insensitive. we show that the sensitivity of the higher order balmer lines to [α/fe] resides in their pseudo-continua, with narrower index definitions yielding lower sensitivity. we confirm that the α-enhanced models yield bluer (redder) colours in the blue (red) spectral range. to match optical colours of massive galaxies, we require both α-enhancement and a bottom-heavy imf. the comparison of globular cluster line-strengths with our predictions match the [mg/fe] determinations from their individual stars. we obtain good fits to both full spectra and indices of galaxies with varying [α/fe]. using thousands of sdss galaxy spectra, we obtain a linear relation between a proxy for the abundance, [zmg/zfe]ss(basti), using solely scaled-solar models and the [mg/fe] derived with models with varying abundance ([mg/fe] = 0.59[zmg/zfe]ss(basti)). finally, we provide a user-friendly, web-based facility, which allows composite populations with varying imf and [α/fe]. | evolutionary stellar population synthesis with miles - ii. scaled-solar and α-enhanced models |
we present an analysis of [o i]63, [o iii]88, [n ii]122, and [c ii]158 far-infrared (fir) fine-structure line observations obtained with herschel/pacs, for ∼240 local luminous infrared galaxies (lirgs) in the great observatories all-sky lirg survey. we find pronounced declines ("deficits") of line-to-fir continuum emission for [n ii]122, [o i]63, and [c ii]158 as a function of fir color and infrared luminosity surface density, σir. the median electron density of the ionized gas in lirgs, based on the [n ii]122/[n ii]205 ratio, is ne = 41 cm-3. we find that the dispersion in the [c ii]158 deficit of lirgs is attributed to a varying fractional contribution of photodissociation regions (pdrs) to the observed [c ii]158 emission, f([c ii]158pdr) = [c ii]158pdr/[c ii]158, which increases from ∼60% to ∼95% in the warmest lirgs. the [o i]63/[c ii]158pdr ratio is tightly correlated with the pdr gas kinetic temperature in sources where [o i]63 is not optically thick or self-absorbed. for each galaxy, we derive the average pdr hydrogen density, nh, and intensity of the interstellar radiation field, g, in units of g0 and find g/nh ratios of ∼0.1-50 g0 cm3, with ulirgs populating the upper end of the distribution. there is a relation between g/nh and σ ir, showing a critical break at σir* ≃ 5 × 1010 l⊙ kpc-2. below σir*, g/nh remains constant, ≃0.32 g0 cm3, and variations in σir are driven by the number density of star-forming regions within a galaxy, with no change in their pdr properties. above σ ir*, g/nh increases rapidly with σir, signaling a departure from the typical pdr conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources. | a herschel/pacs far-infrared line emission survey of local luminous infrared galaxies |
the deformability of a compact object induced by a perturbing tidal field is encoded in the tidal love numbers, which depend sensibly on the object's internal structure. these numbers are known only for static, spherically-symmetric objects. as a first step to compute the tidal love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. the spin of the object introduces couplings between electric and magnetic deformations and new classes of induced love numbers emerge. for example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. the deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. we discuss certain subtleties in defining the tidal love numbers in general relativity, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution, even in the static case. by extending the standard procedure to identify the linear response in the static case, we prove analytically that the love numbers of a kerr black hole remain zero to second order in the spin. as a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties. | tidal deformations of a spinning compact object |
the asteroid terrestrial-impact last alert system (atlas) observes most of the sky every night in search of dangerous asteroids. its data are also used to search for photometric variability, where sensitivity to variability is limited by photometric accuracy. since each exposure spans 7.°6 corner to corner, variations in atmospheric transparency in excess of 0.01 mag are common, and 0.01 mag photometry cannot be achieved by using a constant flat-field calibration image. we therefore have assembled an all-sky reference catalog of approximately one billion stars to m ∼ 19 from a variety of sources to calibrate each exposure’s astrometry and photometry. gaia dr2 is the source of astrometry for this atlas refcat2. the sources of g, r, i, and z photometry include pan-starrs dr1, the atlas pathfinder photometry project, atlas reflattened apass data, skymapper dr1, apass dr9, the tycho-2 catalog, and the yale bright star catalog. we have attempted to make this catalog at least 99% complete to m < 19, including the brightest stars in the sky. we believe that the systematic errors are no larger than 5 mmag rms, although errors are as large as 20 mmag in small patches near the galactic plane. | the atlas all-sky stellar reference catalog |
using the binary population and spectral synthesis code, bpass, we have calculated the rates, time-scales and mass distributions for binary black hole (bh) mergers as a function of metallicity. we consider these in the context of the recently reported first laser interferometer gravitational-wave observatory (ligo) event detection. we find that the event has a very low probability of arising from a stellar population with initial metallicity mass fraction above z = 0.010 (z ≳ 0.5 z⊙). binary bh merger events with the reported masses are most likely in populations below 0.008 (z ≲ 0.4 z⊙). events of this kind can occur at all stellar population ages from 3 myr up to the age of the universe, but constitute only 0.1-0.4 per cent of binary bh mergers between metallicities of z = 0.001 and 0.008. however at metallicity z = 10-4, 26 per cent of binary bh mergers would be expected to have the reported masses. at this metallicity, the progenitor merger times can be close to ≈10 gyr and rotationally mixed stars evolving through quasi-homogeneous evolution, due to mass transfer in a binary, dominate the rate. the masses inferred for the bhs in the binary progenitor of gw 150914 are amongst the most massive expected at anything but the lowest metallicities in our models. we discuss the implications of our analysis for the electromagnetic follow-up of future ligo event detections. | bpass predictions for binary black hole mergers |
we constrain the hubble constant h0 using fast radio burst (frb) observations from the australian square kilometre array pathfinder (askap) and murriyang (parkes) radio telescopes. we use the redshift-dispersion measure ('macquart') relationship, accounting for the intrinsic luminosity function, cosmological gas distribution, population evolution, host galaxy contributions to the dispersion measure (dmhost), and observational biases due to burst duration and telescope beamshape. using an updated sample of 16 askap frbs detected by the commensal real-time askap fast transients (craft) survey and localized to their host galaxies, and 60 unlocalized frbs from parkes and askap, our best-fitting value of h0 is calculated to be $73_{-8}^{+12}$ km s-1 mpc-1. uncertainties in frb energetics and dmhost produce larger uncertainties in the inferred value of h0 compared to previous frb-based estimates. using a prior on h0 covering the 67-74 km s-1 mpc-1 range, we estimate a median ${\rm dm}_{\rm host}= 186_{-48}^{+59}\,{\rm pc \, cm^{-3}}$, exceeding previous estimates. we confirm that the frb population evolves with redshift similarly to the star-formation rate. we use a schechter luminosity function to constrain the maximum frb energy to be log10emax$=41.26_{-0.22}^{+0.27}$ erg assuming a characteristic frb emission bandwidth of 1 ghz at 1.3 ghz, and the cumulative luminosity index to be $\gamma =-0.95_{-0.15}^{+0.18}$. we demonstrate with a sample of 100 mock frbs that h0 can be measured with an uncertainty of ±2.5 km s-1 mpc-1, demonstrating the potential for clarifying the hubble tension with an upgraded askap frb search system. last, we explore a range of sample and selection biases that affect frb analyses. | a measurement of hubble's constant using fast radio bursts |
context. rr lyrae stars are excellent tracers of the oldest stars (ages ≳ 9-10 gyr) and standard candles for measuring the distance to stellar systems that are mainly composed of an old stellar population. the gaia third data release (dr3) publishes a catalogue of full-sky rr lyrae stars observed during the initial 34 months of science operations. they were processed through the specific object study (sos) pipeline, which was developed to validate and characterise cepheids and rr lyrae stars (sos cep&rrl) observed by gaia.aims: the main steps of the sos cep&rrl pipeline are described in the documentation and papers accompanying previous gaia data releases. for dr3, the pipeline was modified in its process: in addition to the gaia multiband (g, gbp, grp) time-series photometry, the epoch radial velocities measured for rr lyrae and cepheids with the radial velocity spectrometer (rvs) on board gaia were also processed through the pipeline.methods: the sos cep&rrl validation of dr3 candidate rr lyrae stars relies on diagnostics tools that include the period versus g-amplitude diagram and the period versus ϕ21 and ϕ31 parameters of the g light-curve fourier decomposition, as defined by a reference sample of bona fide rr lyrae stars known in the literature (that we named gold sample). great care was devoted to building a large and pure gold sample comprising more than 200 000 rr lyrae stars. the sos processing led to an initial catalogue of 271779 rr lyrae stars that are listed in the vari_rrlyrae table of the dr3 archive. a thorough cleaning procedure was then performed to produce a final catalogue of sos-confirmed dr3 rr lyrae stars by dropping sources that clearly are contaminants or have an uncertain classification.results: multiband time-series photometry and characterisation are published in gaia dr3 for a clean, validated sample of 270 905 rr lyrae stars (174 947 fundamental-mode, 93 952 first-overtone, and 2006 double-mode rr lyrae) that were confirmed and fully characterised by the sos cep&rrl pipeline. they are distributed throughout the sky, including variables in 95 globular clusters and 25 milky way (mw) companions (the magellanic clouds, seven dwarf spheroidal galaxies, and 16 ultra-faint dwarf satellites of the mw). rvs time-series radial velocities are also published for 1096 rr lyrae and 799 cepheids of different types (classical, anomalous, and type ii cepheids). of the 270 905 dr3 rr lyrae stars, 200 294 are already known in the literature (gold sample) and 70 611 are new discoveries by gaia, to the best of our knowledge. an estimate of the interstellar absorption is published for 142 660 fundamental-mode rr lyrae stars from a relation based on the g-band amplitude, the (g − grp) colour and the pulsation period. metallicities derived from the fourier parameters of the light curves are also released for 133 559 rr lyrae stars.conclusions: the final gaia dr3 catalogue of confirmed rr lyrae stars almost doubles the dr2 rr lyrae catalogue. an increase in statistical significance, a better characterisation of the rr lyrae pulsational and astrophysical parameters, and the improved astrometry published with gaia edr3 make the sos cep&rrl dr3 sample the largest, most homogeneous, and parameter-richest catalogue of all-sky rr lyrae stars published so far in the magnitude range from ⟨g⟩=7.64 mag (the magnitude of rr lyr itsef, the class prototype) to ⟨g⟩=21.14 mag (the faintest rr lyrae in the catalogue). full tables 2, 5-9, a.1-a.2, and lightcurves are only available at the cds via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/j/a+a/674/a18 | gaia data release 3. specific processing and validation of all-sky rr lyrae and cepheid stars: the rr lyrae sample |
the maximal arnowitt-deser-misner (adm) mass for (mini)boson stars (bss)—gravitating solitons of einstein's gravity minimally coupled to a free, complex, mass μ , klein-gordon field—is madmmax∼mpl2/μ . adding quartic self-interactions to the scalar field theory, described by the lagrangian li=λ |ψ |4 , the maximal adm mass becomes madmmax∼√{λ }mpl3/μ2 . thus, for mini-bss, astrophysically interesting masses require ultralight scalar fields, whereas self-interacting bss can reach such values for bosonic particles with standard model range masses. we investigate how these same self-interactions affect kerr black holes with scalar hair (kbhssh) [c. a. r. herdeiro and e. radu, kerr black holes with scalar hair, phys. rev. lett. 112, 221101 (2014).], which can be regarded as (spinning) bss in stationary equilibrium with a central horizon. remarkably, whereas the adm mass scales in the same way as for bss, the horizon mass mh does not increases with the coupling λ , and, for fixed μ , it is maximized at the "hod point," corresponding to the extremal kerr black hole obtained in the vanishing hair limit. this mass is always mhmax∼mpl2/μ . thus, introducing these self-interactions, the black hole spacetimes may become considerably "hairier" but the trapped regions cannot become "heavier." we present evidence that this observation also holds in a model with li=β |ψ |6-λ |ψ |4 ; if it extends to general scalar field models, kbhssh with astrophysically interesting horizon masses require ultralight scalar fields. their existence, therefore, would be a smoking gun for such (beyond the standard model) particles. | kerr black holes with self-interacting scalar hair: hairier but not heavier |
