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the detection of gravitational waves from mergers of tens of solar mass black hole binaries has led to a surge in interest in primordial black holes (pbhs) as a dark matter candidate. we aim to provide a (relatively) concise overview of the status of pbhs as a dark matter candidate, circa summer 2020. first we review the formation of pbhs in the early universe, focussing mainly on pbhs formed via the collapse of large density perturbations generated by inflation. then we review the various current and future constraints on the present day abundance of pbhs. we conclude with a discussion of the key open questions in this field. | primordial black holes as a dark matter candidate |
we describe the nirspec component of the jwst deep extragalactic survey (jades), and provide deep spectroscopy of 253 sources targeted with the nirspec micro-shutter assembly in the hubble ultra deep field and surrounding goods-south. the multi-object spectra presented here are the deepest so far obtained with jwst, amounting to up to 28 hours in the low-dispersion ($r\sim 30-300$) prism, and up to 7 hours in each of the three medium-resolution $r\approx 1000$ gratings and one high-dispersion grating, g395h ($r\approx2700$). our low-dispersion and medium-dispersion spectra cover the wavelength range $0.6-5.3\mu$m. we describe the selection of the spectroscopic targets, the strategy for the allocation of targets to micro-shutters, and the design of the observations. we present the public release of the reduced 2d and 1d spectra, and a description of the reduction and calibration process. we measure spectroscopic redshifts for 178 of the objects targeted extending up to $z=13.2$. we present a catalog of all emission lines detected at $s/n>5$, and our redshift determinations for the targets. combined with the first jades nircam data release, these public jades spectroscopic and imaging datasets provide a new foundation for discoveries of the infrared universe by the worldwide scientific community. | jades nirspec initial data release for the hubble ultra deep field: redshifts and line fluxes of distant galaxies from the deepest jwst cycle 1 nirspec multi-object spectroscopy |
we study gravitational waves (gws) induced by non-gaussian curvature perturbations. we calculate the density parameter per logarithmic frequency interval, ωgw(k ), given that the power spectrum of the curvature perturbation pr(k ) has a narrow peak at some small scale k*, with a local-type non-gaussianity, and constrain the nonlinear parameter fnl with the future lisa sensitivity curve as well as with constraints from the abundance of the primordial black holes (pbhs). we find that the non-gaussian contribution to ωgw increases as k3, peaks at k /k*=4 /√{3 }, and has a sharp cutoff at k =4 k*. the non-gaussian part can exceed the gaussian part if pr(k )fnl2≳1 . if both a slope ωgw(k )∝kβ with β ∼3 and the multiple-peak structure around a cutoff are observed, it can be recognized as a smoking gun of the primordial non-gaussianity. we also find that if pbhs with masses of 1 020 to 1 022 g are identified as cold dark matter of the universe, the corresponding gws must be detectable by lisa-like detectors, irrespective of the value of pr or fnl. | gravitational waves induced by non-gaussian scalar perturbations |
evidence for a stochastic gravitational wave background in the nhz frequency band is recently reported by four pulsar timing array collaborations nanograv, epta, cpta, and ppta. it can be interpreted by gravitational waves from collapsing domain walls in the early universe. we assume such domain walls arising from the spontaneous breaking of a z2 symmetry in a scalar field theory, where a tiny z2-violating potential is required to make domain walls unstable. we propose that this z2-violating potential is radiatively induced by a feeble yukawa coupling between the scalar field and a fermion field, which is also responsible for dark matter production via the freeze-in mechanism. combining the pulsar timing array data and the observed dark matter relic density, we find that the model parameters can be narrowed down to small ranges. | nano-hertz gravitational waves from collapsing domain walls associated with freeze-in dark matter in light of pulsar timing array observations |
quasars are the most luminous non-transient objects known and as a result they enable studies of the universe at the earliest cosmic epochs. despite extensive efforts, however, the quasar ulas j1120 + 0641 at redshift z = 7.09 has remained the only one known at z > 7 for more than half a decade. here we report observations of the quasar ulas j134208.10 + 092838.61 (hereafter j1342 + 0928) at redshift z = 7.54. this quasar has a bolometric luminosity of 4 × 1013 times the luminosity of the sun and a black-hole mass of 8 × 108 solar masses. the existence of this supermassive black hole when the universe was only 690 million years old—just five per cent of its current age—reinforces models of early black-hole growth that allow black holes with initial masses of more than about 104 solar masses or episodic hyper-eddington accretion. we see strong evidence of absorption of the spectrum of the quasar redwards of the lyman α emission line (the gunn-peterson damping wing), as would be expected if a significant amount (more than 10 per cent) of the hydrogen in the intergalactic medium surrounding j1342 + 0928 is neutral. we derive such a significant fraction of neutral hydrogen, although the exact fraction depends on the modelling. however, even in our most conservative analysis we find a fraction of more than 0.33 (0.11) at 68 per cent (95 per cent) probability, indicating that we are probing well within the reionization epoch of the universe. | an 800-million-solar-mass black hole in a significantly neutral universe at a redshift of 7.5 |
the most widely studied formation mechanism of a primordial black hole (pbh) is collapse of large-amplitude perturbation on small scales generated in single-field inflation. in this letter, we calculate one-loop correction to the large-scale power spectrum in such a model. we find models producing appreciable amount of pbhs induce nonperturbative coupling on large scale probed by cosmic microwave background radiation. we therefore conclude that pbh formation from cosmological perturbation theory in single-field inflation is ruled out. | ruling out primordial black hole formation from single-field inflation |
lisa, the laser interferometer space antenna, will usher in a new era in gravitational-wave astronomy. as the first anticipated space-based gravitational-wave detector, it will expand our view to the millihertz gravitational-wave sky, where a spectacular variety of interesting new sources abound: from millions of ultra-compact binaries in our galaxy, to mergers of massive black holes at cosmological distances; from the beginnings of inspirals that will venture into the ground-based detectors' view to the death spiral of compact objects into massive black holes, and many sources in between. central to realising lisa's discovery potential are waveform models, the theoretical and phenomenological predictions of the pattern of gravitational waves that these sources emit. this white paper is presented on behalf of the waveform working group for the lisa consortium. it provides a review of the current state of waveform models for lisa sources, and describes the significant challenges that must yet be overcome. | waveform modelling for the laser interferometer space antenna |
we present cosmological constraints from a cosmic shear analysis of the fourth data release of the kilo-degree survey (kids-1000), which doubles the survey area with nine-band optical and near-infrared photometry with respect to previous kids analyses. adopting a spatially flat standard cosmological model, we find s8 = σ8(ωm/0.3)0.5 = 0.759-0.021+0.024 for our fiducial analysis, which is in 3σ tension with the prediction of the planck legacy analysis of the cosmic microwave background. we compare our fiducial cosebis (complete orthogonal sets of e/b-integrals) analysis with complementary analyses of the two-point shear correlation function and band power spectra, finding the results to be in excellent agreement. we investigate the sensitivity of all three statistics to a number of measurement, astrophysical, and modelling systematics, finding our s8 constraints to be robust and dominated by statistical errors. our cosmological analysis of different divisions of the data passes the bayesian internal consistency tests, with the exception of the second tomographic bin. as this bin encompasses low-redshift galaxies, carrying insignificant levels of cosmological information, we find that our results are unchanged by the inclusion or exclusion of this sample. | kids-1000 cosmology: cosmic shear constraints and comparison between two point statistics |
four decades after its prediction, the axion remains the most compelling solution to the strong-cp problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing. this article reviews the experimental situation on several fronts. the microwave cavity experiment is making excellent progress in the search for dark matter axions in the μev range and may plausibly be extended up to 100 μev. within the past several years, however, researchers have realized that axions are pervasive throughout string theories, but with masses that fall naturally in the nev range, for which an nmr-based search is under development. both searches for axions emitted from the sun's burning core and purely laboratory experiments based on photon regeneration have recently made great progress, with ambitious projects proposed for the coming decade. each of these campaigns has pushed the state of the art in technology, enabling large gains in sensitivity and mass reach. furthermore, each modality has been exploited in order to search for more generalized axion-like particles, which we also discuss in this review. we are hopeful, even optimistic, that the next review of the subject will concern the discovery of the axion, its properties, and its exploitation as a probe of early universe cosmology and structure formation. | experimental searches for the axion and axion-like particles |
we explore the possibility that a confining first-order phase transition of a nearly-conformal dark sector generates the reported nanograv signal of a stochastic gravitational wave background. the visible standard model (sm) sector and the dark sector are initially thermally decoupled so that their temperatures are different. the nearly conformal phase transition is described by the shallow potential of a dilaton (or a radion in the 5d holographic perspective) generated by a new dark yang-mills field coupled to the conformal sector. for a dark sector only gravitationally connected with the visible sector, the nanograv signal is explained by the phase transition without contradicting the δneff constraint, together with a contribution from supermassive black hole binaries. while the dilaton and dark glueballs can be produced after the phase transition, they immediately decay into dark radiation, which can help ameliorate the hubble tension and be tested by the future cmb-s4 experiment. alternatively, for a dark conformal sector decaying into the visible sector after the phase transition, the δneff constraint is not applied and the phase transition can solely explain the nanograv signal. | nanograv signal from a dark conformal phase transition |
the forward physics facility (fpf) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the large hadron collider during the high luminosity era. located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the fpf will house experiments that will detect particles outside the acceptance of the existing large lhc experiments and will observe rare and exotic processes in an extremely low-background environment. in this work, we summarize the current status of plans for the fpf, including recent progress in civil engineering in identifying promising sites for the fpf and the experiments currently envisioned to realize the fpf's physics potential. we then review the many standard model and new physics topics that will be advanced by the fpf, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of tev neutrinos of all three flavors, aspects of perturbative and non-perturbative qcd, and high-energy astroparticle physics. | the forward physics facility: sites, experiments, and physics potential |
hyper suprime-cam (hsc) is a wide-field imaging camera on the prime focus of the 8.2-m subaru telescope on the summit of mauna kea in hawaii. a team of scientists from japan, taiwan, and princeton university is using hsc to carry out a 300-night multi-band imaging survey of the high-latitude sky. the survey includes three layers: the wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. the deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the ultradeep layer goes almost a magnitude fainter still in two pointings of hsc (a total of 3.5 deg2). here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. this paper serves as an introduction to a special issue of the publications of the astronomical society of japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey. | the hyper suprime-cam ssp survey: overview and survey design |
local measurements of the hubble parameter are increasingly in tension with the value inferred from a λcdm fit to the cosmic microwave background (cmb) data. in this paper, we construct scenarios in which evolving scalar fields significantly ease this tension by adding energy to the universe around recombination in a narrow redshift window. we identify solutions with scalar field potential v ∝ϕ2n that have simple asymptotic behavior, both oscillatory (rocking) and rolling. these solutions consistently describe both the field evolution and its fluctuations without approximation. our findings differ qualitatively from some of the existing literature, which rely upon a coarse-grained fluid description. combining cmb data with low-redshift measurements, the best fit model has n = 2 with a significantly higher value of the hubble constant as compared to a λcdm fit to the same data. future measurements of the late-time amplitude of matter fluctuations and of the reionization history could help distinguish these models from competing solutions. | rock 'n' roll solutions to the hubble tension |
the dwarf spheroidal satellite galaxies (dsphs) of the milky way are some of the most dark matter (dm) dominated objects known. we report on γ -ray observations of milky way dsphs based on six years of fermi large area telescope data processed with the new pass8 event-level analysis. none of the dsphs are significantly detected in γ rays, and we present upper limits on the dm annihilation cross section from a combined analysis of 15 dsphs. these constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for dm of mass ≲100 gev annihilating via quark and τ -lepton channels. | searching for dark matter annihilation from milky way dwarf spheroidal galaxies with six years of fermi large area telescope data |