pair instability (pi) and pulsational pi prevent the formation of black holes (bhs) with mass ≳60 m⊙ from single star evolution. here, we investigate the possibility that bhs with mass in the pi gap form via stellar mergers and multiple stellar mergers, facilitated by dynamical encounters in young star clusters. we analyse 104 simulations, run with the direct n-body code nbody6++gpu coupled with the population synthesis code mobse. we find that up to ∼6 per cent of all simulated bhs have mass in the pi gap, depending on progenitor's metallicity. this formation channel is strongly suppressed in metal-rich (z = 0.02) star clusters because of stellar winds. bhs with mass in the pi gap are initially single bhs but can efficiently acquire companions through dynamical exchanges. we find that ∼21 per cent, 10 per cent, and 0.5 per cent of all binary bhs have at least one component in the pi mass gap at metallicity z = 0.0002, 0.002, and 0.02, respectively. based on the evolution of the cosmic star formation rate and metallicity, and under the assumption that all stars form in young star clusters, we predict that ∼5 per cent of all binary bh mergers detectable by advanced ligo and virgo at their design sensitivity have at least one component in the pi mass gap. | binary black holes in the pair instability mass gap |
we have performed ab initio neutrino radiation hydrodynamics simulations in three and two spatial dimensions (3d and 2d) of core-collapse supernovae from the same 15 m ⊙ progenitor through 440 ms after core bounce. both 3d and 2d models achieve explosions; however, the onset of explosion (shock revival) is delayed by ∼100 ms in 3d relative to the 2d counterpart and the growth of the diagnostic explosion energy is slower. this is consistent with previously reported 3d simulations utilizing iron-core progenitors with dense mantles. in the ∼100 ms before the onset of explosion, diagnostics of neutrino heating and turbulent kinetic energy favor earlier explosion in 2d. during the delay, the angular scale of convective plumes reaching the shock surface grows and explosion in 3d is ultimately lead by a single, large-angle plume, giving the expanding shock a directional orientation not dissimilar from those imposed by axial symmetry in 2d simulations. we posit that shock revival and explosion in the 3d simulation may be delayed until sufficiently large plumes form, whereas such plumes form more rapidly in 2d, permitting earlier explosions. | three-dimensional core-collapse supernova simulated using a 15 m ⊙ progenitor |
feedback from energy liberated by gas accretion on to black holes (bhs) is an attractive mechanism to explain the exponential cut-off at the massive end of the galaxy stellar mass function. most previous implementations of bh accretion in hydrodynamical simulations of galaxy formation have assumed that bhs grow at an accretion rate that is proportion to the bondi rate. a major concern is that the bondi accretion rate is inappropriate when the accreting material has significant angular momentum. we present an improved accretion model that takes into account the circularization and subsequent viscous transport of infalling material, and implemented as a `subgrid' model in hydrodynamic simulations. the resulting accretion rates are generally low in low mass (≲ 1011.5 m⊙) haloes, but show outbursts of eddington-limited accretion during galaxy mergers. during outbursts these objects strongly resemble quasars. in higher mass haloes, gas accretion peaks at ∼10 per cent of the eddington rate, which is thought to be conducive to the formation of radio jets. the resulting accretion rate depends strongly on the effective pressure of the gas surrounding the bh, which in turn depends strongly on halo mass. this induces a sharp transition in the importance of bh feedback. in small haloes, the growth of galaxies is regulated by star formation and supernova feedback, but above a halo mass of 1011.5 m⊙, rapid bh growth leads to the suppression of star formation and reduced growth of stellar mass with increasing halo mass. | the impact of angular momentum on black hole accretion rates in simulations of galaxy formation |
several thousand core-collapse supernovae (ccsne) of different flavors have been discovered so far. however, identifying their progenitors has remained an outstanding open question in astrophysics. studies of sn host galaxies have proven to be powerful in providing constraints on the progenitor populations. in this paper, we present all ccsne detected between 2009 and 2017 by the palomar transient factory. this sample includes 888 sne of 12 distinct classes out to redshift z ≈ 1. we present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. the galaxy mass function of type ic, ib, iib, ii, and iin sne ranges from 105 to 1011.5 m⊙, probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. regular ccsne are hence direct tracers of star formation. small but notable differences exist between some of the sn classes. type ib/c sne prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than type iib and ii sne. these differences are less pronounced than previously thought. h-poor superluminous supernovae (slsne) and sne ic-bl are scarce in galaxies above 1010 m⊙. their progenitors require environments with metallicities of < 0.4 and < 1 solar, respectively. in addition, the hosts of h-poor slsne are dominated by a younger stellar population than all other classes of ccsne. our findings corroborate the notion that low metallicity and young age play an important role in the formation of slsn progenitors. | the palomar transient factory core-collapse supernova host-galaxy sample. i. host-galaxy distribution functions and environment dependence of core-collapse supernovae |
mid-infrared (mid-ir) observations are powerful in identifying heavily obscured active galactic nuclei (agn) that have weak emission in other wavelengths. data from the mid-infrared instrument (miri) on board the james webb space telescope provides an excellent opportunity to perform such studies. we take advantage of the miri imaging data from the cosmic evolution early release science survey to investigate the agn population in the distant universe. we estimate the source properties of miri-selected objects by utilizing spectral energy distribution (sed) modeling, and classify them into star-forming galaxies (sfs), sf-agn mixed objects, and agn. the source numbers of these types are 433, 102, and 25, respectively, from four miri pointings covering ~9 arcmin2. the sample spans a redshift range of ≈0-5. we derive the median seds for all three source types, respectively, and publicly release them. the median miri sed of agn is similar to the typical seds of hot dust-obscured galaxies and seyfert 2s, for which the mid-ir seds are dominated by emission from agn-heated hot dust. based on our sed-fit results, we estimate the black hole accretion density (bhad; i.e., total bh growth rate per comoving volume) as a function of redshift. at z < 3, the resulting bhad agrees with the x-ray measurements in general. at z > 3, we identify a total of 27 agn and sf-agn mixed objects, leading to that our high-z bhad is substantially higher than the x-ray results (~0.5 dex at z ≈ 3-5). this difference indicates miri can identify a large population of heavily obscured agn missed by x-ray surveys at high redshifts. | ceers key paper. vi. jwst/miri uncovers a large population of obscured agn at high redshifts |
the existence of localized, approximately stationary, lumps of the classical gravitational and electromagnetic field - geons - was conjectured more than half a century ago. if one insists on exact stationarity, topologically trivial configurations in electro-vacuum are ruled out by no-go theorems for solitons. but stationary, asymptotically flat geons found a realization in scalar-vacuum, where everywhere non-singular, localized field lumps exist, known as (scalar) boson stars. similar geons have subsequently been found in einstein-dirac theory and, more recently, in einstein-proca theory. we identify the common conditions that allow these solutions, which may also exist for other spin fields. moreover, we present a comparison of spherically symmetric geons for the spin 0 , 1 / 2 and 1, emphasizing the mathematical similarities and clarifying the physical differences, particularly between the bosonic and fermionic cases. we clarify that for the fermionic case, pauli's exclusion principle prevents a continuous family of solutions for a fixed field mass; rather only a discrete set exists, in contrast with the bosonic case. | asymptotically flat scalar, dirac and proca stars: discrete vs. continuous families of solutions |
wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (mpeak < -18), blue transients. while commonly attributed to the breakout of a supernova shock into a dense wind, the great distances to the transients of this class found so far have hampered detailed investigation of their properties. we present photometry and spectroscopy from a comprehensive worldwide campaign to observe at 2018cow (atlas 18qqn), the first fast-luminous optical transient to be found in real time at low redshift. our first spectra (<2 days after discovery) are entirely featureless. a very broad absorption feature suggestive of near-relativistic velocities develops between 3 and 8 days, then disappears. broad emission features of h and he develop after >10 days. the spectrum remains extremely hot throughout its evolution, and the photospheric radius contracts with time (receding below r < 1014 cm after 1 month). this behaviour does not match that of any known supernova, although a relativistic jet within a fallback supernova could explain some of the observed features. alternatively, the transient could originate from the disruption of a star by an intermediate-mass black hole, although this would require long-lasting emission of highly super-eddington thermal radiation. in either case, at 2018cow suggests that the population of fast luminous transients represents a new class of astrophysical event. intensive follow-up of this event in its late phases, and of any future events found at comparable distance, will be essential to better constrain their origins. | the fast, luminous ultraviolet transient at2018cow: extreme supernova, or disruption of a star by an intermediate-mass black hole? |
the study of stellar surfaces can reveal information about the chemical composition, interior structure, and magnetic properties of stars. it is also critical to the detection and characterization of extrasolar planets, in particular those targeted in extreme precision radial velocity (eprv) searches, which must contend with stellar variability that is often orders of magnitude stronger than the planetary signal. one of the most successful methods to map the surfaces of stars is doppler imaging, in which the presence of inhomogeneities is inferred from subtle line shape changes in high resolution stellar spectra. in this paper, we present a novel, efficient, and closed-form solution to the problem of doppler imaging of stellar surfaces. our model explicitly allows for incomplete knowledge of the local (rest frame) stellar spectrum, allowing one to learn differences from spectral templates while simultaneously mapping the stellar surface. it therefore works on blended lines, regions of the spectrum where line formation mechanisms are not well understood, or stars whose spots have intrinsically different spectra from the rest of the photosphere. we implement the model within the open source starry framework, making it fast, differentiable, and easy to use in both optimization and posterior inference settings. as a proof-of-concept, we use our model to infer the surface map of the brown dwarf wise 1049-5319b, finding close agreement with the solution of crossfield et al. (2014). we also discuss doppler imaging in the context of eprv studies and describe an interpretable spectral-temporal gaussian process for stellar spectral variability that we expect will be important for eprv exoplanet searches. | mapping stellar surfaces iii: an efficient, scalable, and open-source doppler imaging model |
we characterize mass, momentum, energy, and metal outflow rates of multiphase galactic winds in a suite of fire-2 cosmological 'zoom-in' simulations from the feedback in realistic environments (fire) project. we analyse simulations of low-mass dwarfs, intermediate-mass dwarfs, milky way-mass haloes, and high-redshift massive haloes. consistent with previous work, we find that dwarfs eject about 100 times more gas from their interstellar medium (ism) than they form in stars, while this mass 'loading factor' drops below one in massive galaxies. most of the mass is carried by the hot phase (>105 k) in massive haloes and the warm phase (103-105 k) in dwarfs; cold outflows (<103 k) are negligible except in high-redshift dwarfs. energy, momentum, and metal loading factors from the ism are of order unity in dwarfs and significantly lower in more massive haloes. hot outflows have 2-5 × higher specific energy than needed to escape from the gravitational potential of dwarf haloes; indeed, in dwarfs, the mass, momentum, and metal outflow rates increase with radius whereas energy is roughly conserved, indicating swept up halo gas. burst-averaged mass loading factors tend to be larger during more powerful star formation episodes and when the inner halo is not virialized, but we see effectively no trend with the dense ism gas fraction. we discuss how our results can guide future controlled numerical experiments that aim to elucidate the key parameters governing galactic winds and the resulting associated preventative feedback. | characterizing mass, momentum, energy, and metal outflow rates of multiphase galactic winds in the fire-2 cosmological simulations |
we present the full public data release (pdr-2) of the vimos public extragalactic redshift survey (vipers), performed at the eso vlt. we release redshifts, spectra, cfhtls magnitudes and ancillary information (as masks and weights) for a complete sample of 86 775 galaxies (plus 4732 other objects, including stars and serendipitous galaxies); we also include their full photometrically-selected parent catalogue. the sample is magnitude limited to iab ≤ 22.5, with an additional colour-colour pre-selection devised as to exclude galaxies at z < 0.5. this practically doubles the effective sampling of the vimos spectrograph over the range 0.5 < z < 1.2 (reaching 47% on average), yielding a final median local galaxy density close to 5 × 10-3h3 mpc-3. the total area spanned by the final data set is ≃ 23.5 deg2, corresponding to 288 vimos fields with marginal overlaps, split over two regions within the cfhtls-wide w1 and w4 equatorial fields (at ra ≃ 2 and ≃ 22 h, respectively). spectra were observed at a resolution r = 220, covering a wavelength range 5500-9500 å. data reduction and redshift measurements were performed through a fully automated pipeline; all redshift determinations were then visually validated and assigned a quality flag. measurements with a quality flag ≥ 2 are shown to have a confidence level of 96% or larger and make up 88% of all measured galaxy redshifts (76 552 out of 86 775), constituting the vipers prime catalogue for statistical investigations. for this sample the rms redshift error, estimated using repeated measurements of about 3000 galaxies, is found to be σz = 0.00054(1 + z). all data are available at <ext-link ext-link-type="uri" xlink:href="http://vipers.inaf.it">http://vipers.inaf.it</ext-link> and on the eso archive. based on observations collected at the european southern observatory, cerro paranal, chile, using the very large telescope under programmes 182.a-0886 and partly 070.a-9007. also based on observations obtained with megaprime/megacam, a joint project of cfht and cea/dapnia, at the canada-france-hawaii telescope (cfht), which is operated by the national research council (nrc) of canada, the institut national des sciences de l'univers of the centre national de la recherche scientifique (cnrs) of france, and the university of hawaii. this work is based in part on data products produced at terapix and the canadian astronomy data centre as part of the canada-france-hawaii telescope legacy survey, a collaborative project of nrc and cnrs. the vipers web site is http://www.vipers.inaf.it/ | the vimos public extragalactic redshift survey (vipers). full spectroscopic data and auxiliary information release (pdr-2) |
we present a suite of seven 3d supernova simulations of non-rotating low-mass progenitors using multigroup neutrino transport. our simulations cover single star progenitors with zero-age main-sequence masses between 9.6 and 12.5 m_⊙ and (ultra)stripped-envelope progenitors with initial helium core masses between 2.8 and 3.5 m_⊙. we find explosion energies between 0.1 and 0.4 bethe, which are still rising by the end of the simulations. although less energetic than typical events, our models are compatible with observations of less energetic explosions of low-mass progenitors. in six of our models, the mass outflow rate already exceeds the accretion rate on to the proto-neutron star, and the mass and angular momentum of the compact remnant have closely approached their final value, barring the possibility of later fallback. while the proto-neutron star is still accelerated by the gravitational tug of the asymmetric ejecta, the acceleration can be extrapolated to obtain estimates for the final kick velocity. we obtain gravitational neutron star masses between 1.22 and 1.44 m_⊙, kick velocities between 11 and 695 km s^{-1}, and spin periods from 20 ms to 2.7 s, which suggest that typical neutron star birth properties can be naturally obtained in the neutrino-driven paradigm. we find a loose correlation between the explosion energy and the kick velocity. there is no indication of spin-kick alignment, but a correlation between the kick velocity and the neutron star angular momentum, which needs to be investigated further as a potential point of tension between models and observations. | three-dimensional simulations of neutrino-driven core-collapse supernovae from low-mass single and binary star progenitors |
recently there has been significant interest in the claim that dark matter axions gravitationally thermalize and form a bose-einstein condensate with a cosmologically long-range correlation. this has potential consequences for galactic scale observations. here we critically examine this claim. we point out that there is an essential difference between the thermalization and formation of a condensate due to repulsive interactions, which can indeed drive long-range order, and that due to attractive interactions, which can lead to localized bose clumps (stars or solitons) that only exhibit short-range correlation. while the difference between repulsion and attraction is not present in the standard collisional boltzmann equation, we argue that it is essential to the field theory dynamics, and we explain why the latter analysis is appropriate for a condensate. since the axion is primarily governed by attractive interactions—gravitation and scalar-scalar contact interactions—we conclude that while a bose-einstein condensate is formed, the claim of long-range correlation is unjustified. | do dark matter axions form a condensate with long-range correlation? |
this paper describes a new publicly available codebase for modeling galaxy formation in a cosmological context, the “semi-analytic galaxy evolution” model, or sage for short.5 sage is a significant update to the 2006 model of croton et al. and has been rebuilt to be modular and customizable. the model will run on any n-body simulation whose trees are organized in a supported format and contain a minimum set of basic halo properties. in this work, we present the baryonic prescriptions implemented in sage to describe the formation and evolution of galaxies, and their calibration for three n-body simulations: millennium, bolshoi, and gigglez. updated physics include the following: gas accretion, ejection due to feedback, and reincorporation via the galactic fountain; a new gas cooling-radio mode active galactic nucleus (agn) heating cycle; agn feedback in the quasar mode; a new treatment of gas in satellite galaxies; and galaxy mergers, disruption, and the build-up of intra-cluster stars. throughout, we show the results of a common default parameterization on each simulation, with a focus on the local galaxy population. | semi-analytic galaxy evolution (sage): model calibration and basic results |
we compare the predictions of horizon-agn, a hydrodynamical cosmological simulation that uses an adaptive mesh refinement code, to observational data in the redshift range 0 < z < 6. we study the reproduction, by the simulation, of quantities that trace the aggregate stellar-mass growth of galaxies over cosmic time: luminosity and stellar-mass functions, the star formation main sequence, rest-frame uv-optical-near-infrared colours and the cosmic star formation history. we show that horizon-agn, which is not tuned to reproduce the local universe, produces good overall agreement with these quantities, from the present day to the epoch when the universe was 5 per cent of its current age. by comparison to horizon-noagn, a twin simulation without active galactic nuclei feedback, we quantify how feedback from black holes is likely to help shape galaxy stellar-mass growth in the redshift range 0 < z < 6, particularly in the most massive galaxies. our results demonstrate that horizon-agn successfully captures the evolutionary trends of observed galaxies over the lifetime of the universe, making it an excellent tool for studying the processes that drive galaxy evolution and making predictions for the next generation of galaxy surveys. | the horizon-agn simulation: evolution of galaxy properties over cosmic time |
in the current article, we study anisotropic spherically symmetric strange star under the background of f(r, t) gravity using the metric potentials of tolman-kuchowicz type (tolman in phys rev 55:364, 1939; kuchowicz in acta phys pol 33:541, 1968) as λ (r ) =ln(1 +a r2+b r4) and ν (r ) =b r2+2 lnc which are free from singularity, satisfy stability criteria and also well-behaved. we calculate the value of constants a, b, b and c using matching conditions and the observed values of the masses and radii of known samples. to describe the strange quark matter (sqm) distribution, here we have used the phenomenological mit bag model equation of state (eos) where the density profile (ρ ) is related to the radial pressure (pr) as pr(r ) =1/3 (ρ -4 bg) . here quark pressure is responsible for generation of bag constant bg. motivation behind this study lies in finding out a non-singular physically acceptable solution having various properties of strange stars. the model shows consistency with various energy conditions, tov equation, herrera's cracking condition and also with harrison-zel'dovich-novikov's static stability criteria. numerical values of eos parameter and the adiabatic index also enhance the acceptability of our model. | anisotropic strange star with tolman-kuchowicz metric under f(r, t) gravity |
both the co(2-1) and co(1-0) lines are used to trace the mass of molecular gas in galaxies. translating the molecular gas mass estimates between studies using different lines requires a good understanding of the behaviour of the co(2-1)-to-co(1-0) ratio, r21. we compare new, high-quality co(1-0) data from the iram 30-m emir multiline probe of the ism regulating galaxy evolution survey to the latest available co(2-1) maps from hera co-line extragalactic survey, physics at high angular resolution in nearby galaxies-alma, and a new iram 30-m m51 large program. this allows us to measure r21 across the full star-forming disc of nine nearby, massive, star-forming spiral galaxies at 27 arcsec (~1-2 kpc) resolution. we find an average r21 = 0.64 ± 0.09 when we take the luminosity-weighted mean of all individual galaxies. this result is consistent with the mean ratio for disc galaxies that we derive from single-pointing measurements in the literature, $r_{\rm 21, lit}~=~0.59^{+0.18}_{-0.09}$. the ratio shows weak radial variations compared to the point-to-point scatter in the data. in six out of nine targets, the central enhancement in r21 with respect to the galaxy-wide mean is of order of ${\sim}10{-}20{{\ \rm per\ cent}}$. we estimate an azimuthal scatter of ~20 per cent in r21 at fixed galactocentric radius but this measurement is limited by our comparatively coarse resolution of 1.5 kpc. we find mild correlations between r21 and carbon monoxide (co) brightness temperature, infrared (ir) intensity, 70-160 µm ratio, and ir-to-co ratio. all correlations indicate that r21 increases with gas surface density, star formation rate surface density, and the interstellar radiation field. | new constraints on the 12co(2-1)/(1-0) line ratio across nearby disc galaxies |