we present a catalog of 536 fast radio bursts (frbs) detected by the canadian hydrogen intensity mapping experiment fast radio burst (chime/frb) project between 400 and 800 mhz from 2018 july 25 to 2019 july 1, including 62 bursts from 18 previously reported repeating sources. the catalog represents the first large sample, including bursts from repeaters and nonrepeaters, observed in a single survey with uniform selection effects. this facilitates comparative and absolute studies of the frb population. we show that repeaters and apparent nonrepeaters have sky locations and dispersion measures (dms) that are consistent with being drawn from the same distribution. however, bursts from repeating sources differ from apparent nonrepeaters in intrinsic temporal width and spectral bandwidth. through injection of simulated events into our detection pipeline, we perform an absolute calibration of selection effects to account for systematic biases. we find evidence for a population of frbs-composing a large fraction of the overall population-with a scattering time at 600 mhz in excess of 10 ms, of which only a small fraction are observed by chime/frb. we infer a power-law index for the cumulative fluence distribution of $\alpha =-1.40\pm 0.11({\rm{stat.}}{)}_{-0.09}^{+0.06}({\rm{sys.}})$ , consistent with the -3/2 expectation for a nonevolving population in euclidean space. we find that α is steeper for high-dm events and shallower for low-dm events, which is what would be expected when dm is correlated with distance. we infer a sky rate of $[820\pm 60({\rm{stat.}}{)}_{-200}^{+220}({\rm{sys.}})]/{\rm{sky}}/{\rm{day}}$ above a fluence of 5 jy ms at 600 mhz, with a scattering time at 600 mhz under 10 ms and dm above 100 pc cm-3. | the first chime/frb fast radio burst catalog |
we present new arcminute-resolution maps of the cosmic microwave background temperature and polarization anisotropy from the atacama cosmology telescope, using data taken from 2013-2016 at 98 and 150 ghz. the maps cover more than 17,000 deg2, the deepest 600 deg2 with noise levels below 10μk-arcmin. we use the power spectrum derived from almost 6,000 deg2 of these maps to constrain cosmology. the act data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. from these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, h0. by combining act data with large-scale information from wmap we measure h0=67.6± 1.1 km/s/mpc, at 68% confidence, in excellent agreement with the independently-measured planck satellite estimate (from act alone we find h0=67.9± 1.5 km/s/mpc). the λcdm model provides a good fit to the act data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1σ the number of relativistic species, the primordial helium fraction, and the running of the spectral index are consistent with λcdm predictions to within 1.5-2.2σ. we compare act, wmap, and planck at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding cmb large-scale information that act does not measure. the dr4 products presented here will be publicly released on the nasa legacy archive for microwave background data analysis. | the atacama cosmology telescope: dr4 maps and cosmological parameters |
recently, observational hints for supermassive black holes have been accumulating, which has inspired ones to wonder: can primordial black holes (pbhs) be supermassive, in particular with the mass $m\gtrsim 10^{9}m_\odot$? a supercritical bubble (with an inflating baby universe inside it) that nucleated during inflation can develop into a pbh in our observable universe. here, we find that when the inflaton slowly passes by a neighboring vacuum, the nucleating rate of supercritical bubbles would inevitably attain a peak, so the mass distribution of multiverse pbhs, and the mass of peak can be up to $m\gtrsim 10^{11}m_\odot$. thus our mechanism naturally provides a primordial origin of supermassive bhs. | supermassive primordial black holes in multiverse: for nano-hertz gravitational wave and high-redshift jwst galaxies |
although dark matter is a central element of modern cosmology, the history of how it became accepted as part of the dominant paradigm is often ignored or condensed into an anecdotal account focused around the work of a few pioneering scientists. the aim of this review is to provide a broader historical perspective on the observational discoveries and the theoretical arguments that led the scientific community to adopt dark matter as an essential part of the standard cosmological model. | history of dark matter |
gravitational waves (gws) were recently detected for the first time. this revolutionary discovery opens a new way of learning about particle physics through gws from first-order phase transitions (fopts) in the early universe. fopts could occur when new fundamental symmetries are spontaneously broken down to the standard model and are a vital ingredient in solutions of the matter anti-matter asymmetry problem. the purpose of our work is to review the path from a particle physics model to gws, which contains many specialized parts, so here we provide a timely review of all the required steps, including: (i) building a finite-temperature effective potential in a particle physics model and checking for fopts; (ii) computing transition rates; (iii) analyzing the dynamics of bubbles of true vacuum expanding in a thermal plasma; (iv) characterizing a transition using thermal parameters; and, finally, (v) making predictions for gw spectra using the latest simulations and theoretical results and considering the detectability of predicted spectra at future gw detectors. for each step we emphasize the subtleties, advantages and drawbacks of different methods, discuss open questions and review the state-of-art approaches available in the literature. this provides everything a particle physicist needs to begin exploring gw phenomenology. | cosmological phase transitions: from perturbative particle physics to gravitational waves |
whether or not the primordial gravitational wave (gw) produced during inflation is sufficiently strong to be observable, gws are necessarily produced from the primordial curvature perturbations in the second order of perturbation. the induced gws can be enhanced by curvature perturbations enhanced at small scales or by the presence of matter-dominated stages of the cosmological history. we analytically calculate the integral in the expression of the power spectrum of the induced gws, which is a universal part independent of the spectrum of the primordial curvature perturbations. this makes the subsequent numerical integrals significantly easy. in simple cases, we derive fully analytic formulas for the induced gw spectrum. | semianalytic calculation of gravitational wave spectrum nonlinearly induced from primordial curvature perturbations |
we consider the possibility that the black-hole (bh) binary detected by ligo may be a signature of dark matter. interestingly enough, there remains a window for masses 20 m⊙≲mbh≲100 m⊙ where primordial black holes (pbhs) may constitute the dark matter. if two bhs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. the bound bhs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. still, reasonable estimates span a range that overlaps the 2 - 53 gpc-3 yr-1 rate estimated from gw150914, thus raising the possibility that ligo has detected pbh dark matter. pbh mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. they may be distinguished from mergers of bhs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. next-generation experiments will be invaluable in performing these tests. | did ligo detect dark matter? |
the second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. to support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the universe. | exploring the sensitivity of next generation gravitational wave detectors |
various pulsar timing array (pta) experiments (nanograv, epta, ppta, cpta, including data from inpta) very recently reported evidence for excess red common-spectrum signals in their latest datasets, with inter-pulsar correlations following the hellings-downs pattern, pointing to a stochastic gravitational wave background (sgwb) origin. focusing for concreteness on the nanograv signal (given that all signals are in good agreement between each other), i inspect whether it supports an inflationary sgwb explanation, finding that such an interpretation calls for an extremely blue tensor spectrum, with spectral index nt ≃ 1.8 ± 0.3, while big bang nucleosynthesis limits require a very low reheating scale, trh ≲ 10 gev . while not impossible, an inflationary origin for the pta signal is barely tenable: within well-motivated inflationary models it is hard to achieve such a blue tilt, whereas models who do tend to predict sizeable non-gaussianities, excluded by observations. intriguingly, ekpyrotic models naturally predict a sgwb with spectral index nt = 2, although with an amplitude too suppressed to be able to explain the signal detected by pta experiments. finally, i provide explicit expressions for a bivariate gaussian approximation to the joint posterior distribution for the intrinsic-noise amplitude and spectral index of the nanograv signal, which can facilitate extending similar analyses to different theoretical signals. | inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments |
over recent decades, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description. here we review various torsional constructions, from teleparallel, to einstein-cartan, and metric-affine gauge theories, resulting in extending torsional gravity in the paradigm of f (t) gravity, where f (t) is an arbitrary function of the torsion scalar. based on this theory, we further review the corresponding cosmological and astrophysical applications. in particular, we study cosmological solutions arising from f (t) gravity, both at the background and perturbation levels, in different eras along the cosmic expansion. the f (t) gravity construction can provide a theoretical interpretation of the late-time universe acceleration, alternative to a cosmological constant, and it can easily accommodate with the regular thermal expanding history including the radiation and cold dark matter dominated phases. furthermore, if one traces back to very early times, for a certain class of f (t) models, a sufficiently long period of inflation can be achieved and hence can be investigated by cosmic microwave background observations—or, alternatively, the big bang singularity can be avoided at even earlier moments due to the appearance of non-singular bounces. various observational constraints, especially the bounds coming from the large-scale structure data in the case of f (t) cosmology, as well as the behavior of gravitational waves, are described in detail. moreover, the spherically symmetric and black hole solutions of the theory are reviewed. additionally, we discuss various extensions of the f (t) paradigm. finally, we consider the relation with other modified gravitational theories, such as those based on curvature, like f (r) gravity, trying to illuminate the subject of which formulation, or combination of formulations, might be more suitable for quantization ventures and cosmological applications. | f(t) teleparallel gravity and cosmology |
a century ago, einstein formulated his elegant and elaborate theory of general relativity, which has so far withstood a multitude of empirical tests with remarkable success. notwithstanding the triumphs of einstein's theory, the tenacious challenges of modern cosmology and of particle physics have motivated the exploration of further generalised theories of space-time. even though einstein's interpretation of gravity in terms of the curvature of space-time is commonly adopted, the assignment of geometrical concepts to gravity is ambiguous because general relativity allows three entirely different, but equivalent approaches of which einstein's interpretation is only one. from a field-theoretical perspective, however, the construction of a consistent theory for a lorentz-invariant massless spin-2 particle uniquely leads to general relativity. keeping lorentz invariance then implies that any modification of general relativity will inevitably introduce additional propagating degrees of freedom into the gravity sector. adopting this perspective, we will review the recent progress in constructing consistent field theories of gravity based on additional scalar, vector and tensor fields. within this conceptual framework, we will discuss theories with galileons, with lagrange densities as constructed by horndeski and beyond, extended to dhost interactions, or containing generalised proca fields and extensions thereof, or several proca fields, as well as bigravity theories and scalar-vector-tensor theories. we will review the motivation of their inception, different formulations, and essential results obtained within these classes of theories together with their empirical viability. | a systematic approach to generalisations of general relativity and their cosmological implications |
we review theories of dark matter (dm) beyond the collisionless paradigm, known as self-interacting dark matter (sidm), and their observable implications for astrophysical structure in the universe. self-interactions are motivated, in part, due to the potential to explain long-standing (and more recent) small scale structure observations that are in tension with collisionless cold dm (cdm) predictions. simple particle physics models for sidm can provide a universal explanation for these observations across a wide range of mass scales spanning dwarf galaxies, low and high surface brightness spiral galaxies, and clusters of galaxies. at the same time, sidm leaves intact the success of λcdm cosmology on large scales. this report covers the following topics: (1) small scale structure issues, including the core-cusp problem, the diversity problem for rotation curves, the missing satellites problem, and the too-big-to-fail problem, as well as recent progress in hydrodynamical simulations of galaxy formation; (2) n-body simulations for sidm, including implications for density profiles, halo shapes, substructure, and the interplay between baryons and self-interactions; (3) semi-analytic jeans-based methods that provide a complementary approach for connecting particle models with observations; (4) merging systems, such as cluster mergers (e.g., the bullet cluster) and minor infalls, along with recent simulation results for mergers; (5) particle physics models, including light mediator models and composite dm models; and (6) complementary probes for sidm, including indirect and direct detection experiments, particle collider searches, and cosmological observations. we provide a summary and critical look for all current constraints on dm self-interactions and an outline for future directions. | dark matter self-interactions and small scale structure |
a cosmic first-order phase transition occurring at the mev scale provides an attractive explanation for the nano-hertz gravitational wave (gw) background, which is indicated by the recent pulsar timing array data from the nanograv, cpta, epta, and ppta collaborations. we propose this explanation can be further tested at the colliders if the hidden sector couples to the standard model sector via the higgs portal. through a careful analysis of the thermal history in the hidden sector, we demonstrate that in order to explain the observed gw signal, the portal coupling must be sizable so that it can be probed through higgs invisible decay at the lhc or future lepton colliders such as cepc, ilc, and fcc-ee. our research offers a promising avenue to uncover the physical origin of the nano-hertz gws through particle physics experiments. | collider test of nano-hertz gravitational waves from pulsar timing arrays |
recently, strong evidence for a gravitational wave background has been reported by collaborations of pulsar timing arrays (pta). in the framework of scalar-induced gravitational waves (sigws), we concurrently investigate the second and third order gravitational waves by jointly analyzing pta data, alongside big-bang nucleosynthesis (bbn), and cosmic microwave background (cmb) datasets. we determine the primordial curvature spectral amplitude as $0.021<a_\zeta<0.085$ and the spectral peak frequency as $10^{-7.3}\ \mathrm{hz}<f_\ast<10^{-6.3}\ \mathrm{hz}$ at a 95\% confidence interval, pointing towards a mass range for primordial black holes of $10^{-4.5}m_\odot<m_{\mathrm{pbh}}<10^{-2.5}m_\odot$. our findings suggest that third order gravitational waves contribute more significantly to the integrated energy density than the second order ones when $a_\zeta\gtrsim0.06$. furthermore, we expect future pta projects to validate these findings and provide robust means to investigate the genesis and evolution of the universe, especially inflation. | constraints on scalar-induced gravitational waves up to third order from joint analysis of bbn, cmb, and pta data |