the past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. while these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (bhs). we investigate the impact of the sub-grid models on the bh mass properties of the illustris, tng100, tng300, horizon-agn, eagle, and simba simulations, focusing on the mbh - m⋆ relation and the bh mass function. all simulations predict tight mbh - m⋆ relations, and struggle to produce bhs of $m_{\rm bh}\leqslant 10^{7.5}\, \rm m_{\odot }$ in galaxies of $m_{\star }\sim 10^{10.5}\!-\!10^{11.5}\, \rm m_{\odot }$. while the time evolution of the mean mbh - m⋆ relation is mild ($\rm \delta m_{\rm bh}\leqslant 1\, dex$ for 0 $\leqslant z \leqslant$ 5) for all the simulations, its linearity (shape) and normalization varies from simulation to simulation. the strength of sn feedback has a large impact on the linearity and time evolution for $m_{\star }\leqslant 10^{10.5}\, \rm m_{\odot }$. we find that the low-mass end is a good discriminant of the simulation models, and highlights the need for new observational constraints. at the high-mass end, strong agn feedback can suppress the time evolution of the relation normalization. compared with observations of the local universe, we find an excess of bhs with $m_{\rm bh}\geqslant 10^{9}\, \rm m_{\odot }$ in most of the simulations. the bh mass function is dominated by efficiently accreting bhs ($\log _{10}\, f_{\rm edd}\geqslant -2$) at high redshifts, and transitions progressively from the high-mass to the low-mass end to be governed by inactive bhs. the transition time and the contribution of active bhs are different among the simulations, and can be used to evaluate models against observations. | supermassive black holes in cosmological simulations i: mbh - m⋆ relation and black hole mass function |
in certain models of a qcd axion, finite density corrections to the axion potential can result in the axion being sourced by large dense objects. there are a variety of ways to test this phenomenon, but perhaps the most surprising effect is that the axion can mediate forces between neutron stars that can be as strong as gravity. these forces can be attractive or repulsive and their presence can be detected by advanced ligo observations of neutron star inspirals. by a numerical coincidence, axion forces between neutron stars with gravitational strength naturally have an associated length scale of tens of kilometers or longer, similar to that of a neutron star. future observations of neutron star mergers in advanced ligo can probe many orders of magnitude of axion parameter space. because the axion is only sourced by large dense objects, the axion force evades fifth force constraints. we also outline several other ways to probe this phenomenon using electromagnetic signals associated with compact objects. | probing axions with neutron star inspirals and other stellar processes |
we present the survey strategy and early results of the “satellites around galactic analogs” (saga) survey. the saga survey’s goal is to measure the distribution of satellite galaxies around 100 systems analogous to the milky way down to the luminosity of the leo i dwarf galaxy ({m}r< -12.3). we define a milky way analog based on k-band luminosity and local environment. here, we present satellite luminosity functions for eight milky-way-analog galaxies between 20 and 40 mpc. these systems have nearly complete spectroscopic coverage of candidate satellites within the projected host virial radius down to {r}o< 20.75 using low-redshift gri color criteria. we have discovered a total of 25 new satellite galaxies: 14 new satellite galaxies meet our formal criteria around our complete host systems, plus 11 additional satellites in either incompletely surveyed hosts or below our formal magnitude limit. combined with 13 previously known satellites, there are a total of 27 satellites around 8 complete milky-way-analog hosts. we find a wide distribution in the number of satellites per host, from 1 to 9, in the luminosity range for which there are 5 milky way satellites. standard abundance matching extrapolated from higher luminosities predicts less scatter between hosts and a steeper luminosity function slope than observed. we find that the majority of satellites (26 of 27) are star-forming. these early results indicate that the milky way has a different satellite population than typical in our sample, potentially changing the physical interpretation of measurements based only on the milky way’s satellite galaxies. | the saga survey. i. satellite galaxy populations around eight milky way analogs |
we present the full catalog of young stellar objects (ysos) identified in the 18 molecular clouds surveyed by the spitzer space telescope “cores to disks” (c2d) and “gould belt” (gb) legacy surveys. using standard techniques developed by the c2d project, we identify 3239 candidate ysos in the 18 clouds, 2966 of which survive visual inspection and form our final catalog of ysos in the gb. we compile extinction corrected spectral energy distributions for all 2966 ysos and calculate and tabulate the infrared spectral index, bolometric luminosity, and bolometric temperature for each object. we find that 326 (11%), 210 (7%), 1248 (42%), and 1182 (40%) are classified as class 0 + i, flat-spectrum, class ii, and class iii, respectively, and show that the class iii sample suffers from an overall contamination rate by background asymptotic giant branch stars between 25% and 90%. adopting standard assumptions, we derive durations of 0.40-0.78 myr for class 0 + i ysos and 0.26-0.50 myr for flat-spectrum ysos, where the ranges encompass uncertainties in the adopted assumptions. including information from (sub)millimeter wavelengths, one-third of the class 0 + i sample is classified as class 0, leading to durations of 0.13-0.26 myr (class 0) and 0.27-0.52 myr (class i). we revisit infrared color-color diagrams used in the literature to classify ysos and propose minor revisions to classification boundaries in these diagrams. finally, we show that the bolometric temperature is a poor discriminator between class ii and class iii ysos. | young stellar objects in the gould belt |
we perform a comprehensive study of the x-ray emission from 70 transient sources that have been classified as tidal disruption events (tdes) in the literature. we explore the properties of these candidates, using nearly three decades of x-ray observations to quantify their properties and characteristics. we find that the emission from x-ray tdes increase by two to three orders of magnitude, compared to pre-flare constraints. these emissions evolve significantly with time, and decay with power-law indices that are typically shallower than the canonical t -5/3 decay law, implying that x-ray tdes are viscously delayed. these events exhibit enhanced (relative to galactic) column densities and are quite soft in nature, with no strong correlation between the amount of detected soft and hard emission. at their peak, jetted events have an x-ray to optical ratio ≫1, whereas non-jetted events have a ratio ∼1, which suggests that these events undergo reprocessing at different rates. x-ray tdes have long t 90 values, consistent with what would be expected from a viscously driven accretion disk formed by the disruption of a main-sequence star by a black hole with a mass <107 m ⊙. the isotropic luminosities of x-ray tdes are bimodal, such that jetted and non-jetted events are separated by a “reprocessing valley” that we suggest is naturally populated by optical/uv tdes that most likely produce x-rays, but this emission is “veiled” from observations due to reprocessing. our results suggest that non-jetted x-ray tdes likely originate from partial disruptions and/or disruptions of low-mass stars. | new physical insights about tidal disruption events from a comprehensive observational inventory at x-ray wavelengths |
jwst is providing the unique opportunity to directly study feedback processes regulating star formation (sf) in early galaxies. the two $z>5$ quiescent systems (jades-gs-z7-01-qu and macs0417-z5bbg) detected so far show a recent starburst after which sf is suppressed. to clarify whether such quenching is due to supernova (sn) feedback, we have developed a minimal physical model. we derive a condition on the minimum star formation rate, $\rm sfr_{min}$, lasting for a time interval $\delta t_{b}$, required to quench sf in a galaxy at redshift $z$, with gas metallicity $z$, and hosted by a halo of mass $m_h$. we find that lower $(z, z, m_h)$ systems are more easily quenched. we then apply the condition to jades-gs-z7-01-qu ($z=7.3$, $m_\star=10^{8.6} m_\odot$) and macs0417-z5bbg ($z=5.2$, $m_\star=10^{7.6} m_\odot$), and find that sn feedback largely fails to reproduce the observed quenched sf history. alternatively, we suggest that sf is rapidly suppressed by radiation-driven dusty outflows sustained by the high specific sfr (43 and 25 gyr$^{-1}$, respectively) of the two galaxies. our model provides a simple tool to interpret the sf histories of post-starburst galaxies, and unravel quenching mechanisms from incoming jwst data. | can supernovae quench star formation in high-$z$ galaxies? |
the first detection of gravitational waves from a neutron star-neutron star (ns-ns) merger, gw170817, and the increasing number of observations of short gamma-ray bursts have greatly motivated studies of the origins of ns-ns and neutron star-black hole (ns-bh) binaries. we calculate the merger rates of ns-ns and ns-bh binaries from globular clusters (gcs) using realistic gc simulations with the cmc cluster catalog. we use a large sample of models with a range of initial numbers of stars, metallicities, virial radii, and galactocentric distances, representative of the present-day milky way gcs, to quantify the inspiral times and volumetric merger rates as a function of redshift, both inside and ejected from clusters. we find that over the complete lifetime of most gcs, stellar bhs dominate the cluster cores and prevent the mass segregation of nss, thereby reducing the dynamical interaction rates of nss so that at most a few ns binary mergers are ever produced. we estimate the merger rate in the local universe to be ∼0.02 gpc-3 yr-1 for both ns-ns and ns-bh binaries, or a total of ∼0.04 gpc-3 yr-1 for both populations. these rates are about 5 orders of magnitude below the current empirical merger rate from the laser interferometer gravitational-wave observatory/virgo. we conclude that dynamical interactions in gcs do not play a significant role in enhancing the ns-ns and ns-bh merger rates. | on the rate of neutron star binary mergers from globular clusters |
the merger rate of stellar-mass black hole binaries (sbhbs) inferred by the advanced laser interferometer gravitational-wave observatory (ligo) suggests the need for an efficient source of sbhb formation. active galactic nucleus (agn) disks are a promising location for the formation of these sbhbs, as well as binaries of other compact objects, because of powerful torques exerted by the gas disk. these gas torques cause orbiting compact objects to migrate toward regions in the disk where inward and outward torques cancel, known as migration traps. we simulate the migration of stellar mass black holes in an example of a model agn disk, using an augmented n-body code that includes analytic approximations to migration torques, stochastic gravitational forces exerted by turbulent density fluctuations in the disk, and inclination and eccentricity dampening produced by passages through the gas disk, in addition to the standard gravitational forces between objects. we find that sbhbs form rapidly in our model disk as stellar-mass black holes migrate toward the migration trap. these sbhbs are likely to subsequently merge on short timescales. the process continues, leading to the build-up of a population of over-massive stellar-mass black holes. the formation of sbhbs in agn disks could contribute significantly to the sbhb merger rate inferred by ligo. | orbital migration of interacting stellar mass black holes in disks around supermassive black holes |
we present chandra and very large array observations of gw170817 at ∼521-743 days post-merger, and a homogeneous analysis of the entire chandra data set. we find that the late-time nonthermal emission follows the expected evolution of an off-axis relativistic jet, with a steep temporal decay {f}ν \propto {t}-1.95+/- 0.15 and power-law spectrum {f}ν \propto {ν }-0.575+/- 0.007. we present a new method to constrain the merger environment density based on diffuse x-ray emission from hot plasma in the host galaxy and find n≤slant 9.6× {10}-3 {cm}}-3. this measurement is independent from inferences based on jet afterglow modeling and allows us to partially solve for model degeneracies. the updated best-fitting model parameters with this density constraint are a fireball kinetic energy {e}0={1.5}-1.1+3.6× {10}49 {erg} ({e}iso}={2.1}-1.5+6.4× {10}52 {erg}) and jet opening angle {θ }0={5.9}-0.7+1.0 \deg with characteristic lorentz factor {{{γ }}}j={163}-43+23, expanding in a low-density medium with {n}0={2.5}-1.9+4.1× {10}-3 {cm}}-3 and viewed {θ }obs}={30.4}-3.4+4.0 \deg off-axis. the synchrotron emission originates from a power-law distribution of electrons with index p={2.15}-0.02+0.01. the shock microphysics parameters are constrained to {ɛ }{{e}}={0.18}-0.13+0.30 and {ɛ }{{b}}={2.3}-2.2+16.0× {10}-3. furthermore, we investigate the presence of x-ray flares and find no statistically significant evidence of ≥2.5σ of temporal variability at any time. finally, we use our observations to constrain the properties of synchrotron emission from the deceleration of the fastest kilonova ejecta with energy {e}kkn}\propto {({{γ }}β )}-αinto the environment, finding that shallow stratification indexes α ≤ 6 are disfavored. future radio and x-ray observations will refine our inferences on the fastest kilonova ejecta properties. | two years of nonthermal emission from the binary neutron star merger gw170817: rapid fading of the jet afterglow and first constraints on the kilonova fastest ejecta |
the overabundance of super-early (redshift $z>10$), luminous ($m_{\rm uv} < -20$), and blue galaxies detected by jwst has been explained (ferrara et al. 2023) as due to negligible dust attenuation in these systems. we show that such model correctly reproduces the uv luminosity function at $z>10$, and the star formation rate (sfr) density evolution. the model also predicts, in agreement with data, that the cosmic specific sfr grows as ${\rm ssfr} \propto (1+z)^{3/2}$. at $z \simeq 10$ the cosmic ssfr crosses the critical value $\rm ssfr^\star = 25\, \rm gyr^{-1}$ and $\approx 45$% of the galaxies become super-eddington driving outflows reaching velocities of $\approx 830 \,(\epsilon_\star/f_m)^{1/2}\, {\rm km\, s}^{-1}$, where $\epsilon_\star$ and $f_m$ are the sf efficiency and fraction of the halo gas expelled in the outflow, respectively. this prediction is consistent with the outflow velocities measured in 12 super-eddington galaxies of the jwst/jades sample. such outflows clear the dust, thus boosting the galaxy luminosity. they also dramatically enhance the visibility of the ly$\alpha$ line from $z>10$ galaxies, by introducing a velocity offset. the observed ly$\alpha$ properties in gn-z11 ($z=10.6$) are simultaneously recovered by the outflow model if $\log n_{\rm hi} \simeq 20.1$, implying that the outflow is largely ionized. we make analogous predictions for the ly$\alpha$ visibility of other super-early galaxies, and compare the model with ly$\alpha$ surveys at $z>7$, finding that essentially all super-eddington (sub-eddington) galaxies are (not) detected in ly$\alpha$. finally, the ssfr positively correlates with the lyc escape fraction as outflows carve ionized, transparent channels through which lyc photons leak. | super-early jwst galaxies, outflows and lyman alpha visibility in the eor |
a key outstanding question in star and planet formation is how far the initial mass function of stars and sub-stellar objects extends, and whether or not there is a cut-off at the very lowest masses. isolated objects in the planetary-mass domain below 13 jupiter masses, where not even deuterium can fuse, are very challenging to observe as these objects are inherently faint. nearby star-forming regions provide the best opportunity to search for them though: while they are young, they are still relatively warm and luminous at infrared wavelengths. previous surveys have discovered a handful of such sources down to 3--5 jupiter masses, around the minimum mass limit established for formation via the fragmentation of molecular clouds, but does the mass function extend further? in a new james webb space telescope near-infrared survey of the inner orion nebula and trapezium cluster, we have discovered and characterised a sample of 540 planetary-mass candidates with masses down to 0.6 jupiter masses, demonstrating that there is indeed no sharp cut-off in the mass function. furthermore, we find that 9\% of the planetary-mass objects are in wide binaries, a result that is highly unexpected and which challenges current theories of both star and planet formation. | jupiter mass binary objects in the trapezium cluster |
we still do not understand how planets form or why extrasolar planetary systems are so different from our own solar system. however, the past few years have dramatically changed our view of the disks of gas and dust around young stars. observations with the atacama large millimeter/submillimeter array and extreme adaptive-optics systems have revealed that most—if not all—disks contain substructure, including rings and gaps1-3, spirals4-6, azimuthal dust concentrations7 and shadows cast by misaligned inner disks5,8. these features have been interpreted as signatures of newborn protoplanets, but the exact origin is unknown. here we report the kinematic detection of a few-jupiter-mass planet located in a gas and dust gap at 130 au in the disk surrounding the young star hd 97048. an embedded planet can explain both the disturbed keplerian flow of the gas, detected in co lines, and the gap detected in the dust disk at the same radius. while gaps appear to be a common feature in protoplanetary disks2,3, we present a direct correspondence between a planet and a dust gap, indicating that at least some gaps are the result of planet-disk interactions. | kinematic detection of a planet carving a gap in a protoplanetary disk |
we study the gravitational wave (gw) signal from eight new 3d core-collapse supernova simulations. we show that the signal is dominated by f- and g-mode oscillations of the protoneutron star (pns) and its frequency evolution encodes the contraction rate of the latter, which, in turn, is known to depend on the star’s mass, on the equation of state, and on transport properties in warm nuclear matter. a lower-frequency component of the signal, associated with the standing accretion shock instability, is found in only one of our models. finally, we show that the energy radiated in gws is proportional to the amount of turbulent energy accreted by the pns. | characterizing the gravitational wave signal from core-collapse supernovae |
in ligo’s o1 and o2 observational runs, the detectors were sensitive to stellar-mass binary black hole (bbh) coalescences with component masses up to 100 {m}⊙ , with binaries with primary masses above 40 {m}⊙representing ≳90% of the total accessible sensitive volume. nonetheless, of the 5.9 detections (gw150914, lvt151012, gw151226, gw170104, gw170608, and gw170814) reported by ligo-virgo, the most massive binary detected was gw150914 with a primary component mass of ∼ 36 {m}⊙ , far below the detection mass limit. furthermore, there are theoretical arguments in favor of an upper mass gap, predicting an absence of black holes in the mass range 50≲ m≲ 135 {m}⊙ . we argue that the absence of detected binary systems with component masses heavier than ∼ 40 {m}⊙may be preliminary evidence for this upper mass gap. by allowing for the presence of a mass gap, we find weaker constraints on the shape of the underlying mass distribution of bbhs. we fit a power-law distribution with an upper mass cutoff to real and simulated bbh mass measurements, finding that the first 3.9 bbhs favor shallow power-law slopes α ≲ 3 and an upper mass cutoff {m}\max ∼ 40 {m}⊙ . this inferred distribution is entirely consistent with the two recently reported detections, gw170608 and gw170814. we show that with ∼10 additional ligo-virgo bbh detections, fitting the bh mass distribution will provide strong evidence for an upper mass gap if one exists. | where are ligo’s big black holes? |
we present results of the largest, most comprehensive study ever done of the stellar multiplicity of the most common stars in the galaxy, the red dwarfs. we have conducted an all-sky volume-limited survey for stellar companions to 1120 m dwarf primaries known to lie within 25 pc of the sun via trigonometric parallaxes. in addition to a comprehensive literature search, stars were explored in new surveys for companions at separations of 2″-300″. a reconnaissance of wide companions to separations of 300″ was done via blinking archival images. i-band images were used to search our sample for companions at separations of 2″-180″. various astrometric and photometric methods were used to probe the inner 2″ to reveal close companions. we report the discovery of 20 new companions and identify 56 candidate multiple systems. we find a stellar multiplicity rate of 26.8 ± 1.4% and a stellar companion rate of 32.4 ± 1.4% for m dwarfs. there is a broad peak in the separation distribution of the companions at 4-20 au, with a weak trend of smaller projected linear separations for lower mass primaries. a hint that m-dwarf multiplicity may be a function of tangential velocity is found, with faster moving, presumably older, stars found to be multiple somewhat less often. we calculate that stellar companions make up at least 17% of mass attributed to m dwarfs in the solar neighborhood, with roughly 11% of m-dwarf mass hidden as unresolved companions. finally, when considering all m-dwarf primaries and companions, we find that the mass distribution for m dwarfs increases to the end of the stellar main sequence. | the solar neighborhood. xlv. the stellar multiplicity rate of m dwarfs within 25 pc |
we utilise multi-epoch muse spectroscopy to study binary stars in the core of the galactic globular cluster ngc 3201. our sample consists of 3553 stars with 54 883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity measurements within five years of observations. we introduce a statistical method to determine the probability of a star showing radial velocity variations based on the whole inhomogeneous radial velocity sample. using hst photometry and an advanced dynamical mocca simulation of this specific cluster we overcome observational biases that previous spectroscopic studies had to deal with. this allows us to infer a binary frequency in the muse field of view and enables us to deduce the underlying true binary frequency of (6.75 ± 0.72)% in ngc 3201. the comparison of the muse observations with the mocca simulation suggests a large portion of primordial binaries. we can also confirm a radial increase in the binary fraction towards the cluster centre due to mass segregation. we discovered that in the core of ngc 3201 at least (57.5 ± 7.9)% of blue straggler stars are in a binary system. for the first time in a study of globular clusters, we were able to fit keplerian orbits to a significant sample of 95 binaries. we present the binary system properties of eleven blue straggler stars and the connection to sx phoenicis-type stars. we show evidence that two blue straggler formation scenarios, the mass transfer in binary (or triple) star systems and the coalescence due to binary-binary interactions, are present in our data. we also describe the binary and spectroscopic properties of four sub-subgiant (or red straggler) stars. furthermore, we discovered two new black hole candidates with minimum masses (m sin i) of (7.68 ± 0.50) m⊙, (4.4 ± 2.8) m⊙, and refine the minimum mass estimate on the already published black hole to (4.53 ± 0.21) m⊙. these black holes are consistent with an extensive black hole subsystem hosted by ngc 3201. the full radial velocity sample (table a.1) 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/cat/j/a+a/632/a3 | a stellar census in globular clusters with muse: binaries in ngc 3201 |
the ([α/fe], [fe/h]) distribution of milky way stars shows at least two distinct sequences, which have traditionally been associated with the thin and thick disc components. the abundance distribution varies systematically with location r and |z| across the galaxy. we reproduce this using an analytical chemodynamical model that includes the effects of radial migration and kinematic heating. unlike some earlier models, our scheme does not require a distinct thick disc component emerging from a separate evolutionary path. the proposed model has a continuous star formation history and a continuous age velocity dispersion relation. moreover, [α/fe] is constant for stellar ages less than 8 gyr, but increases sharply for older stars over a time-scale of 1.5 gyr. the gap between the two sequences is due to this sharp transition. we show that the high-[α/fe] sequence at the low-metallicity end is simply a pile-up of old stars, but towards the high-metallicity end, the age progressively decreases and stars have small birth radii. our model successfully explains the uniformity of the locus of the high-[α/fe] sequence across different locations. the low-[α/fe] sequence contains stars with different birth radii that owes its existence to radial migration. for the low-[α/fe] stars, angular momentum is anticorrelated with [fe/h], while the opposite is true for high-[α/fe] stars. we show that the later trend can be explained by the increase of circular velocity with time. if radial migration is not included, the model fails to generate the double sequence and instead shows only a single sequence. our simple scheme has major advantages over earlier chemodynamical models, as we show. | chemical enrichment and radial migration in the galactic disc - the origin of the [αfe] double sequence |