the remarkable hubble space telescope (hst) data sets from the candels, hudf09, hudf12, ers, and borg/hippies programs have allowed us to map the evolution of the rest-frame uv luminosity function (lf) from z∼ 10 to z∼ 4. we develop new color criteria that more optimally utilize the full wavelength coverage from the optical, near-ir, and mid-ir observations over our search fields, while simultaneously minimizing the incompleteness and eliminating redshift gaps. we have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z∼ 4, z∼ 5, z∼ 6, z∼ 7, z∼ 8, and z∼ 10, respectively, from the ∼1000 arcmin2 area covered by these data sets. this sample of >10,000 galaxy candidates at z≥slant 4 is by far the largest assembled to date with hst. the selection of z ∼ 4-8 candidates over the five candels fields allows us to assess the cosmic variance; the largest variations are at z≥slant 7. our new lf determinations at z∼ 4 and z∼ 5 span a 6 mag baseline and reach to -16 ab mag. these determinations agree well with previous estimates, but the larger samples and volumes probed here result in a more reliable sampling of \gt {{l}*} galaxies and allow us to reassess the form of the uv lfs. our new lf results strengthen our earlier findings to 3.4σ significance for a steeper faint-end slope of the uv lf at z\gt 4, with α evolving from α =-1.64+/- 0.04 at z∼ 4 to α =-2.06+/- 0.13 at z∼ 7 (and α =-2.02+/- 0.23 at z∼ 8), consistent with that expected from the evolution of the halo mass function. we find less evolution in the characteristic magnitude m* from z∼ 7 to z∼ 4; the observed evolution in the lf is now largely represented by changes in {{φ }*}. no evidence for a non-schechter-like form to the z ∼ 4-8 lfs is found. a simple conditional lf model based on halo growth and evolution in the m/l ratio (\propto {{(1+z)}-1.5}) of halos provides a good representation of the observed evolution. based on observations obtained with megaprime/megacam, a joint project of cfht and cea/irfu, at the canada-france-hawaii telescope (cfht), which is operated by the national research council (nrc) of canada, the institut national des science 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 available at the canadian astronomy data centre as part of the canada-france-hawaii telescope legacy survey, a collaborative project of nrc and cnrs. | uv luminosity functions at redshifts z ∼ 4 to z ∼ 10: 10,000 galaxies from hst legacy fields |
recently, the nanograv, ppta, epta and cpta collaborations reported compelling evidence of the existence of the stochastic gravitational-wave background (sgwb). the amplitude and spectrum of this inferred gravitational-wave background align closely with the astrophysical predictions for a signal originating from the population of supermassive black-hole binaries. in light of these findings, we explore the possibility to detect dark matter spikes surrounding massive black holes, which could potentially impact the gravitational-wave waveform and modulate the sgwb. we demonstrate that the smbh binary evolution induced by the combined effects of gw radiation and the dynamical friction of the dark matter spike exhibits detectable manifestations within the nhz frequency range of the sgwb. | dark matter spike surrounding supermassive black holes binary and the nanohertz stochastic gravitational wave background |
several pulsar timing array collaborations recently reported evidence of a stochastic gravitational wave background (sgwb) at nhz frequencies. whilst the sgwb could originate from the merger of supermassive black holes, it could be a signature of new physics near the 100 mev scale. supercooled first-order phase transitions (fopts) that end at the 100 mev scale are intriguing explanations, because they could connect the nhz signal to new physics at the electroweak scale or beyond. here, however, we provide a clear demonstration that it is not simple to create a nhz signal from a supercooled phase transition, due to two crucial issues that should be checked in any proposed supercooled explanations. as an example, we use a model based on non-linearly realized electroweak symmetry that has been cited as evidence for a supercooled explanation. first, we show that a fopt cannot complete for the required transition temperature of around 100 mev. such supercooling implies a period of vacuum domination that hinders bubble percolation and transition completion. second, we show that even if completion is not required or if this constraint is evaded, the universe typically reheats to the scale of any physics driving the fopt. the hierarchy between the transition and reheating temperature makes it challenging to compute the spectrum of the sgwb. | can supercooled phase transitions explain the gravitational wave background observed by pulsar timing arrays? |
we present the calibration and reduction of event horizon telescope (eht) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy m87 and the quasar 3c 279, taken during the 2017 april 5-11 observing campaign. these global very long baseline interferometric observations include for the first time the highly sensitive atacama large millimeter/submillimeter array (alma); reaching an angular resolution of 25 μas, with characteristic sensitivity limits of ∼1 mjy on baselines to alma and ∼10 mjy on other baselines. the observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. in response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the eht. the final data products include calibrated total intensity amplitude and phase information. they are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. the m87 data reveal the presence of two nulls in correlated flux density at ∼3.4 and ∼8.3 gλ and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. these measurements provide the first opportunity to image horizon-scale structure in m87. | first m87 event horizon telescope results. iii. data processing and calibration |
we present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg. reconstructed from cmb measurements made by the atacama cosmology telescope (act) from 2017 to 2021. in combination with bao measurements (from sdss and 6df), we obtain the amplitude of matter fluctuations $\sigma_8 = 0.819 \pm 0.015$ at 1.8% precision, $s_8\equiv\sigma_8({\omega_{\rm m}}/0.3)^{0.5}=0.840\pm0.028$ and the hubble constant $h_0= (68.3 \pm 1.1)\, \text{km}\,\text{s}^{-1}\,\text{mpc}^{-1}$ at 1.6% precision. a joint constraint with cmb lensing measured by the planck satellite yields even more precise values: $\sigma_8 = 0.812 \pm 0.013$, $s_8\equiv\sigma_8({\omega_{\rm m}}/0.3)^{0.5}=0.831\pm0.023$ and $h_0= (68.1 \pm 1.0)\, \text{km}\,\text{s}^{-1}\,\text{mpc}^{-1}$. these measurements agree well with $\lambda$cdm-model extrapolations from the cmb anisotropies measured by planck. to compare these constraints to those from the kids, des, and hsc galaxy surveys, we revisit those data sets with a uniform set of assumptions, and find $s_8$ from all three surveys are lower than that from act+planck lensing by varying levels ranging from 1.7-2.1$\sigma$. these results motivate further measurements and comparison, not just between the cmb anisotropies and galaxy lensing, but also between cmb lensing probing $z\sim 0.5-5$ on mostly-linear scales and galaxy lensing at $z\sim 0.5$ on smaller scales. we combine our cmb lensing measurements with cmb anisotropies to constrain extensions of $\lambda$cdm, limiting the sum of the neutrino masses to $\sum m_{\nu} < 0.12$ ev (95% c.l.), for example. our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the $\lambda$cdm model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based cmb surveys. | the atacama cosmology telescope: dr6 gravitational lensing map and cosmological parameters |
in this paper we describe the survey design for the ultradeep nirspec and nircam observations before the epoch of reionization (uncover) cycle 1 jwst treasury program, which executed its early imaging component in november 2022. the uncover survey includes ultradeep ($\sim29-30\mathrm{ab}$) imaging of $\sim$45 arcmin$^2$ on and around the well-studied abell 2744 galaxy cluster at $z=0.308$ and will follow-up ${\sim}500$ galaxies with extremely deep low-resolution spectroscopy with the nirspec/prism during the summer of 2023. we describe the science goals, survey design, target selection, and planned data releases. we also present and characterize the depths of the first nircam imaging mosaic, highlighting previously unparalleled resolved and ultradeep 2-4 micron imaging of known objects in the field. the uncover primary nircam mosaic spans 28.8 arcmin$^2$ in seven filters (f115w, f150w, f200w, f277w, f356w, f410m, f444w) and 16.8 arcmin$^2$ in our niriss parallel (f115w, f150w, f200w, f356w, and f444w). to maximize early community use of the treasury data set, we publicly release full reduced mosaics of public jwst imaging including 45 arcmin$^2$ nircam and 17 arcmin$^2$ niriss mosaics on and around the abell 2744 cluster, including the hubble frontier field primary and parallel footprints. | the jwst uncover treasury survey: ultradeep nirspec and nircam observations before the epoch of reionization |
the current cosmological probes have provided a fantastic confirmation of the standard λ cold dark matter cosmological model, which has been constrained with unprecedented accuracy. however, with the increase of the experimental sensitivity, a few statistically significant tensions between different independent cosmological datasets emerged. while these tensions can be in part the result of systematic errors, the persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the need for new physics. in this letter of interest we will focus on the 4.4 σ tension between the planck estimate of the hubble constant h0 and the sh0es collaboration measurements. after showing the h0 evaluations made from different teams using different methods and geometric calibrations, we will list a few interesting models of new physics that could solve this tension and discuss how the next decade's experiments will be crucial. | cosmology intertwined ii: the hubble constant tension |
we investigate the potential for observing gravitational waves from cosmological phase transitions with lisa in light of recent theoretical and experimental developments. our analysis is based on current state-of-the-art simulations of sound waves in the cosmic fluid after the phase transition completes. we discuss the various sources of gravitational radiation, the underlying parameters describing the phase transition and a variety of viable particle physics models in this context, clarifying common misconceptions that appear in the literature and identifying open questions requiring future study. we also present a web-based tool, ptplot, that allows users to obtain up-to-date detection prospects for a given set of phase transition parameters at lisa. | detecting gravitational waves from cosmological phase transitions with lisa: an update |
primordial black holes (pbhs) can be formed from the collapse of large-amplitude perturbation on small scales in the early universe. such an enhanced spectrum can be realized by introducing a flat region in the potential of single-field inflation, which makes the inflaton go into a temporary ultraslow-roll (usr) period. in this paper, we calculate the bispectrum of curvature perturbation in such a scenario. we explicitly confirm that bispectrum satisfies maldacena's theorem. at the end of the usr period, the bispectrum is generated by bulk interaction and field redefinition. at the end of inflation, bispectrum is generated only by bulk interaction. we also calculate the one-loop correction to the power spectrum from the bispectrum, called the source method. we find it consistent with the calculation of one-loop correction from the second-order expansion of in-in perturbation theory. in the last section of this paper, we write our response to criticism to our letter [arxiv:2211.03395] by [arxiv:2301.00599]. we argue that the criticism is based on the incorrect use of maldacena's theorem. after fixing such a mistake, we show that the one-loop correction in our letter is reproduced in the source method as well. this confirms our letter's conclusion that rules out pbh formation from single-field inflation. | response to criticism on "ruling out primordial black hole formation from single-field inflation\'\': a note on bispectrum and one-loop correction in single-field inflation with primordial black hole formation |
we review sterile neutrinos as possible dark matter candidates. after a short summary on the role of neutrinos in cosmology and particle physics, we give a comprehensive overview of the current status of the research on sterile neutrino dark matter. first we discuss the motivation and limits obtained through astrophysical observations. second, we review different mechanisms of how sterile neutrino dark matter could have been produced in the early universe. finally, we outline a selection of future laboratory searches for kev-scale sterile neutrinos, highlighting their experimental challenges and discovery potential. | sterile neutrino dark matter |
a standard scenario to form primordial black holes in the early universe is based on a phase of ultra-slow-roll in single-field inflation when the amplitude of the short scale modes is enhanced compared to the cmb plateau. based on general arguments, we show that the loop corrections to the large-scale linear power spectrum from the short modes are small and conclude that the scenario is not ruled out. | the primordial black hole formation from single-field inflation is not ruled out |
euclid is a european space agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program. the main goal of euclid is to understand the origin of the accelerated expansion of the universe. euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. although the main driver for euclid is the nature of dark energy, euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. in this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. we discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. this review has been planned and carried out within euclid's theory working group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the euclid mission. | cosmology and fundamental physics with the euclid satellite |
we present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ∼450 deg2 of imaging data from the kilo degree survey (kids). for a flat λ cold dark matter (λcdm) cosmology with a prior on h0 that encompasses the most recent direct measurements, we find s_8≡ σ _8√{ω _m/0.3}=0.745± 0.039. this result is in good agreement with other low-redshift probes of large-scale structure, including recent cosmic shear results, along with pre-planck cosmic microwave background constraints. a 2.3σ tension in s8 and `substantial discordance' in the full parameter space is found with respect to the planck 2015 results. we use shear measurements for nearly 15 million galaxies, determined with a new improved `self-calibrating' version of lensfit validated using an extensive suite of image simulations. four-band ugri photometric redshifts are calibrated directly with deep spectroscopic surveys. the redshift calibration is confirmed using two independent techniques based on angular cross-correlations and the properties of the photometric redshift probability distributions. our covariance matrix is determined using an analytical approach, verified numerically with large mock galaxy catalogues. we account for uncertainties in the modelling of intrinsic galaxy alignments and the impact of baryon feedback on the shape of the non-linear matter power spectrum, in addition to the small residual uncertainties in the shear and redshift calibration. the cosmology analysis was performed blind. our high-level data products, including shear correlation functions, covariance matrices, redshift distributions, and monte carlo markov chains are available at http://kids.strw.leidenuniv.nl. | kids-450: cosmological parameter constraints from tomographic weak gravitational lensing |