the final phase of the reionization process can be probed by rest-frame uv absorption spectra of quasars at z ≳ 6, shedding light on the properties of the diffuse intergalactic medium within the first gyr of the universe. the eso large programme 'xqr-30: the ultimate xshooter legacy survey of quasars at z ≃ 5.8-6.6' dedicated ~250 h of observations at the vlt to create a homogeneous and high-quality sample of spectra of 30 luminous quasars at z ~ 6, covering the rest wavelength range from the lyman limit to beyond the mg ii emission. twelve quasar spectra of similar quality from the xshooter archive were added to form the enlarged xqr-30 sample, corresponding to a total of ~350 h of on-source exposure time. the median effective resolving power of the 42 spectra is r ≃ 11 400 and 9800 in the vis and nir arm, respectively. the signal-to-noise ratio per 10 km s-1 pixel ranges from ~11 to 114 at λ ≃ 1285 å rest frame, with a median value of ~29. we describe the observations, data reduction, and analysis of the spectra, together with some first results based on the e-xqr-30 sample. new photometry in the h and k bands are provided for the xqr-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the sample. the composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first gyr of the universe. | xqr-30: the ultimate xshooter quasar sample at the reionization epoch |
the visibility of high-redshift lyman-alpha emitting galaxies (laes) provides important constraints on galaxy formation processes and the epoch of reionization (eor). however, predicting realistic and representative statistics for comparison with observations represents a significant challenge in the context of large-volume cosmological simulations. the thesan project offers a unique framework for addressing such limitations by combining state-of-the-art galaxy formation (illustristng) and dust models with the arepo-rt radiation-magnetohydrodynamics solver. in this initial study, we present lyman-alpha centric analysis for the flagship simulation that resolves atomic cooling haloes throughout a $(95.5\, \text{cmpc})^3$ region of the universe. to avoid numerical artefacts, we devise a novel method for accurate frequency-dependent line radiative transfer in the presence of continuous hubble flow, transferable to broader astrophysical applications as well. our scalable approach highlights the utility of laes and red damping-wing transmission as probes of reionization, which reveal nontrivial trends across different galaxies, sightlines, and frequency bands that can be modelled in the framework of covering fractions. in fact, after accounting for environmental factors influencing large-scale ionized bubble formation such as redshift and uv magnitude, the variation across galaxies and sightlines mainly depends on random processes including peculiar velocities and self-shielded systems that strongly impact unfortunate rays more than others. throughout the eor local and cosmological optical depths are often greater than or less than unity such that the exp (- τ) behaviour leads to anisotropic and bimodal transmissivity. future surveys will benefit by targeting both rare bright objects and goldilocks zone laes to infer the presence of these (un)predictable (dis)advantages. | the thesan project: lyman-α emission and transmission during the epoch of reionization |
e-astrogam (`enhanced astrogam') is a breakthrough observatory space mission, with a detector composed by a silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal universe in the photon energy range from 0.3 mev to 3 gev - the lower energy limit can be pushed to energies as low as 150 kev, albeit with rapidly degrading angular resolution, for the tracker, and to 30 kev for calorimetric detection. the mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. thanks to its performance in the mev-gev domain, substantially improving its predecessors, e-astrogam will open a new window on the non-thermal universe, making pioneering observations of the most powerful galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. with a line sensitivity in the mev energy range one to two orders of magnitude better than previous generation instruments, e-astrogam will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our galaxy. the mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as ligo-virgo-geo600-kagra, ska, alma, e-elt, tmt, lsst, jwst, athena, cta, icecube, km3net, and the promise of elisa. | the e-astrogam mission. exploring the extreme universe with gamma rays in the mev - gev range |
the past decades have witnessed a lot of progress in gravitational lensing with two main targets: stars and galaxies (with active galactic nuclei). the success is partially attributed to the continuous luminescence of these sources making the detection and monitoring relatively easy. with the running of ongoing and upcoming large facilities/surveys in various electromagnetic and gravitational-wave bands, the era of time-domain surveys would guarantee constant detection of strongly lensed explosive transient events, for example, supernovae in all types, gamma ray bursts with afterglows in all bands, fast radio bursts, and even gravitational waves. lensed transients have many advantages over the traditional targets in studying the universe, and magnification effect helps to understand the transients themselves at high redshifts. in this review article, on base of the recent achievements in literature, we summarize the methods of searching for different kinds of lensed transient signals, the latest results on detection and their applications in fundamental physics, astrophysics, and cosmology. at the same time, we give supplementary comments as well as prospects of this emerging research direction that may help readers who are interested in entering this field. | strongly lensed transient sources: a review |
tidal disruption events (tdes) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close1. tdes provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet2-9, but the necessary conditions are not fully understood. the best-studied jetted tde so far is swift j1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. here we report the optical detection of at2022cmc, a rapidly fading source at cosmological distance (redshift z = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. observations of a bright counterpart at other wavelengths, including x-ray, submillimetre and radio, supports the interpretation of at2022cmc as a jetted tde containing a synchrotron `afterglow', probably launched by a supermassive black hole with spin greater than approximately 0.3. using four years of zwicky transient facility10 survey data, we calculate a rate of 0.0 2−0.01+0.04 gpc−3 yr−1 for on-axis jetted tdes on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from x-ray and radio observations11. correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of tdes have relativistic jets. optical surveys can use at2022cmc as a prototype to unveil a population of jetted tdes. | a very luminous jet from the disruption of a star by a massive black hole |
in this paper we study the possibility of having a wormhole (wh) as a candidate for the sgr a⋆ central object and test this idea by constraining their geometry using the motion of s2 star and the reconstructed shadow images. in particular, we consider three wh models, including whs in einstein theory, brane-world gravity, and einstein-dirac-maxwell theory. to this end, we have constrained the wh throat using the motion of s2 star and shown that the flare out condition is satisfied. we also consider the accretion of infalling gas model and study the accretion rate and the intensity of the electromagnetic radiation as well as the shadow images. | constraining wormhole geometries using the orbit of s2 star and the event horizon telescope |
the polarization of fast radio bursts (frbs), which are bright astronomical transient phenomena, contains information about their environments. using wide-band observations with two telescopes, we report polarization measurements of five repeating frbs and find a trend of lower polarization at lower frequencies. this behavior is modeled as multipath scattering, characterized by a single parameter, σrm, the rotation measure (rm) scatter. sources with higher σrm have higher rm magnitude and scattering time scales. the two sources with the highest σrm, frb 20121102a and frb 20190520b, are associated with compact persistent radio sources. these properties indicate a complex environment near the repeating frbs, such as a supernova remnant or a pulsar wind nebula, consistent with their having arisen from young stellar populations. | frequency-dependent polarization of repeating fast radio bursts—implications for their origin |
planets orbiting m-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. the small size of m dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. however, it remains unknown whether their host stars' highly variable extreme-uv radiation environments allow atmospheres to persist. with jwst, we have begun to determine whether or not the most favorable rocky worlds orbiting m dwarfs have detectable atmospheres. here, we present a 2.8-5.2 μm jwst nirspec/g395h transmission spectrum of the warm (700 k, 40.3× earth's insolation) super-earth gj 486b (1.3 r ⊕ and 3.0 m ⊕). the measured spectrum from our two transits of gj 486b deviates from a flat line at 2.2σ - 3.3σ, based on three independent reductions. through a combination of forward and retrieval models, we determine that gj 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of h2o > 10% to 2σ) or the transmission spectrum is contaminated by water present in cool unocculted starspots. we also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. while both retrieval scenarios provide equal quality fits ( ${\chi }_{\nu }^{2}=1.0$ ) to our nirspec/g395h observations, shorter wavelength observations can break this degeneracy and reveal if gj 486b sustains a water-rich atmosphere. | high tide or riptide on the cosmic shoreline? a water-rich atmosphere or stellar contamination for the warm super-earth gj 486b from jwst observations |
the r-process nucleosynthesis in core-collapse supernovae (cc-sne) is studied, with a focus on the explosion scenario induced by rotation and strong magnetic fields. nucleosynthesis calculations are conducted based on magneto-hydrodynamical explosion models with a wide range of parameters for initial rotation and magnetic fields. the explosion models are classified in two different types: prompt-magnetic-jet and delayed-magnetic-jet, for which the magnetic fields of proto-neutron stars (pnss) during collapse and the core-bounce are strong and comparatively moderate, respectively. following the hydrodynamical trajectories of each explosion model, we confirmed that r-processes successfully occur in the prompt-magnetic-jets, which produce heavy nuclei including actinides. on the other hand, the r-process in the delayed-magnetic-jet is suppressed, which synthesizes only nuclei up to the second peak (a∼ 130). thus, the r-process in the delayed-magnetic-jets could explain only “weak r-process” patterns observed in metal-poor stars rather than the “main r-process,” represented by the solar abundances. our results imply that cc-sne are possible astronomical sources of heavy r-process elements if their magnetic fields are strong enough, while weaker magnetic explosions may produce “weak r-process” patterns (a≲ 130). we show the potential importance and necessity of magneto-rotational sne for explaining the galactic chemical evolution, as well as abundances of r-process enhanced metal-poor stars. we also examine the effects of the remaining uncertainties in the nature of pnss due to weak interactions that determine the final neutron-richness of ejecta. additionally, we briefly discuss radioactive isotope yields in primary jets (e.g., 56ni), with relation to several optical observation of sne and relevant high-energy astronomical phenomena. | the r-process nucleosynthesis in the various jet-like explosions of magnetorotational core-collapse supernovae |
feedback from supermassive black holes (smbhs) is believed to be a critical driver of the observed quenching of star formation and color bimodality of galaxies above the milky way mass scale. in recent years, various forms of smbh feedback have been implemented as subgrid models in galaxy formation simulations, but most implementations have involved simplified prescriptions or coarse-grained models of the interstellar medium (ism). we present the first set of fire-3 cosmological zoom-in simulations with agn feedback evolved to $z\sim0$, examining a set of galaxies with halos in the mass range $10^{12}-10^{13}\,{\rm m_{\odot}}$. these high-resolution simulations combine detailed stellar and ism physics with multi-channel agn feedback including radiative feedback, mechanical outflows, and in some simulations, cosmic rays. we find that massive (>l*) galaxies in these simulations can match local scaling relations including the stellar mass-halo mass relation, the $m_{\rm bh}$-$\sigma$ relation, the size-mass relation, and the faber-jackson relation. many of the massive galaxies in the simulations with agn feedback have quenched star formation and elliptical morphologies, in qualitative agreement with observations. in contrast, simulations at the massive end without agn feedback produce galaxies that are too massive and form stars at too high rates, are order-of-magnitude too compact, and have velocity dispersions well above faber-jackson. despite these successes, the agn physics models analyzed do not necessarily produce uniformly realistic galaxies across the full mass range studied when the feedback parameters are held constant, indicating that further refinements of the black hole modeling may be warranted. | formation of quenched massive galaxies in fire cosmological zoom-in simulations with multi-channel agn feedback |