for a discrete symmetry that is anomalous under qcd, the domain walls produced in the early universe from its spontaneous breaking can naturally annihilate due to qcd instanton effects. the gravitational waves generated from wall annihilation have their amplitude and frequency determined by both the discrete symmetry breaking scale and the qcd scale. the evidence of stochastic gravitational waves at nanohertz observed by pulsar timing array experiments suggests that the discrete-symmetry-breaking scale is around 100 tev, assuming the domain-wall explanation. the annihilation temperature is about 100 mev, which could naturally be below the qcd phase transition temperature. we point out that the qcd phase transition within some domains with an effective large qcd θ angle could be a first-order one. to derive the phase diagram in θ and temperature, we adopt a phenomenological linear sigma model with three quark flavors. the domain-wall explanation for the nanograv, epta, ppta and cpta results hints at a first-order qcd phase transition, which predicts additional gravitational waves at higher frequencies. if the initial formation of domain walls is also a first-order process, this class of domain-wall models predicts an interesting gravitational wave spectroscopy with frequencies spanning more than ten orders of magnitude, from nanohertz to 100 hz. | qcd-collapsed domain walls: qcd phase transition and gravitational wave spectroscopy |
in this letter, we derive for the first time a characteristic three-peaked gw signal within the framework of no-scale supergravity, being the low-energy limit of superstring theory. we concentrate on the primordial gravitational wave (gw) spectrum induced due to second-order gravitational interactions by inflationary curvature perturbations as well as by isocurvature energy density perturbations of primordial black holes (pbhs) both amplified due to the presence of an early matter-dominated era (emd) era before big bang nucleosythesis (bbn). in particular, we work with inflection-point inflationary potentials naturally-realised within wess-zumino type no-scale supergravity and giving rise to the formation of microscopic pbhs triggering an emd era and evaporating before bbn. remarkably, we obtain an abundant production of gravitational waves at the frequency ranges of $\mathrm{nhz}$, $\mathrm{hz}$ and $\mathrm{khz}$ and in strong agreement with pulsar time array (pta) gw data. interestingly enough, a simultaneous detection of all three $\mathrm{nhz}$, $\mathrm{hz}$ and $\mathrm{khz}$ gw peaks can constitute a potential observational signature for no-scale supergravity. | gravitational wave signatures of no-scale supergravity in nanograv and beyond |
we examine the possibility of primordial black holes (pbhs) formation in single-field models of inflation. using the adiabatic or wave function renormalization scheme in the short-range modes, we show that one-loop correction to the power spectrum is free from quadratic uv divergence. we consider a framework in which pbhs are produced during the transition from slow roll (sr) to ultra slow roll (usr) followed by the end of inflation. we demonstrate that the renormalized power spectrum softens the contribution of the logarithmic ir divergence and severely restricts the possible mass range of produced pbhs in the said transition, namely, $m_{\rm pbh}\sim 10^{2}{\rm gm}$ ala a no-go theorem. in particular, we find that the produced pbhs are short-lived ($t^{\rm evap}_{\rm pbh}\sim 10^{-20}{\rm sec}$) and the corresponding number of e-folds in the usr region is restricted to $\delta n_{\rm usr}\approx 2$. | no-go for the formation of heavy mass primordial black holes in single field inflation |
context. measurement of the galactic neutral atomic hydrogen (h i) column density, nh i, and brightness temperatures, tb, is of high scientific value for a broad range of astrophysical disciplines. in the past two decades, one of the most-used legacy h i datasets has been the leiden/argentine/bonn survey (lab).aims: we release the h i 4π survey (hi4pi), an all-sky database of galactic h i, which supersedes the lab survey.methods: the hi4pi survey is based on data from the recently completed first coverage of the effelsberg-bonn h i survey (ebhis) and from the third revision of the galactic all-sky survey (gass). ebhis and gass share similar angular resolution and match well in sensitivity. combined, they are ideally suited to be a successor to lab.results: the new hi4pi survey outperforms the lab in angular resolution (ϑfwhm = 16´´.2) and sensitivity (σrms = 43 mk). moreover, it has full spatial sampling and thus overcomes a major drawback of lab, which severely undersamples the sky. we publish all-sky column density maps of the neutral atomic hydrogen in the milky way, along with full spectroscopic data, in several map projections including healpix. hi4pi datasets are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/594/a116 | hi4pi: a full-sky h i survey based on ebhis and gass |
we extend the cosmological bootstrap to correlators involving massless particles with spin. in de sitter space, these correlators are constrained both by symmetries and by locality. in particular, the de sitter isometries become conformal symmetries on the future boundary of the spacetime, which are reflected in a set of ward identities that the boundary correlators must satisfy. we solve these ward identities by acting with weight-shifting operators on scalar seed solutions. using this weight-shifting approach, we derive three- and four-point correlators of massless spin-1 and spin-2 fields with conformally coupled scalars. four-point functions arising from tree-level exchange are singular in particular kinematic configurations, and the coefficients of these singularities satisfy certain factorization properties. we show that in many cases these factorization limits fix the structure of the correlators uniquely, without having to solve the conformal ward identities. the additional constraint of locality for massless spinning particles manifests itself as current conservation on the boundary. we find that the four-point functions only satisfy current conservation if the s, t, and u-channels are related to each other, leading to nontrivial constraints on the couplings between the conserved currents and other operators in the theory. for spin-1 currents this implies charge conservation, while for spin-2 currents we recover the equivalence principle from a purely boundary perspective. for multiple spin-1 fields, we recover the structure of yang-mills theory. finally, we apply our methods to slow-roll inflation and derive a few phenomenologically relevant scalar-tensor three-point functions. | the cosmological bootstrap: spinning correlators from symmetries and factorization |
event horizon telescope (eht) observations at 230 ghz have now imaged polarized emission around the supermassive black hole in m87 on event-horizon scales. this polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. here we compare the resolved polarization structure observed by the eht, along with simultaneous unresolved observations with the atacama large millimeter/submillimeter array, to expectations from theoretical models. the low fractional linear polarization in the resolved image suggests that the polarization is scrambled on scales smaller than the eht beam, which we attribute to faraday rotation internal to the emission region. we estimate the average density ne ∼ 104-7 cm-3, magnetic field strength b ∼ 1-30 g, and electron temperature te ∼ (1-12) × 1010 k of the radiating plasma in a simple one-zone emission model. we show that the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields in the emission region. in a quantitative comparison with a large library of simulated polarimetric images from general relativistic magnetohydrodynamic (grmhd) simulations, we identify a subset of physical models that can explain critical features of the polarimetric eht observations while producing a relativistic jet of sufficient power. the consistent grmhd models are all of magnetically arrested accretion disks, where near-horizon magnetic fields are dynamically important. we use the models to infer a mass accretion rate onto the black hole in m87 of (3-20) × 10-4 m⊙ yr-1. | first m87 event horizon telescope results. viii. magnetic field structure near the event horizon |
axions are hypothetical particles that may explain the observed dark matter density and the non-observation of a neutron electric dipole moment. an increasing number of axion laboratory searches are underway worldwide, but these efforts are made difficult by the fact that the axion mass is largely unconstrained. if the axion is generated after inflation there is a unique mass that gives rise to the observed dark matter abundance; due to nonlinearities and topological defects known as strings, computing this mass accurately has been a challenge for four decades. recent works, making use of large static lattice simulations, have led to largely disparate predictions for the axion mass, spanning the range from 25 microelectronvolts to over 500 microelectronvolts. in this work we show that adaptive mesh refinement simulations are better suited for axion cosmology than the previously-used static lattice simulations because only the string cores require high spatial resolution. using dedicated adaptive mesh refinement simulations we obtain an over three order of magnitude leap in dynamic range and provide evidence that axion strings radiate their energy with a scale-invariant spectrum, to within ~5% precision, leading to a mass prediction in the range (40,180) microelectronvolts. | dark matter from axion strings with adaptive mesh refinement |
in this letter we evaluate whether the gravitational wave background recently observed by a number of different pulsar timing arrays could be due to merging primordial supermassive black hole binaries. we find that for homogeneously distributed primordial black holes this possibility is inconsistent with strong cosmological and astrophysical constraints on their total abundance. if the distribution exhibits some clustering, however, the merger rate will in general be enhanced, opening the window for a consistent interpretation of the pta data in terms of merging primordial black holes. | do pulsar timing arrays observe merging primordial black holes? |
several pulsar timing array (pta) collaborations have recently provided strong evidence for a nhz stochastic gravitational-wave background (sgwb). here we investigate the implications of a first-order phase transition occurring within the early universe's dark quantum chromodynamics (dqcd) epoch, specifically within the framework of the mirror twin higgs dark sector model. our analysis indicates a distinguishable sgwb signal originating from this phase transition, which can explain the measurements obtained by ptas. remarkably, a significant portion of the parameter space for the sgwb signal also effectively resolves the existing tensions in both the $h_0$ and $s_8$ measurements in cosmology. this intriguing correlation suggests a possible common origin of these three phenomena for $0.2 < \delta n_{\rm eff} < 0.5$, where the mirror dark matter component constitutes about $30\%$ of the total dark matter abundance. next generation cmb experiment such as cmb-s4 is able to test this parameter region. | mirror qcd phase transition as the origin of the nanohertz stochastic gravitational-wave background |
the origin of interstellar and intergalactic magnetic fields remains largely unknown. one possibility is that they are related to the primordial magnetic fields (pmfs) produced by, for instance, the phase transitions of the early universe. in this letter, we show that the pmf-induced turbulence generated at around the qcd phase transition epoch -- the characteristic magnetic field strength $b_{\rm ch}^* \sim \mathcal{o}(1)~\rm{\mu g}$ and coherent length scale $\ell_{\rm ch}^* \sim \mathcal{o}(1)~\rm{pc}$, can naturally accommodate with nanohertz gravitational waves reported by pulsar timing array collaborations. moreover, the evolution of the pmfs to the recombination era with the form of $b_{\rm ch}\sim \ell_{\rm ch}^{-\alpha}$ can induce baryon density inhomogeneities, alter the recombination history, and alleviate the tension of the hubble parameter $h_0$ and the matter clumpiness parameter $s_8$ between early and late-time measurements for $0.88\leq \alpha \leq 1.17$ (approximate 95\% credible region based on three pta likelihoods). the further evolved pmfs may account for the $\sim {\cal o}(10^{-16})$ gauss extra-galactic magnetic field inferred with grb 221009a. | primordial magnetic field as a common solution of nanohertz gravitational waves and hubble tension |
the possibility that the dark matter comprises primordial black holes (pbhs) is considered, with particular emphasis on the currently allowed mass windows at 1 016- 1 017 g , 1 020- 1 024 g and 1 - 1 03m⊙ . the planck mass relics of smaller evaporating pbhs are also considered. all relevant constraints (lensing, dynamical, large-scale structure and accretion) are reviewed and various effects necessary for a precise calculation of the pbh abundance (non-gaussianity, nonsphericity, critical collapse and merging) are accounted for. it is difficult to put all the dark matter in pbhs if their mass function is monochromatic but this is still possible if the mass function is extended, as expected in many scenarios. a novel procedure for confronting observational constraints with an extended pbh mass spectrum is therefore introduced. this applies for arbitrary constraints and a wide range of pbh formation models and allows us to identify which model-independent conclusions can be drawn from constraints over all mass ranges. we focus particularly on pbhs generated by inflation, pointing out which effects in the formation process influence the mapping from the inflationary power spectrum to the pbh mass function. we then apply our scheme to two specific inflationary models in which pbhs provide the dark matter. the possibility that the dark matter is in intermediate-mass pbhs of 1 - 1 03m⊙ is of special interest in view of the recent detection of black-hole mergers by ligo. the possibility of planck relics is also intriguing but virtually untestable. | primordial black holes as dark matter |
in response to a recent criticism, appeared in arxiv:2303.00341, we argue that the standard scenario to form primordial black holes in the early universe based on a phase of ultra-slow-roll in single-field inflation is not ruled out. | the primordial black hole formation from single-field inflation is still not ruled out |
composite topological structures such as superheavy "quasistable strings" (qss) and "walls bounded by strings" (wbs) arise in realistic extensions of the standard model of high energy physics. we show that the gravitational radiation emitted in the early universe by these two unstable structures with a dimensionless string tension g μ ≈10-6 is consistent with the nanograv evidence of low frequency gravitational background as well as the recent ligo-virgo constraints, provided the superheavy strings and monopoles experience a certain amount of inflation. for the case of walls bounded by strings, the domain walls arise from the spontaneous breaking of a remnant discrete gauge symmetry around the electroweak scale. the quasistable strings, on the other hand, arise from a two step breaking of a local gauge symmetry. the monopoles appear from the first breaking and get connected to strings that arise from the second breaking. both composite structures decay by emitting gravitational waves over a wide frequency range. the bayes factors for qss and wbs relative to the inspiraling supermassive black hole binaries are estimated to be about 60 and 30 respectively, which are comparable with that of metastable strings and cosmic superstrings. | superheavy quasistable strings and walls bounded by strings in the light of nanograv 15 year data |