abridged - stars with zams masses between 140 and $260 m_\odot$ are thought to explode as pair-instability supernovae (pisne). during their thermonuclear runaway, pisne can produce up to several tens of solar masses of radioactive nickel, resulting in luminous transients similar to some superluminous supernovae (slsne). yet, no unambiguous pisn has been discovered so far. sn2018ibb is a h-poor slsn at $z=0.166$ that evolves extremely slowly compared to the hundreds of known slsne. between mid 2018 and early 2022, we monitored its photometric and spectroscopic evolution from the uv to the nir with 2-10m class telescopes. sn2018ibb radiated $>3\times10^{51} \rm erg$ during its evolution, and its bolometric light curve reached $>2\times10^{44} \rm erg\,s^{-1}$ at peak. the long-lasting rise of $>93$ rest-frame days implies a long diffusion time, which requires a very high total ejected mass. the pisn mechanism naturally provides both the energy source ($^{56}$ni) and the long diffusion time. theoretical models of pisne make clear predictions for their photometric and spectroscopic properties. sn2018ibb complies with most tests on the light curves, nebular spectra and host galaxy, potentially all tests with the interpretation we propose. both the light curve and the spectra require 25-44 $m_\odot$ of freshly nucleosynthesised $^{56}$ni, pointing to the explosion of a metal-poor star with a he-core mass of 120-130 $m_\odot$ at the time of death. this interpretation is also supported by the tentative detection of [co ii]$\lambda$1.025$\mu$m, which has never been observed in any other pisn candidate or slsn before. powering by a central engine, such as a magnetar or a black hole, can be excluded with high confidence. this makes sn2018ibb by far the best candidate for being a pisn, to date. | 1100 days in the life of the supernova 2018ibb -- the best pair-instability supernova candidate, to date |
here we review present knowledge of the long-term behaviour of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. the concept of solar activity is discussed along with an overview of the dedicated indices used to quantify different aspects of variable solar activity, with special emphasis on sunspot numbers. over long timescales, quantitative information about past solar activity is historically obtained using a method based on indirect proxies, such as cosmogenic isotopes 14c and 10be in natural stratified archives (e.g., tree rings or ice cores). we give a historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state of the art. special attention is paid to the verification and cross-calibration of reconstructions. it is argued that the method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to millennia) during the holocene (the past ∼12 millennia). a separate section is devoted to reconstructions of extremely rare solar eruptive events in the past, based on both cosmogenic-proxy data in terrestrial and lunar natural archives, as well as statistics of sun-like stars. finally, the main features of the long-term evolution of solar magnetic activity, including the statistics of grand minima and maxima occurrence, are summarized and their possible implications, especially for solar/stellar dynamo theory, are discussed. | a history of solar activity over millennia |
we present possis, a time-dependent three-dimensional monte carlo code for modelling radiation transport in supernovae and kilonovae. the code incorporates wavelength- and time-dependent opacities, and predicts viewing-angle dependent spectra, light curves, and polarization for both idealized and hydrodynamical explosion models. we apply the code to a kilonova model with two distinct ejecta components, one including lanthanide elements with relatively high opacities and the other devoid of lanthanides and characterized by lower opacities. we find that a model with total ejecta mass m_ej=0.04 m_⊙ and half-opening angle of the lanthanide-rich component φ = 30° provides a good match to gw 170817/at 2017gfo for orientations near the polar axis (i.e. for a system viewed close to face-on). we then show how crucial is the use of self-consistent multidimensional models in place of combining one-dimensional models to infer important parameters, such as the ejecta masses. we finally explore the impact of mej and φ on the synthetic observables and highlight how the relatively fast computation times of possis make it well-suited to perform parameter-space studies and extract key properties of supernovae and kilonovae. spectra calculated with possis in this and future studies will be made publicly available. | possis: predicting spectra, light curves, and polarization for multidimensional models of supernovae and kilonovae |
we illustrate the formation and evolution of the milky way over cosmic time, utilizing a sample of 10 million red giant stars with full chemodynamical information, including metallicities and $\alpha$-abundances from low-resolution gaia xp spectra. the evolution of angular momentum as a function of metallicity - a rough proxy for stellar age, particularly for high-[$\alpha$/fe] stars - displays three distinct phases: the disordered and chaotic protogalaxy, the kinematically-hot old disk, and the kinematically-cold young disk. the old high-$\alpha$ disk starts at [fe/h] $\approx -1.0$, 'spinning up' from the nascent protogalaxy, and then exhibits a smooth 'cooldown' toward more ordered and circular orbits at higher metallicities. the young low-$\alpha$ disk is kinematically cold throughout its metallicity range, with its observed properties modulated by a strong radial gradient. we interpret these trends using milky way analogs from the tng50 cosmological simulation, identifying one that closely matches the kinematic evolution of our galaxy. this halo's protogalaxy spins up into a relatively thin and misaligned high-$\alpha$ disk at early times, which is subsequently heated and torqued by a major gas-rich merger. the merger contributes a large amount of low-metallicity gas and angular momentum, from which the kinematically cold low-$\alpha$ stellar disk is subsequently born. this simulated history parallels several observed features of the milky way, particularly the decisive 'gse' merger that likely occurred at $z \approx 2$. our results provide an all-sky perspective on the emerging picture of our galaxy's three-phase formation, impelled by the three physical mechanisms of spinup, merger, and cooldown. | the three-phase evolution of the milky way |
observed accretion rates onto the milky-way and other local spirals fall short of that required to sustain star formation for cosmological timescales. a potential avenue for this unseen accretion is an inflow in the volume-filling hot phase ($\sim10^6$ k) of the circumgalactic medium (cgm), as suggested by some cosmological simulations. we derive an approximate axisymmetric analytic solution of such hot cgm accretion flows, and validate it with hydrodynamic simulations. we show that a hot inflow spins up as it approaches the galaxy, while remaining hot, subsonic and quasi-spherical. at the radius of angular momentum support ($\approx15$ kpc for the milky-way) the hot flow flattens into a disk geometry and then cools from $\sim10^6$ k to $\sim10^4$ k at the disk-halo interface. cooling affects all hot gas, rather than just a subset of individual gas clouds, implying that accretion via hot inflows does not rely on local thermal instability in contrast with 'precipitation' models for galaxy accretion. prior to cooling and accretion the inflow completes $\sim t_{\rm cool}/t_{\rm ff}$ radians of rotation, where $t_{\rm cool}/t_{\rm ff}$ is the cooling time to free-fall time ratio in hot gas immediately outside the galaxy. the ratio $t_{\rm cool}/t_{\rm ff}$ may thus govern the development of turbulence and enhancement of magnetic fields in gas accreting onto low-redshift spirals. we argue that accretion via hot inflows can explain the observed truncation of nearby thin stellar disks at $\approx4$ disk radii. we also show that if rotating hot inflows are common in milky-way size disk galaxies, as predicted, then signatures should be observable with x-ray telescopes, kinetic sz measurements, and frb surveys. | accretion onto disk galaxies via hot and rotating cgm inflows |
context. how galaxies form, assemble, and cease their star formation is a central question within the modern landscape of galaxy evolution studies. these processes are indelibly imprinted on the galaxy stellar mass function (smf), and its measurement and understanding is key to uncovering a unified theory of galaxy evolution.aims: we present constraints on the shape and evolution of the galaxy smf, the quiescent galaxy fraction, and the cosmic stellar mass density across 90% of the history of the universe from z = 7.5 → 0.2 as a means to study the physical processes that underpin galaxy evolution.methods: the cosmos survey is an ideal laboratory for studying representative galaxy samples. now equipped with deeper and more homogeneous near-infrared coverage exploited by the cosmos2020 catalog, we leverage the large 1.27 deg2 effective area to improve sample statistics and understand spatial variations (cosmic variance) - particularly for rare, massive galaxies - and push to higher redshifts with greater confidence and mass completeness than previous studies. we divide the total stellar mass function into star-forming and quiescent subsamples through nuvrj color-color selection. the measurements are then fit with single- and double-component schechter functions to infer the intrinsic galaxy stellar mass function, the evolution of its key parameters, and the cosmic stellar mass density out to z = 7.5. finally, we compare our measurements to predictions from state-of-the-art cosmological simulations and theoretical dark matter halo mass functions.results: we find a smooth, monotonic evolution in the galaxy stellar mass function since z = 7.5, in general agreement with previous studies. the number density of star-forming systems have undergone remarkably consistent growth spanning four decades in stellar mass from z = 7.5 → 2 whereupon high-mass systems become predominantly quiescent ("downsizing"). meanwhile, the assembly and growth of low-mass quiescent systems only occurred recently, and rapidly. an excess of massive systems at z ≈ 2.5 − 5.5 with strikingly red colors, with some being newly identified, increase the observed number densities to the point where the smf cannot be reconciled with a schechter function.conclusions: systematics including cosmic variance and/or active galactic nuclei contamination are unlikely to fully explain this excess, and so we speculate that they may be dust-obscured populations similar to those found in far infrared surveys. furthermore, we find a sustained agreement from z ≈ 3 − 6 between the stellar and dark matter halo mass functions for the most massive systems, suggesting that star formation in massive halos may be more efficient at early times. data files containing sample ids and key measurements are available for download: https://doi.org/10.5281/zenodo.7808832 | cosmos2020: the galaxy stellar mass function. the assembly and star formation cessation of galaxies at 0.2< z ≤ 7.5 |
in this work we study the properties of compact spheres made of a charged perfect fluid with a mit bag model eos for quark matter. considering static spherically symmetric spacetime we derive the hydrostatic equilibrium equations in the recently formulated four dimensional einstein-gauss-bonnet (4d egb) gravity theory. in this setting, the modified tov equations are solved numerically with the aim to investigate the impact of electric charge on the stellar structure. a nice feature of 4d egb theory is that the gauss-bonnet term has a non-vanishing contribution to the gravitational dynamics in 4d spacetime. we therefore analyse the effects of gauss-bonnet coupling constant α and the charge fraction β on the mass-radius (m -r ) diagram and also the mass-central density (m -ρc) relation of quark stars. finally, we conclude that depending on the choice of coupling constant one could have larger mass and radius compared with gr and can also be relevant for more massive compact objects due to the effect of the repulsive coulomb force. | electrically charged quark stars in 4d einstein-gauss-bonnet gravity |
the laser interferometer space antenna1, lisa, will detect gravitational wave signals from extreme mass-ratio inspirals2, where a stellar mass compact object orbits a supermassive black hole and eventually plunges into it. here we report on lisa's capability to detect whether the smaller compact object in an extreme mass-ratio inspiral is endowed with a scalar field3,4, and to measure its scalar charge—a dimensionless quantity that acts as a measure of how much scalar field the object carries. by direct comparison of signals, we show that lisa will be able to detect and measure the scalar charge with an accuracy of the order of per cent, which is an unprecedented level of precision. this result is independent of the origin of the scalar field and of the structure and other properties of the small compact object, so it can be seen as a generic assessment of lisa's capabilities to detect new fundamental fields. | detecting fundamental fields with lisa observations of gravitational waves from extreme mass-ratio inspirals |