the w -boson mass, which was recently measured at fermilab with an unprecedented precision, suggests the presence of new multiplets beyond the standard model (sm). one of the minimal extensions of the sm is to introduce an additional scalar doublet in which the non-sm scalars can enhance w -boson mass via the loop corrections. on the other hand, with a proper discrete symmetry, the lightest new scalar in the doublet can be stable and play the role of a dark matter particle. we show that the inert two higgs doublet model can naturally handle the new w -boson mass without violating other constraints and that the preferred dark matter mass is between 54 and 74 gev. we identify three feasible parameter regions for the thermal relic density: the s a coannihilation, the higgs resonance, and the s s →w w* annihilation. we find that the first region can be fully tested by the high luminosity large hadron collector, the second region will be tightly constrained by direct detection experiments, and the third region could yield detectable gev γ -ray and antiproton signals in the galaxy that may have been observed by the fermi large area telescope and the alpha magnetic spectrometer ams-02 experiment. | inert higgs dark matter for cdf ii w -boson mass and detection prospects |
we describe ongoing searches for intermediate-mass black holes with mbh ≈ 10-105 m⊙. we review a range of search mechanisms, both dynamical and those that rely on accretion signatures. we find the following conclusions: dynamical and accretion signatures alike point to a high fraction of 109-1010 m⊙ galaxies hosting black holes with mbh∼ 105 m⊙. in contrast, there are no solid detections of black holes in globular clusters. there are few observational constraints on black holes in any environment with mbh ≈ 100-104 m⊙. considering low-mass galaxies with dynamical black hole masses and constraining limits, we find that the mbh-σ* relation continues unbroken to mbh ∼105 m⊙, albeit with large scatter. we believe the scatter is at least partially driven by a broad range in black hole masses, because the occupation fraction appears to be relatively high in these galaxies. we fold the observed scaling relations with our empirical limits on occupation fraction and the galaxy mass function to put observational bounds on the black hole mass function in galaxy nuclei. we are pessimistic that local demographic observations of galaxy nuclei alone could constrain seeding mechanisms, although either high-redshift luminosity functions or robust measurements of off-nuclear black holes could begin to discriminate models. | intermediate-mass black holes |
recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. these ideas are best understood in anti-de sitter space, where they rely on the area law for entanglement entropy. the extension to de sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. due to the competition between area and volume law entanglement the microscopic de sitter states do not thermalise at sub-hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. the emergent laws of gravity contain an additional 'dark' gravitational force describing the 'elastic' response due to the entropy displacement. we derive an estimate of the strength of this extra force in terms of the baryonic mass, newton's constant and the hubble acceleration scale a_0 =ch_0a0=ch0, and provide evidence for the fact that this additional 'dark gravity force' explains the observed phenomena in galaxies and clusters currently attributed to dark matter. | emergent gravity and the dark universe |
using the $\delta n$ formalism we calculate the one-loop correction to the large-scale power spectrum of the curvature perturbation in the standard scenario where primordial black holes are formed in the early universe thanks to a phase of ultra-slow-roll in single-field inflation. we explicitly show that one-loop corrections are negligible when the transition from the ultra-slow-roll to the slow-roll phase is smooth. we conclude that the pbh formation scenario through a ultra-slow-roll phase is viable. | primordial black holes and loops in single-field inflation |
we present new measurements of cosmic microwave background (cmb) lensing over $9400$ sq. deg. of the sky. these lensing measurements are derived from the atacama cosmology telescope (act) data release 6 (dr6) cmb dataset, which consists of five seasons of act cmb temperature and polarization observations. we determine the amplitude of the cmb lensing power spectrum at $2.3\%$ precision ($43\sigma$ significance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. to ensure our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. the baseline spectrum is well fit by a lensing amplitude of $a_{\mathrm{lens}}=1.013\pm0.023$ relative to the planck 2018 cmb power spectra best-fit $\lambda$cdm model and $a_{\mathrm{lens}}=1.005\pm0.023$ relative to the $\text{act dr4} + \text{wmap}$ best-fit model. from our lensing power spectrum measurement, we derive constraints on the parameter combination $s^{\mathrm{cmbl}}_8 \equiv \sigma_8 \left({\omega_m}/{0.3}\right)^{0.25}$ of $s^{\mathrm{cmbl}}_8= 0.818\pm0.022$ from act dr6 cmb lensing alone and $s^{\mathrm{cmbl}}_8= 0.813\pm0.018$ when combining act dr6 and planck npipe cmb lensing power spectra. these results are in excellent agreement with $\lambda$cdm model constraints from planck or $\text{act dr4} + \text{wmap}$ cmb power spectrum measurements. our lensing measurements from redshifts $z\sim0.5$--$5$ are thus fully consistent with $\lambda$cdm structure growth predictions based on cmb anisotropies probing primarily $z\sim1100$. we find no evidence for a suppression of the amplitude of cosmic structure at low redshifts | the atacama cosmology telescope: a measurement of the dr6 cmb lensing power spectrum and its implications for structure growth |
we present the results of a first search for galaxy candidates at z ~ 9-15 on deep seven-band nircam imaging acquired as part of the glass-james webb space telescope (jwst) early release science program on a flanking field of the frontier fields cluster a2744. candidates are selected via two different renditions of the lyman-break technique, isolating objects at z ~ 9-11, and z ~ 9-15, respectively, supplemented by photometric redshifts obtained with two independent codes. we find five color-selected candidates at z > 9, plus one additional candidate with photometric redshift z phot ≥ 9. in particular, we identify two bright candidates at m uv ≃ -21 that are unambiguously placed at z ≃ 10.6 and z ≃ 12.2, respectively. the total number of galaxies discovered at z > 9 is in line with the predictions of a nonevolving luminosity function. the two bright ones at z > 10 are unexpected given the survey volume, although cosmic variance and small number statistics limits general conclusions. this first search demonstrates the unique power of jwst to discover galaxies at the high-redshift frontier. the candidates are ideal targets for spectroscopic follow-up in cycle-2. *based on observations collected with jwst under the ers program id 1324 (pi t. treu). | early results from glass-jwst. iii. galaxy candidates at z9-15 |
the pulsar timing array (pta) collaborations have recently reported compelling evidence for the presence of a stochastic signal consistent with a gravitational-wave background. in this letter, we combine the latest data sets from nanograv, ppta and epta collaborations to explore the cosmological interpretations for the detected signal from first-order phase transitions, domain walls and cosmic strings, separately. we find that the first-order phase transitions and cosmic strings can give comparable interpretations compared to supermassive black hole binaries (smbhbs) characterized by a power-law spectrum, but the domain wall model is strongly disfavored with the bayes factor compared to the smbhb model being 0.009. furthermore, the constraints on the parameter spaces indicate that: 1) a strong phase transition at temperatures below the electroweak scale is favored and the bubble collisions make the dominant contribution to the energy density spectrum; 2) the cosmic string tension is $g \mu \in [1.46, 15.3]\times 10^{-12}$ at $90\%$ confidence interval and a small reconnection probability $p<6.68\times 10^{-2}$ is preferred at $95\%$ confidence level, implying that the strings in (super)string theory are strongly favored over the classical field strings. | cosmological interpretation for the stochastic signal in pulsar timing arrays |
the cosmological principle (cp)-the notion that the universe is spatially isotropic and homogeneous on large scales-underlies a century of progress in cosmology. it is conventionally formulated through the friedmann-lemaître-robertson-walker (flrw) cosmologies as the spacetime metric, and culminates in the successful and highly predictive λ-cold-dark-matter (λcdm) model. yet, tensions have emerged within the λcdm model, most notably a statistically significant discrepancy in the value of the hubble constant, h 0. since the notion of cosmic expansion determined by a single parameter is intimately tied to the cp, implications of the h 0 tension may extend beyond λcdm to the cp itself. this review surveys current observational hints for deviations from the expectations of the cp, highlighting synergies and disagreements that warrant further study. setting aside the debate about individual large structures, potential deviations from the cp include variations of cosmological parameters on the sky, discrepancies in the cosmic dipoles, and mysterious alignments in quasar polarizations and galaxy spins. while it is possible that a host of observational systematics are impacting results, it is equally plausible that precision cosmology may have outgrown the flrw paradigm, an extremely pragmatic but non-fundamental symmetry assumption. | is the observable universe consistent with the cosmological principle? |
the nobel prize winning confirmation in 1998 of the accelerated expansion of our universe put into sharp focus the need of a consistent theoretical model to explain the origin of this acceleration. as a result over the past two decades there has been a huge theoretical and observational effort into improving our understanding of the universe. the cosmological equations describing the dynamics of a homogeneous and isotropic universe are systems of ordinary differential equations, and one of the most elegant ways these can be investigated is by casting them into the form of dynamical systems. this allows the use of powerful analytical and numerical methods to gain a quantitative understanding of the cosmological dynamics derived by the models under study. in this review we apply these techniques to cosmology. we begin with a brief introduction to dynamical systems, fixed points, linear stability theory, lyapunov stability, centre manifold theory and more advanced topics relating to the global structure of the solutions. using this machinery we then analyse a large number of cosmological models and show how the stability conditions allow them to be tightly constrained and even ruled out on purely theoretical grounds. we are also able to identify those models which deserve further in depth investigation through comparison with observational data. this review is a comprehensive and detailed study of dynamical systems applications to cosmological models focusing on the late-time behaviour of our universe, and in particular on its accelerated expansion. in self contained sections we present a large number of models ranging from canonical and non-canonical scalar fields, interacting models and non-scalar field models through to modified gravity scenarios. selected models are discussed in detail and interpreted in the context of late-time cosmology. | dynamical systems applied to cosmology: dark energy and modified gravity |
early jwst observations have uncovered a new, substantial population of red sources that might represent a previously overlooked phase of actively growing supermassive black holes (kocevski et al. 2023, matthee et al. 2023, labbe et al. 2023). one of the most intriguing examples is an extremely red, point-like object that was found to be triply-imaged by the strong lensing galaxy cluster abell 2744 (furtak et al. 2023), allowing an unprecedented detailed look into this enigmatic population. here we present deep spectroscopic jwst/nirspec observations of this object, abell2744-qso1. the spectroscopy confirms that the three images are of the same object, and that it is a highly reddened ($a_v\sim3$) broad emission-line active galactic nucleus (agn) at a redshift of $z_{\mathrm{spec}}=7.0451\pm0.0005$. from the width of h$\beta$ ($\mathrm{fwhm}=2800\pm250\,\frac{\mathrm{km}}{\mathrm{s}}$) we derive a black hole mass of $m_{\mathrm{bh}}=3_{-1}^{+2}\times10^7\,\mathrm{m}_{\odot}$. we infer a very high ratio of black hole to galaxy mass of at least 3% and possibly as high as 100%, an order of magnitude or more than is seen in local galaxies. the lack of strong metal lines in the spectrum together with the high bolometric luminosity ($l_{\mathrm{bol}}=(1.1\pm0.3)\times10^{45}\,\frac{\mathrm{erg}}{\mathrm{s}}$) suggest that we are seeing the black hole in a phase of rapid growth, accreting at 30% of the eddington limit. based on early jwst imaging studies we estimate that such heavily reddened, low-mass black holes can be $\sim100$ times more common than uv-selected ones at this epoch. the rapid growth and high black hole to galaxy mass ratio of a2744-qso1 suggests that it may represent the missing link between black hole seeds (inayoshi et al. 2020; greene et al. 2020; volonteri 2021) and the first luminous quasars (fan et al. 2023). | a supermassive black hole in the early universe growing in the shadows |
we present constraints on weakly interacting massive particles (wimp)-nucleus scattering from the 2013 data of the large underground xenon dark matter experiment, including 1.4 ×104 kg day of search exposure. this new analysis incorporates several advances: single-photon calibration at the scintillation wavelength, improved event-reconstruction algorithms, a revised background model including events originating on the detector walls in an enlarged fiducial volume, and new calibrations from decays of an injected tritium β source and from kinematically constrained nuclear recoils down to 1.1 kev. sensitivity, especially to low-mass wimps, is enhanced compared to our previous results which modeled the signal only above a 3 kev minimum energy. under standard dark matter halo assumptions and in the mass range above 4 gev c-2 , these new results give the most stringent direct limits on the spin-independent wimp-nucleon cross section. the 90% c.l. upper limit has a minimum of 0.6 zb at 33 gev c-2 wimp mass. | improved limits on scattering of weakly interacting massive particles from reanalysis of 2013 lux data |
we study the imprint of new particles on the primordial cosmological fluctuations. new particles with masses comparable to the hubble scale produce a distinctive signature on the non-gaussianities. this feature arises in the squeezed limit of the correlation functions of primordial fluctuations. it consists of particular power law, or oscillatory, behavior that contains information about the masses of new particles. there is an angular dependence that gives information about the spin. we also have a relative phase that crucially depends on the quantum mechanical nature of the fluctuations and can be viewed as arising from the interference between two processes. while some of these features were noted before in the context of specific inflationary scenarios, here we give a general description emphasizing the role of symmetries in determining the final result. | cosmological collider physics |
this paper presents the planck 2015 likelihoods, statistical descriptions of the 2-point correlationfunctions of the cosmic microwave background (cmb) temperature and polarization fluctuations that account for relevant uncertainties, both instrumental and astrophysical in nature. they are based on the same hybrid approach used for the previous release, i.e., a pixel-based likelihood at low multipoles (ℓ< 30) and a gaussian approximation to the distribution of cross-power spectra at higher multipoles. the main improvements are the use of more and better processed data and of planck polarization information, along with more detailed models of foregrounds and instrumental uncertainties. the increased redundancy brought by more than doubling the amount of data analysed enables further consistency checks and enhanced immunity to systematic effects. it also improves the constraining power of planck, in particular with regard to small-scale foreground properties. progress in the modelling of foreground emission enables the retention of a larger fraction of the sky to determine the properties of the cmb, which also contributes to the enhanced precision of the spectra. improvements in data processing and instrumental modelling further reduce uncertainties. extensive tests establish the robustness and accuracy of the likelihood results, from temperature alone, from polarization alone, and from their combination. for temperature, we also perform a full likelihood analysis of realistic end-to-end simulations of the instrumental response to the sky, which were fed into the actual data processing pipeline; this does not reveal biases from residual low-level instrumental systematics. even with the increase in precision and robustness, the λcdm cosmological model continues to offer a very good fit to the planck data. the slope of the primordial scalar fluctuations, ns, is confirmed smaller than unity at more than 5σ from planck alone. we further validate the robustness of the likelihood results against specific extensions to the baseline cosmology, which are particularly sensitive to data at high multipoles. for instance, the effective number of neutrino species remains compatible with the canonical value of 3.046. for this first detailed analysis of planck polarization spectra, we concentrate at high multipoles on the e modes, leaving the analysis of the weaker b modes to future work. at low multipoles we use temperature maps at all planck frequencies along with a subset of polarization data. these data take advantage of planck's wide frequency coverage to improve the separation of cmb and foreground emission. within the baseline λcdm cosmology this requires τ = 0.078 ± 0.019 for the reionization optical depth, which is significantly lower than estimates without the use of high-frequency data for explicit monitoring of dust emission. at high multipoles we detect residual systematic errors in e polarization, typically at the μk2 level; we therefore choose to retain temperature information alone for high multipoles as the recommended baseline, in particular for testing non-minimal models. nevertheless, the high-multipole polarization spectra from planck are already good enough to enable a separate high-precision determination of the parameters of the λcdm model, showing consistency with those established independently from temperature information alone. | planck 2015 results. xi. cmb power spectra, likelihoods, and robustness of parameters |
ultra-light dark matter is a class of dark matter models (dm), where dm is composed by bosons with masses ranging from 10-24ev <m <ev . these models have been receiving a lot of attention in the past few years given their interesting property of forming a bose-einstein condensate (bec) or a superfluid on galactic scales. bec and superfluidity are some of the most striking quantum mechanical phenomena that manifest on macroscopic scales, and upon condensation, the particles behave as a single coherent state, described by the wavefunction of the condensate. the idea is that condensation takes place inside galaxies while outside, on large scales, it recovers the successes of λ cdm. this wave nature of dm on galactic scales that arise upon condensation can address some of the curiosities of the behaviour of dm on small-scales. there are many models in the literature that describe a dm component that condenses in galaxies. in this review, we are going to describe those models, and classify them into three classes, according to the different non-linear evolution and structures they form in galaxies: the fuzzy dark matter (fdm), the self-interacting fuzzy dark matter (sifdm), and the dm superfluid. each of these classes comprises many models, each presenting a similar phenomenology in galaxies. they also include some microscopic models like the axions and axion-like particles. to understand and describe this phenomenology in galaxies, we are going to review the phenomena of bec and superfluidity that arise in condensed matter physics, and apply this knowledge to dm. we describe how uldm can potentially reconcile the cold dm picture with the small-scale behaviour. these models present a rich phenomenology that is manifest in different astrophysical consequences. we review here the astrophysical and cosmological tests used to constrain those models, together with new and future observations that promise to test these models in different regimes. for the case of the fdm class, the mass where this model has an interesting phenomenology on small-scales ∼10-22ev , is strongly challenged by current observations. the parameter space for the other two classes remains weakly constrained. we finalize by showing some predictions that are a consequence of the wave nature of this component, like the creation of vortices and interference patterns, that could represent a smoking gun in the search of these rich and interesting alternative class of dm models. | ultra-light dark matter |
measurements of the hubble constant and, more generally, measurements of the expansion rate and distances over the interval 0 <z <1 appear to be inconsistent with the predictions of the standard cosmological model (λ cdm ) given observations of cosmic microwave background temperature and polarization anisotropies. here we consider a variety of types of departures from λ cdm that could, in principle, restore concordance among these datasets, and we explain why we find almost all of them unlikely to be successful. we single out the set of solutions that increases the expansion rate in the decade of scale factor expansion just prior to recombination as the least unlikely. these solutions are themselves tightly constrained by their impact on photon diffusion and on the gravitational driving of acoustic oscillations of the modes that begin oscillating during this epoch—modes that project on to angular scales that are very well measured. we point out that a general feature of such solutions is a residual to fits to λ cdm , like the one observed in planck power spectra. this residual drives the modestly significant inferences of angular-scale dependence to the matter density and anomalously high lensing power, puzzling aspects of a dataset that is otherwise extremely well fit by λ cdm . | hubble constant hunter's guide |
the evidence of the nano-hertz stochastic gravitational wave (gw) background is reported by multiple pulsar timing array collaborations. while a prominent candidate of the origin is astrophysical from supermassive black hole binaries, alternative models involving gws induced by primordial curvature perturbations can explain the inferred gw spectrum. serendipitously, the nano-hertz range coincides with the hubble scale during the cosmological quantum chromodynamics (qcd) phase transition. the influence of the qcd phase transition can modify the spectrum of induced gws within the nano-hertz frequency range, necessitating careful analysis. we estimate gws induced by power-law power spectra of primordial curvature perturbations taking account of the qcd phase transition. then we translate the implication of the nanograv data into the constraint on the power spectrum of the primordial curvature perturbation, which suggests one would underestimate the amplitude by about 25% and the spectral index by up to 10% if neglecting the qcd effect. | translating nano-hertz gravitational wave background into primordial perturbations taking account of the cosmological qcd phase transition |
recent years have witnessed a rise in interest in the geometrical trinity of general relativity and its extensions. this interest has been fuelled by novel insights into the nature of gravity, the possibility to address computational and conceptual questions -- such as the determination of black hole entropy or the definition of gravitational energy-momentum -- from a new perspective. in particular, $f(q)$ gravity has also inspired numerous works on black holes, wormholes, and cosmology. in the latter case, $f(q)$ models have the potential to elucidate phenomena in both early and late-time cosmology without necessitating the inclusion of dark energy, the inflaton field, or dark matter. particularly noteworthy is the role of $f(q)$ theories in addressing cosmological tensions, presenting exciting possibilities for reshaping our understanding of gravity and its manifestations in cosmology. the emergence of intriguing new black hole solutions and the potential existence of wormhole solutions suggest the presence of novel physics within the realm of strong gravity. these phenomena have become increasingly measurable only in recent times, opening up exciting avenues for further exploration and discovery. this review is tailored to students and researchers alike. it offers a self-contained and pedagogical introduction to metric-affine geometry--the mathematical foundation and indispensable tool upon which the geometrical trinity of general relativity as well as its various extensions are built. | review on $f(q)$ gravity |
aims: we describe the photometric content of the second data release of the gaia project (gaia dr2) and its validation along with the quality of the data.methods: the validation was mainly carried out using an internal analysis of the photometry. external comparisons were also made, but were limited by the precision and systematics that may be present in the external catalogues used.results: in addition to the photometric quality assessment, we present the best estimates of the three photometric passbands. various colour-colour transformations are also derived to enable the users to convert between the gaia and commonly used passbands.conclusions: the internal analysis of the data shows that the photometric calibrations can reach a precision as low as 2 mmag on individual ccd measurements. other tests show that systematic effects are present in the data at the 10 mmag level. | gaia data release 2. photometric content and validation |
we propose a new model-independent mechanism for producing primordial black holes from a period of multi-field inflation. this requires an enhancement of primordial fluctuations at short scales compared to their value at cmb scales. we show that such an amplification naturally occurs when the inflationary trajectory exhibits a strong turn, that is a limited period during which the trajectory strongly deviates from a geodesic in field space, and is sufficient for subsequently producing primordial black holes with the abundance to be all or a fraction of dark matter. our mechanism is generic to models of inflation realized in a multi-dimensional field space with an overlying potential and geometry, also referred to as the inflationary landscape, as arises in embeddings of inflation in high-energy theories. we study analytically and numerically how the duration and the strength of the turn impact the primordial fluctuation power spectrum and the abundance of primordial black holes. our mechanism has the potential of exhibiting unique features accessible to observation through the primordial black hole spectrum and the stochastic background of gravitational waves, offering a precious glimpse at the dynamics of inflation. | turning in the landscape: a new mechanism for generating primordial black holes |
the large synoptic survey telescope (lsst) dark energy science collaboration (desc) will use five cosmological probes: galaxy clusters, large scale structure, supernovae, strong lensing, and weak lensing. this science requirements document (srd) quantifies the expected dark energy constraining power of these probes individually and together, with conservative assumptions about analysis methodology and follow-up observational resources based on our current understanding and the expected evolution within the field in the coming years. we then define requirements on analysis pipelines that will enable us to achieve our goal of carrying out a dark energy analysis consistent with the dark energy task force definition of a stage iv dark energy experiment. this is achieved through a forecasting process that incorporates the flowdown to detailed requirements on multiple sources of systematic uncertainty. future versions of this document will include evolution in our software capabilities and analysis plans along with updates to the lsst survey strategy. | the lsst dark energy science collaboration (desc) science requirements document |
gravitational waves (gws) have a great potential to probe cosmology. we review early universe sources that can lead to cosmological backgrounds of gws. we begin by presenting proper definitions of gws in flat space-time and in a cosmological setting (section 2). following, we discuss the reasons why early universe gw backgrounds are of a stochastic nature, and describe the general properties of a stochastic background (section 3). we recap current observational constraints on stochastic backgrounds, and discuss the basic characteristics of present and future gw detectors, including advanced ligo, advanced virgo, the einstein telescope, kagra, and lisa (section 4). we then review in detail early universe gw generation mechanisms, as well as the properties of the gw backgrounds they give rise to. we classify the backgrounds in five categories: gws from quantum vacuum fluctuations during standard slow-roll inflation (section 5), gws from processes that operate within extensions of the standard inflationary paradigm (section 6), gws from post-inflationary preheating and related non-perturbative phenomena (section 7), gws from first order phase transitions related or not to the electroweak symmetry breaking (section 8), and gws from general topological defects, and from cosmic strings in particular (section 9). the phenomenology of these early universe processes is extremely rich, and some of the gw backgrounds they generate can be within the reach of near-future gw detectors. a future detection of any of these backgrounds will provide crucial information on the underlying high energy theory describing the early universe, probing energy scales well beyond the reach of particle accelerators. | cosmological backgrounds of gravitational waves |
axions are well-motivated dark matter candidates with simple cosmological production mechanisms. they were originally introduced to solve the strong cp problem, but also arise in a wide range of extensions to the standard model. this snowmass white paper summarizes axion phenomenology and outlines next-generation laboratory experiments proposed to detect axion dark matter. there are vibrant synergies with astrophysical searches and advances in instrumentation including quantum-enabled readout, high-q resonators and cavities and large high-field magnets. this white paper outlines a clear roadmap to discovery, and shows that the us is well-positioned to be at the forefront of the search for axion dark matter in the coming decade. | axion dark matter |