we present the atlas discovery and initial analysis of the first 18 days of the unusual transient event, atlas18qqn/at2018cow. it is characterized by a high peak luminosity (∼1.7 × 1044 erg s-1), rapidly evolving light curves (>5 mag rise to peak in ∼3.5 days), and hot blackbody spectra, peaking at ∼27,000 k that are relatively featureless and unchanging over the first two weeks. the bolometric light curve cannot be powered by radioactive decay under realistic assumptions. the detection of high-energy emission may suggest a central engine as the powering source. using a magnetar model, we estimated an ejected mass of 0.1-0.4 m {}⊙ , which lies between that of low-energy core-collapse events and the kilonova, at2017gfo. the spectra cooled rapidly from 27,000 to 15,000 k in just over two weeks but remained smooth and featureless. broad and shallow emission lines appear after about 20 days, and we tentatively identify them as he i although they would be redshifted from their rest wavelengths. we rule out that there are any features in the spectra due to intermediate mass elements up to and including the fe group. the presence of r-process elements cannot be ruled out. if these lines are due to he, then we suggest a low-mass star with residual he as a potential progenitor. alternatively, models of magnetars formed in neutron star mergers, or accretion onto a central compact object, give plausible matches to the data. | the cow: discovery of a luminous, hot, and rapidly evolving transient |
electrostatic analyzers of different designs have been used since the earliest days of the space age, beginning with the very earliest solar-wind measurements made by mariner 2 en route to venus in 1962. the parker solar probe (psp) mission, nasa’s first dedicated mission to study the innermost reaches of the heliosphere, makes its thermal plasma measurements using a suite of instruments called the solar wind electrons, alphas, and protons (sweap) investigation. sweap’s electron psp analyzer (solar probe analyzer-electron (span-e)) instruments are a pair of top-hat electrostatic analyzers on psp that are capable of measuring the electron distribution function in the solar wind from 2 ev to 30 kev. for the first time, in situ measurements of thermal electrons provided by span-e will help reveal the heating and acceleration mechanisms driving the evolution of the solar wind at the points of acceleration and heating, closer than ever before to the sun. this paper details the design of the span-e sensors and their operation, data formats, and measurement caveats from psp’s first two close encounters with the sun. | the solar probe analyzers—electrons on the parker solar probe |
we use the results from the alma large program aspecs, the spectroscopic survey in the hubble ultra deep field (hudf), to constrain co luminosity functions of galaxies and the resulting redshift evolution of ρ(h2). the broad frequency range covered enables us to identify co emission lines of different rotational transitions in the hudf at z > 1. we find strong evidence that the co luminosity function evolves with redshift, with the knee of the co luminosity function decreasing in luminosity by an order of magnitude from ∼2 to the local universe. based on schechter fits, we estimate that our observations recover the majority (up to ∼90%, depending on the assumptions on the faint end) of the total cosmic co luminosity at z = 1.0-3.1. after correcting for co excitation, and adopting a galactic co-to-h2 conversion factor, we constrain the evolution of the cosmic molecular gas density ρ(h2): this cosmic gas density peaks at z ∼ 1.5 and drops by a factor of {6.5}-1.4+1.8 to the value measured locally. the observed evolution in ρ(h2), therefore, closely matches the evolution of the cosmic star formation rate density ρ sfr. we verify the robustness of our result with respect to assumptions on source inclusion and/or co excitation. as the cosmic star formation history can be expressed as the product of the star formation efficiency and the cosmic density of molecular gas, the similar evolution of ρ(h2) and ρ sfr leaves only little room for a significant evolution of the average star formation efficiency in galaxies since z ∼ 3 (85% of cosmic history). | the alma spectroscopic survey in the hudf: co luminosity functions and the molecular gas content of galaxies through cosmic history |
we calculate static and spherically symmetric solutions for the rastall modification of gravity to describe neutron stars (ns). the key feature of the rastall gravity is the nonconservation of the energy-momentum tensor proportionally to the space-time curvature. using realistic equations of state for the ns interior we place a conservative bound on the non-general relativity behavior of the rastall theory which should be ≲1 % level. this work presents the more stringent constraints on the deviations of general relativity caused by the rastall proposal. | neutron stars in rastall gravity |
we study the possibility that self-interacting bosonic dark matter forms star-like objects. we study both the case of attractive and repulsive self-interactions, and we focus particularly in the parameter phase space where self-interactions can solve well standing problems of the collisionless dark matter paradigm. we find the mass radius relations for these dark matter bosonic stars, their density profile as well as the maximum mass they can support. | boson stars from self-interacting dark matter |
we present cosmological parameter results from the final full-mission planck measurements of the cosmic microwave background (cmb) anisotropies, combining information from the temperature and polarization maps and the lensing reconstruction. compared to the 2015 results, improved measurements of large-scale polarization allow the reionization optical depth to be measured with higher precision, leading to significant gains in the precision of other correlated parameters. improved modelling of the small-scale polarization leads to more robust constraints on many parameters, with residual modelling uncertainties estimated to affect them only at the 0.5σ level. we find good consistency with the standard spatially-flat 6-parameter λcdm cosmology having a power-law spectrum of adiabatic scalar perturbations (denoted "base λcdm" in this paper), from polarization, temperature, and lensing, separately and in combination. a combined analysis gives dark matter density ωch2 = 0.120 ± 0.001, baryon density ωbh2 = 0.0224 ± 0.0001, scalar spectral index ns = 0.965 ± 0.004, and optical depth τ = 0.054 ± 0.007 (in this abstract we quote 68% confidence regions on measured parameters and 95% on upper limits). the angular acoustic scale is measured to 0.03% precision, with 100θ* = 1.0411 ± 0.0003. these results are only weakly dependent on the cosmological model and remain stable, with somewhat increased errors, in many commonly considered extensions. assuming the base-λcdm cosmology, the inferred (model-dependent) late-universe parameters are: hubble constant h0 = (67.4 ± 0.5) km s-1 mpc-1; matter density parameter ωm = 0.315 ± 0.007; and matter fluctuation amplitude σ8 = 0.811 ± 0.006. we find no compelling evidence for extensions to the base-λcdm model. combining with baryon acoustic oscillation (bao) measurements (and considering single-parameter extensions) we constrain the effective extra relativistic degrees of freedom to be neff = 2.99 ± 0.17, in agreement with the standard model prediction neff = 3.046, and find that the neutrino mass is tightly constrained to ∑mν < 0.12 ev. the cmb spectra continue to prefer higher lensing amplitudes than predicted in base λcdm at over 2σ, which pulls some parameters that affect the lensing amplitude away from the λcdm model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) bao data. the joint constraint with bao measurements on spatial curvature is consistent with a flat universe, ωk = 0.001 ± 0.002. also combining with type ia supernovae (sne), the dark-energy equation of state parameter is measured to be w0 = -1.03 ± 0.03, consistent with a cosmological constant. we find no evidence for deviations from a purely power-law primordial spectrum, and combining with data from bao, bicep2, and keck array data, we place a limit on the tensor-to-scalar ratio r0.002 < 0.06. standard big-bang nucleosynthesis predictions for the helium and deuterium abundances for the base-λcdm cosmology are in excellent agreement with observations. the planck base-λcdm results are in good agreement with bao, sne, and some galaxy lensing observations, but in slight tension with the dark energy survey's combined-probe results including galaxy clustering (which prefers lower fluctuation amplitudes or matter density parameters), and in significant, 3.6σ, tension with local measurements of the hubble constant (which prefer a higher value). simple model extensions that can partially resolve these tensions are not favoured by the planck data. | planck 2018 results. vi. cosmological parameters |
this paper presents cosmological results based on full-mission planck observations of temperature and polarization anisotropies of the cosmic microwave background (cmb) radiation. our results are in very good agreement with the 2013 analysis of the planck nominal-mission temperature data, but with increased precision. the temperature and polarization power spectra are consistent with the standard spatially-flat 6-parameter λcdm cosmology with a power-law spectrum of adiabatic scalar perturbations (denoted "base λcdm" in this paper). from the planck temperature data combined with planck lensing, for this cosmology we find a hubble constant, h0 = (67.8 ± 0.9) km s-1mpc-1, a matter density parameter ωm = 0.308 ± 0.012, and a tilted scalar spectral index with ns = 0.968 ± 0.006, consistent with the 2013 analysis. note that in this abstract we quote 68% confidence limits on measured parameters and 95% upper limits on other parameters. we present the first results of polarization measurements with the low frequency instrument at large angular scales. combined with the planck temperature and lensing data, these measurements give a reionization optical depth of τ = 0.066 ± 0.016, corresponding to a reionization redshift of z_re=8.8+1.7-1.4. these results are consistent with those from wmap polarization measurements cleaned for dust emission using 353-ghz polarization maps from the high frequency instrument. we find no evidence for any departure from base λcdm in the neutrino sector of the theory; for example, combining planck observations with other astrophysical data we find neff = 3.15 ± 0.23 for the effective number of relativistic degrees of freedom, consistent with the value neff = 3.046 of the standard model of particle physics. the sum of neutrino masses is constrained to ∑ mν < 0.23 ev. the spatial curvature of our universe is found to be very close to zero, with | ωk | < 0.005. adding a tensor component as a single-parameter extension to base λcdm we find an upper limit on the tensor-to-scalar ratio of r0.002< 0.11, consistent with the planck 2013 results and consistent with the b-mode polarization constraints from a joint analysis of bicep2, keck array, and planck (bkp) data. adding the bkp b-mode data to our analysis leads to a tighter constraint of r0.002 < 0.09 and disfavours inflationarymodels with a v(φ) ∝ φ2 potential. the addition of planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. we find no evidence for any contribution from isocurvature perturbations or from cosmic defects. combining planck data with other astrophysical data, including type ia supernovae, the equation of state of dark energy is constrained to w = -1.006 ± 0.045, consistent with the expected value for a cosmological constant. the standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit planck base λcdm cosmology are in excellent agreement with observations. we also constraints on annihilating dark matter and on possible deviations from the standard recombination history. in neither case do we find no evidence for new physics. the planck results for base λcdm are in good agreement with baryon acoustic oscillation data and with the jla sample of type ia supernovae. however, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. we show that these tensions cannot easily be resolved with simple modifications of the base λcdm cosmology. apart from these tensions, the base λcdm cosmology provides an excellent description of the planck cmb observations and many other astrophysical data sets. | planck 2015 results. xiii. cosmological parameters |
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