the laser interferometer space antenna (lisa) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the mev to the planck scale. however, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. this publication presents a summary of the state of the art in lisa cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by lisa to probe the universe. | cosmology with the laser interferometer space antenna |
primordial nucleosynthesis is one of the three historical evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. there is a good global agreement between the computed primordial abundances of helium-4, deuterium, helium-3 and their values deduced from observations. now that the number of neutrino families and the baryonic densities have been fixed by laboratory measurements or cmb observations, the model has no free parameter and its predictions are rigid. since this is the earliest cosmic process for which we a priori know all the physics involved, departure from its predictions could provide hints or constraints on new physics or astrophysics in the early universe. precision on primordial abundances deduced from observations has recently been drastically improved and reach the percent level for both deuterium and helium-4. accordingly, the bbn predictions should reach the same level of precision. for most isotopes, the dominant sources of uncertainty come from those on the laboratory thermonuclear reactions. this article focuses on helium-4 whose predicted primordial abundance depends essentially on weak interactions which control the neutron-proton ratio. the rates of the various weak interaction processes depend on the experimentally measured neutron lifetime, but also includes numerous corrections that we thoroughly investigate here. they are the radiative, zero-temperature, corrections, finite nucleon mass corrections, finite temperature radiative corrections, weak-magnetism, and qed plasma effects, which are for the first time all included and calculated in a self consistent way, allowing to take into account the correlations between them, and verifying that all satisfy detailed balance. finally, we include the incomplete neutrino decoupling and claim to reach a 10-4 accuracy on the helium-4 predicted mass fraction of 0 . 24709 ± 0 . 00017 (when including the uncertainty on the neutron lifetime). in addition, we provide a mathematica primordial nucleosynthesis code that incorporates, not only these corrections but also a full network of reactions, using the best available thermonuclear reaction rates, allowing the predictions of primordial abundances of helium-4, deuterium, helium-3 and lithium-7 but also of heavier isotopes up to the cno region. | precision big bang nucleosynthesis with improved helium-4 predictions |
this article reviews current understanding of primordial black holes (pbhs), with particular focus on those massive examples (≳ 1015~g ) which remain at the present epoch, not having evaporated through hawking radiation. with the detection of gravitational waves by ligo, we have gained a completely novel observational tool to search for pbhs, complementary to those using electromagnetic waves. taking the perspective that gravitational-wave astronomy will make significant progress in the coming decades, the purpose of this article is to give a comprehensive review covering a wide range of topics on pbhs. after discussing pbh formation, as well as several inflation models leading to pbh production, we summarize various existing and future observational constraints. we then present topics on formation of pbh binaries, gravitational waves from pbh binaries, and various observational tests of pbhs using gravitational waves. | primordial black holes—perspectives in gravitational wave astronomy |
we review the status of bouncing cosmologies as alternatives to cosmological inflation for providing a description of the very early universe, and a source for the cosmological perturbations which are observed today. we focus on the motivation for considering bouncing cosmologies, the origin of fluctuations in these models, and the challenges which various implementations face. | bouncing cosmologies: progress and problems |
we report results of a search for an isotropic gravitational-wave background (gwb) using data from advanced ligo's and advanced virgo's third observing run (o3) combined with upper limits from the earlier o1 and o2 runs. unlike in previous observing runs in the advanced detector era, we include virgo in the search for the gwb. the results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the gwb. we find that the dimensionless energy density ωgw≤5.8 ×10-9 at the 95% credible level for a flat (frequency-independent) gwb, using a prior which is uniform in the log of the strength of the gwb, with 99% of the sensitivity coming from the band 20-76.6 hz; ωgw(f )≤3.4 ×10-9 at 25 hz for a power-law gwb with a spectral index of 2 /3 (consistent with expectations for compact binary coalescences), in the band 20-90.6 hz; and ωgw(f )≤3.9 ×10-10 at 25 hz for a spectral index of 3, in the band 20-291.6 hz. these upper limits improve over our previous results by a factor of 6.0 for a flat gwb, 8.8 for a spectral index of 2 /3 , and 13.1 for a spectral index of 3. we also search for a gwb arising from scalar and vector modes, which are predicted by alternative theories of gravity; we do not find evidence of these, and place upper limits on the strength of gwbs with these polarizations. we demonstrate that there is no evidence of correlated noise of magnetic origin by performing a bayesian analysis that allows for the presence of both a gwb and an effective magnetic background arising from geophysical schumann resonances. we compare our upper limits to a fiducial model for the gwb from the merger of compact binaries, updating the model to use the most recent data-driven population inference from the systems detected during o3a. finally, we combine our results with observations of individual mergers and show that, at design sensitivity, this joint approach may yield stronger constraints on the merger rate of binary black holes at z ≳2 than can be achieved with individually resolved mergers alone. | upper limits on the isotropic gravitational-wave background from advanced ligo and advanced virgo's third observing run |
we present an incremental version (4fgl-dr3, for data release 3) of the fourth fermi large area telescope (lat) catalog of γ-ray sources. based on the first 12 years of science data in the energy range from 50 mev to 1 tev, it contains 6658 sources. the analysis improves on that used for the 4fgl catalog over eight years of data: more sources are fit with curved spectra, we introduce a more robust spectral parameterization for pulsars, and we extend the spectral points to 1 tev. the spectral parameters, spectral energy distributions, and associations are updated for all sources. light curves are rebuilt for all sources with 1 yr intervals (not 2 month intervals). among the 5064 original 4fgl sources, 16 were deleted, 112 are formally below the detection threshold over 12 yr (but are kept in the list), while 74 are newly associated, 10 have an improved association, and seven associations were withdrawn. pulsars are split explicitly between young and millisecond pulsars. pulsars and binaries newly detected in lat sources, as well as more than 100 newly classified blazars, are reported. we add three extended sources and 1607 new point sources, mostly just above the detection threshold, among which eight are considered identified, and 699 have a plausible counterpart at other wavelengths. we discuss the degree-scale residuals to the global sky model and clusters of soft unassociated point sources close to the galactic plane, which are possibly related to limitations of the interstellar emission model and missing extended sources. | incremental fermi large area telescope fourth source catalog |
in this letter we present a general covariant modified theory of gravity in d =4 spacetime dimensions which propagates only the massless graviton and bypasses lovelock's theorem. the theory we present is formulated in d >4 dimensions and its action consists of the einstein-hilbert term with a cosmological constant, and the gauss-bonnet term multiplied by a factor 1 /(d -4 ). the four-dimensional theory is defined as the limit d →4 . in this singular limit the gauss-bonnet invariant gives rise to nontrivial contributions to gravitational dynamics, while preserving the number of graviton degrees of freedom and being free from ostrogradsky instability. we report several appealing new predictions of this theory, including the corrections to the dispersion relation of cosmological tensor and scalar modes, singularity resolution for spherically symmetric solutions, and others. | einstein-gauss-bonnet gravity in four-dimensional spacetime |
we discuss the issue of perturbativity in single-field inflationary models with a phase of ultra slow-roll (usr) tailor suited to generate an order-one abundance of primordial black holes (pbhs). more in detail, we impose the condition that loop corrections made up of short-wavelength modes enhanced by the usr dynamics do not alter the tree-level power spectrum of curvature perturbations. in our analysis, the usr phase is preceded and followed by two stages of ordinary slow-roll (sr), and we model the resulting sr/usr/sr dynamics using both instantaneous and smooth transitions. focusing on scales relevant for cmb observations, we find that it is not possible, with these arguments, to rule out the scenario of pbh formation via usr, not even in the limit of instantaneous transition. however, we also find that loop corrections of short modes on the power spectrum of long modes, even though not large enough to violate perturbativity requirements, remain appreciable and, most importantly, are not tamed in realistic realisations of smooth sr/usr/sr transitions. this makes perturbativity a powerful theoretical tool to constrain usr dynamics. we extend the analysis at any scale beyond those relevant for cmb observations. we find that loop corrections of short modes remain within the few percent if compared to the tree-level power spectrum. however, we also find one notable exception of phenomenological relevance: we show that the so-called dip in the power spectrum of curvature perturbation is an artifact of the tree-level computation. | one loop to rule them all: perturbativity in the presence of ultra slow-roll dynamics |
we perform a bayesian analysis of nanograv 15-yr and ipta dr2 pulsar timing residuals and show that the recently detected stochastic gravitational-wave background is compatible with a stochastic gravitational-wave background produced by bubble dynamics during a cosmological first-order phase transition. the timing data suggest that the phase transition would occur around qcd confinement temperature and would have a slow rate of completion. this scenario can naturally lead to the abundant production of primordial black holes with solar masses. these primordial black holes can potentially be detected by current and advanced gravitational-wave detectors ligo-virgo-kagra, einstein telescope, cosmic explorer, by astrometry with gaia, and by 21-cm survey. | first-order phase transition interpretation of pulsar timing array signal is consistent with solar-mass black holes |
the nuclei of most normal galaxies contain supermassive black holes, which can accrete gas through a disk and become active. these active galactic nuclei (agns) can form jets that are observed on scales from astronomical units to megaparsecs and from meter wavelengths to tev energies. high-resolution radio imaging and multiwavelength/messenger campaigns are elucidating the conditions under which this happens. evidence is presented that: relativistic agn jets are formed when the black hole spins and the the accretion disk is strongly magnetized, perhaps on account of gas accreting at high latitude beyond the black hole sphere of influence. agn jets are collimated close to the black hole by magnetic stress associated with a disk wind. higher-power jets can emerge from their galactic nuclei in a relativistic, supersonic, and proton-dominated state, and they terminate in strong, hot spot shocks; lower-power jets are degraded to buoyant plumes and bubbles. jets may accelerate protons to eev energies, which contribute to the cosmic ray spectrum and may initiate pair cascades that can efficiently radiate synchrotron γ-rays. jets were far more common when the universe was a few billion years old and black holes and massive galaxies were growing rapidly. jets can have a major influence on their environments, stimulating and limiting the growth of galaxies.the observational prospects for securing our understanding of agn jets are bright. | relativistic jets from active galactic nuclei |
the cresst-ii experiment uses cryogenic detectors to search for nuclear recoil events induced by the elastic scattering of dark matter particles in cawo_4 crystals. given the low energy threshold of our detectors in combination with light target nuclei, low mass dark matter particles can be probed with high sensitivity. in this letter we present the results from data of a single detector module corresponding to 52 kg live days. a blind analysis is carried out. with an energy threshold for nuclear recoils of 307 ev we substantially enhance the sensitivity for light dark matter. thereby, we extend the reach of direct dark matter experiments to the sub- gev/c^2 region and demonstrate that the energy threshold is the key parameter in the search for low mass dark matter particles. | results on light dark matter particles with a low-threshold cresst-ii detector |
<related-article ext-link-type="doi" related-article-type="companion" xlink:href="10.1103/physrevd.105.023515"/>this work, together with its companion paper, secco, samuroff et al. [phys. rev. d 105, 023515 (2022), 10.1103/physrevd.105.023515], present the dark energy survey year 3 cosmic-shear measurements and cosmological constraints based on an analysis of over 100 million source galaxies. with the data spanning 4143 deg2 on the sky, divided into four redshift bins, we produce a measurement with a signal-to-noise of 40. we conduct a blind analysis in the context of the lambda-cold dark matter (λ cdm ) model and find a 3% constraint of the clustering amplitude, s8≡σ8(ωm/0.3 )0.5=0.75 9-0.023+0.025. a λ cdm -optimized analysis, which safely includes smaller scale information, yields a 2% precision measurement of s8=0.77 2-0.017+0.018 that is consistent with the fiducial case. the two low-redshift measurements are statistically consistent with the planck cosmic microwave background result, however, both recovered s8 values are lower than the high-redshift prediction by 2.3 σ and 2.1 σ (p -values of 0.02 and 0.05), respectively. the measurements are shown to be internally consistent across redshift bins, angular scales and correlation functions. the analysis is demonstrated to be robust to calibration systematics, with the s8 posterior consistent when varying the choice of redshift calibration sample, the modeling of redshift uncertainty and methodology. similarly, we find that the corrections included to account for the blending of galaxies shifts our best-fit s8 by 0.5 σ without incurring a substantial increase in uncertainty. we examine the limiting factors for the precision of the cosmological constraints and find observational systematics to be subdominant to the modeling of astrophysics. specifically, we identify the uncertainties in modeling baryonic effects and intrinsic alignments as the limiting systematics. | dark energy survey year 3 results: cosmology from cosmic shear and robustness to data calibration |
a nanohertz-frequency stochastic gravitational-wave background can potentially be detected through the precise timing of an array of millisecond pulsars. this background produces low-frequency noise in the pulse arrival times that would have a characteristic spectrum common to all pulsars and a well-defined spatial correlation. recently the north american nanohertz observatory for gravitational waves collaboration (nanograv) found evidence for the common-spectrum component in their 12.5 yr data set. here we report on a search for the background using the second data release of the parkes pulsar timing array. if we are forced to choose between the two nanograv models-one with a common-spectrum process and one without-we find strong support for the common-spectrum process. however, in this paper, we consider the possibility that the analysis suffers from model misspecification. in particular, we present simulated data sets that contain noise with distinctive spectra but show strong evidence for a common-spectrum process under the standard assumptions. the parkes data show no significant evidence for, or against, the spatially correlated hellings-downs signature of the gravitational-wave background. assuming we did observe the process underlying the spatially uncorrelated component of the background, we infer its amplitude to be $a={2.2}_{-0.3}^{+0.4}\times {10}^{-15}$ in units of gravitational-wave strain at a frequency of 1 yr-1. extensions and combinations of existing and new data sets will improve the prospects of identifying spatial correlations that are necessary to claim a detection of the gravitational-wave background. | on the evidence for a common-spectrum process in the search for the nanohertz gravitational-wave background with the parkes pulsar timing array |
we report the results of a joint analysis of data from bicep2/keck array and planck. bicep2 and keck array have observed the same approximately 400 deg2 patch of sky centered on ra 0 h, dec. -57.5 ° . the combined maps reach a depth of 57 nk deg in stokes q and u in a band centered at 150 ghz. planck has observed the full sky in polarization at seven frequencies from 30 to 353 ghz, but much less deeply in any given region (1.2 μ k deg in q and u at 143 ghz). we detect 150 ×353 cross-correlation in b modes at high significance. we fit the single- and cross-frequency power spectra at frequencies ≥150 ghz to a lensed-λ cdm model that includes dust and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r), using a prior on the frequency spectral behavior of polarized dust emission from previous planck analysis of other regions of the sky. we find strong evidence for dust and no statistically significant evidence for tensor modes. we probe various model variations and extensions, including adding a synchrotron component in combination with lower frequency data, and find that these make little difference to the r constraint. finally, we present an alternative analysis which is similar to a map-based cleaning of the dust contribution, and show that this gives similar constraints. the final result is expressed as a likelihood curve for r, and yields an upper limit r0.05<0.12 at 95% confidence. marginalizing over dust and r, lensing b modes are detected at 7.0 σ significance. | joint analysis of bicep2/keck array and planck data |
this review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. we focus on large scales where cosmic density fields are quasi-linear. on these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. the review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of general relativity and gaussian, adiabatic initial conditions. key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. we hence expand the definition of local bias to encompass all these contributions. this derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy statistics. we then review the excursion-set formalism and peak theory which provide predictions for the values of the bias parameters. in the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, gaussian initial conditions: primordial non-gaussianity, massive neutrinos, baryon-cdm isocurvature perturbations, dark energy, and modified gravity. finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs. | large-scale galaxy bias |
using the effective field theory (eft) framework of single field inflation, we investigate the possibility of the formation of primordial black holes (pbhs) in the slow roll (sr) to ultra slow roll (usr) sharp transition. we demonstrate that, due to one-loop correction to the power spectrum, causality is violated (cs > 1) for the mass range of pbhs, mpbh >102 gm created during the said transition. we find that non-canonical features with cs < 1 worsen the predictions of the canonical framework of single-field inflation. | pbh formation in eft of single field inflation with sharp transition |
we study the implications of planck data for models of dark energy (de) and modified gravity (mg) beyond the standard cosmological constant scenario. we start with cases where the de only directly affects the background evolution, considering taylor expansions of the equation of state w(a), as well as principal component analysis and parameterizations related to the potential of a minimally coupled de scalar field. when estimating the density of de at early times, we significantly improve present constraints and find that it has to be below ~2% (at 95% confidence) of the critical density, even when forced to play a role for z < 50 only. we then move to general parameterizations of the de or mg perturbations that encompass both effective field theories and the phenomenology of gravitational potentials in mg models. lastly, we test a range of specific models, such as k-essence, f(r) theories, and coupled de. in addition to the latest planck data, for our main analyses, we use background constraints from baryonic acoustic oscillations, type-ia supernovae, and local measurements of the hubble constant. we further show the impact of measurements of the cosmological perturbations, such as redshift-space distortions and weak gravitational lensing. these additional probes are important tools for testing mg models and for breaking degeneracies that are still present in the combination of planck and background data sets. all results that include only background parameterizations (expansion of the equation of state, early de, general potentials in minimally-coupled scalar fields or principal component analysis) are in agreement with λcdm. when testing models that also change perturbations (even when the background is fixed to λcdm), some tensions appear in a few scenarios: the maximum one found is ~2σ for planck tt+lowp when parameterizing observables related to the gravitational potentials with a chosen time dependence; the tension increases to, at most, 3σ when external data sets are included. it however disappears when including cmb lensing. | planck 2015 results. xiv. dark energy and modified gravity |
predicting structural properties of dark matter haloes is one of the fundamental goals of modern cosmology. we use the suite of multidark cosmological simulations to study the evolution of dark matter halo density profiles, concentrations, and velocity anisotropies. we find that in order to understand the structure of dark matter haloes and to make 1-2 per cent accurate predictions for density profiles, one needs to realize that halo concentration is more complex than the ratio of the virial radius to the core radius in the navarro-frenk-white (nfw) profile. for massive haloes, the average density profile is far from the nfw shape and the concentration is defined by both the core radius and the shape parameter α in the einasto approximation. we show that haloes progress through three stages of evolution. they start as rare density peaks and experience fast and nearly radial infall that brings mass closer to the centre, producing a highly concentrated halo. here, the halo concentration increases with increasing halo mass and the concentration is defined by the α parameter with a nearly constant core radius. later haloes slide into the plateau regime where the accretion becomes less radial, but frequent mergers still affect even the central region. at this stage, the concentration does not depend on halo mass. once the rate of accretion and merging slows down, haloes move into the domain of declining concentration-mass relation because new accretion piles up mass close to the virial radius while the core radius is staying constant. accurate analytical fits are provided. | multidark simulations: the story of dark matter halo concentrations and density profiles |
here we present 1701 light curves of 1550 unique, spectroscopically confirmed type ia supernovae (sne ia) that will be used to infer cosmological parameters as part of the pantheon+ sn analysis and the supernovae and h 0 for the equation of state of dark energy distance-ladder analysis. this effort is one part of a series of works that perform an extensive review of redshifts, peculiar velocities, photometric calibration, and intrinsic-scatter models of sne ia. the total number of light curves, which are compiled across 18 different surveys, is a significant increase from the first pantheon analysis (1048 sne), particularly at low redshift (z). furthermore, unlike in the pantheon analysis, we include light curves for sne with z < 0.01 such that sn systematic covariance can be included in a joint measurement of the hubble constant (h 0) and the dark energy equation-of-state parameter (w). we use the large sample to compare properties of 151 sne ia observed by multiple surveys and 12 pairs/triplets of "sn siblings"-sne found in the same host galaxy. distance measurements, application of bias corrections, and inference of cosmological parameters are discussed in the companion paper by brout et al., and the determination of h 0 is discussed by riess et al. these analyses will measure w with ~3% precision and h 0 with ~1 km s-1 mpc-1 precision. | the pantheon+ analysis: the full data set and light-curve release |
recent observations have granted to us two unique insights into the early universe: the presence of a low-frequency stochastic gravitational wave background detected by the nanograv and pulsar timing array (pta) experiments and the emergence of unusually massive galaxy candidates at high redshifts reported by the james webb space telescope (jwst). in this letter, we consider the possibility that both observations have a common origin, namely primordial black holes (pbhs) in the mass range between $10^{6}~m_{\odot}$ and $10^{13}~m_{\odot}$. while superheavy pbhs act as seeds of accelerated galaxy formation capable of explaining the jwst extreme galaxies, they can also form binary mergers that source gravitational waves which can be potentially identified as the pta signal. the analysis is performed taking into account the constraints on the relevant region of the pbh parameter space including the novel bound imposed by the so-called ultraviolet luminosity function of galaxies observed by the hubble space telescope. we conclude that pta's and jwst's interpretations in terms of pbh binary mergers and poissonian gas of pbhs, respectively, are strongly excluded. | scrutinizing the primordial black holes interpretation of pta gravitational waves and jwst early galaxies |
we point out that the gravitational-wave event gw150914 observed by the ligo detectors can be explained by the coalescence of primordial black holes (pbhs). it is found that the expected pbh merger rate would exceed the rate estimated by the ligo scientific collaboration and the virgo collaboration if pbhs were the dominant component of dark matter, while it can be made compatible if pbhs constitute a fraction of dark matter. intriguingly, the abundance of pbhs required to explain the suggested lower bound on the event rate, >2 events gpc-3 yr-1 , roughly coincides with the existing upper limit set by the nondetection of the cosmic microwave background spectral distortion. this implies that the proposed pbh scenario may be tested in the not-too-distant future. | primordial black hole scenario for the gravitational-wave event gw150914 |
context. the third gaia data release is published in two stages. the early part, gaia edr3, gives very precise astrometric and photometric properties for nearly two billion sources together with seven million radial velocities from gaia dr2. the full release, gaia dr3, will add radial velocities, spectra, light curves, and astrophysical parameters for a large subset of the sources, as well as orbits for solar system objects.aims: before the publication of the catalogue, many different data items have undergone dedicated validation processes. the goal of this paper is to describe the validation results in terms of completeness, accuracy, and precision for the gaia edr3 data and to provide recommendations for the use of the catalogue data.methods: the validation processes include a systematic analysis of the catalogue contents to detect anomalies, either individual errors or statistical properties, using statistical analysis and comparisons to the previous release as well as to external data and to models.results: gaia edr3 represents a major step forward, compared to gaia dr2, in terms of precision, accuracy, and completeness for both astrometry and photometry. we provide recommendations for dealing with issues related to the parallax zero point, negative parallaxes, photometry for faint sources, and the quality indicators. | gaia early data release 3. catalogue validation |
we study in detail sub-gev dark matter scattering off electrons in xenon, including the expected electron recoil spectra and annual modulation spectra. we derive improved constraints using low-energy xenon10 and xenon100 ionization-only data. for xenon10, in addition to including electron-recoil data corresponding to about 1-3 electrons, we include for the first time events corresponding to about 4-7 electrons. assuming the scattering is momentum independent (fdm=1 ), this strengthens a previous cross-section bound by almost an order of magnitude for dark matter masses above 50 mev. the available xenon100 data corresponds to events with about 4-50 electrons, and leads to a constraint that is comparable to the xenon10 bound above 50 mev for fdm=1 . we demonstrate that a search for an annual modulation signal in upcoming xenon experiments (xenon1t, xenonnt, lz) could substantially improve the above bounds even in the presence of large backgrounds. we also emphasize that in simple benchmark models of sub-gev dark matter, the dark matter-electron scattering rate can be as high as one event every ten (two) seconds in the xenon1t (xenonnt or lz) experiments, without being in conflict with any other known experimental bounds. while there are several sources of backgrounds that can produce single- or few-electron events, a large event rate can be consistent with a dark matter signal and should not be simply written off as purely a detector curiosity. this fact motivates a detailed analysis of the ionization-data ("s2") data, taking into account the expected annual modulation spectrum of the signal rate, as well as the dm-induced electron-recoil spectra, which are another powerful discriminant between signal and background. | new constraints and prospects for sub-gev dark matter scattering off electrons in xenon |
very recently, several pulsar timing array collaborations, including cpta, epta, and nanograv, reported their results from searches for an isotropic stochastic gravitational wave background (sgwb), with each finding positive evidence for sgwb. in this work, we assessed the credibility of interpreting the hellings-downs correlated free-spectrum process of epta, ppta, and nanograv as either the result of supermassive black hole binary mergers or various stochastic sgwb sources that originated in the early universe, including first-order phase transitions, cosmic strings, domain walls, and large-amplitude curvature perturbations. our observations show that the current new datasets do not display a strong preference for any specific sgwb source based on bayesian analysis. | gravitational wave sources for pulsar timing arrays |
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