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interest in the idea that primordial black holes (pbhs) might comprise some or all of the dark matter has recently been rekindled following ligo's first direct detection of a binary-black-hole merger. here we revisit the effect of accreting pbhs on the cosmic microwave background (cmb) frequency spectrum and the angular temperature and polarization power spectra. we compute the accretion rate and luminosity of pbhs, accounting for their suppression by compton drag and compton cooling by cmb photons. we estimate the gas temperature near the schwarzschild radius and, hence, the free-free luminosity, accounting for the cooling resulting from collisional ionization when the background gas is mostly neutral. we account approximately for the velocities of pbhs with respect to the background gas. we provide a simple analytic estimate of the efficiency of energy deposition in the plasma. we find that the spectral distortions generated by accreting pbhs are too small to be detected by firas, as well as by future experiments now being considered. we analyze planck cmb temperature and polarization data and find, under our most conservative hypotheses, and at the order-of-magnitude level, that they rule out pbhs with masses ≳1 02 m⊙ as the dominant component of dark matter. | cosmic microwave background limits on accreting primordial black holes |
cosmological correlation functions contain valuable information about the primordial universe, with possible signatures of new massive particles at very high energies. recent developments, including the cosmological bootstrap, bring new perspectives and powerful tools to study these observables. in this paper, we systematically classify inflationary three-point correlators of scalar perturbations using the bootstrap method. for the first time, we derive a complete set of single-exchange cosmological collider bispectra with new shapes and potentially detectable signals. specifically, we focus on the primordial scalar bispectra generated from the exchange of massive particles with all possible boost-breaking interactions during inflation. we introduce three-point "seed" functions, from which we bootstrap the inflationary bispectra of scalar and spinning exchanges using weight-shifting and spin-raising operators. the computation of the seed function requires solving an ordinary differential equation in comoving momenta, a boundary version of the equation of motion satisfied by a propagator that linearly mixes a massive particle with the external light scalars. the resulting correlators are presented in analytic form, for any kinematics. these shapes are of interest for near-future cosmological surveys, as the primordial non-gaussianity in boost-breaking theories can be large. we also identify new features in these shapes, which are phenomenologically distinct from the de sitter invariant cases. for example, the oscillatory shapes around the squeezed limit have different phases. furthermore, when the massive particle has much lower speed of sound than the inflaton, oscillatory features appear around the equilateral configuration. | boostless cosmological collider bootstrap |
numerical simulations have become one of the key tools used by theorists in all the fields of astrophysics and cosmology. the development of modern tools that target the largest existing computing systems and exploit state-of-the-art numerical methods and algorithms is thus crucial. in this paper, we introduce the fully open-source highly-parallel, versatile, and modular coupled hydrodynamics, gravity, cosmology, and galaxy-formation code swift. the software package exploits hybrid task-based parallelism, asynchronous communications, and domain-decomposition algorithms based on balancing the workload, rather than the data, to efficiently exploit modern high-performance computing cluster architectures. gravity is solved for using a fast-multipole-method, optionally coupled to a particle mesh solver in fourier space to handle periodic volumes. for gas evolution, multiple modern flavours of smoothed particle hydrodynamics are implemented. swift also evolves neutrinos using a state-of-the-art particle-based method. two complementary networks of sub-grid models for galaxy formation as well as extensions to simulate planetary physics are also released as part of the code. an extensive set of output options, including snapshots, light-cones, power spectra, and a coupling to structure finders are also included. we describe the overall code architecture, summarize the consistency and accuracy tests that were performed, and demonstrate the excellent weak-scaling performance of the code using a representative cosmological hydrodynamical problem with $\approx$$300$ billion particles. the code is released to the community alongside extensive documentation for both users and developers, a large selection of example test problems, and a suite of tools to aid in the analysis of large simulations run with swift. | swift: a modern highly-parallel gravity and smoothed particle hydrodynamics solver for astrophysical and cosmological applications |
if dark energy, which drives the accelerated expansion of the universe, consists of a light scalar field, it might be detectable as a “fifth force” between normal-matter objects, in potential conflict with precision tests of gravity. chameleon fields and other theories with screening mechanisms, however, can evade these tests by suppressing the forces in regions of high density, such as the laboratory. using a cesium matter-wave interferometer near a spherical mass in an ultrahigh-vacuum chamber, we reduced the screening mechanism by probing the field with individual atoms rather than with bulk matter. we thereby constrained a wide class of dark energy theories, including a range of chameleon and other theories that reproduce the observed cosmic acceleration. | atom-interferometry constraints on dark energy |
vector bosons heavier than 10-22 ev can be viable dark matter candidates with distinctive experimental signatures. ultralight dark matter generally requires a nonthermal origin to achieve the observed density, while still behaving like a pressureless fluid at late times. we show that such a production mechanism naturally occurs for vectors whose mass originates from a dark higgs. if the dark higgs has a large field value after inflation, the energy in the higgs field can be efficiently transferred to vectors through parametric resonance. computing the resulting abundance and spectra requires careful treatment of the transverse and longitudinal components, whose dynamics are governed by distinct equations of motion. we study these in detail and find that the mass of the vector may be as low as 10-18 ev , while making up the majority of the dark matter abundance. this opens up a wide mass range of vector dark matter as cosmologically viable, and further motivates the experimental searches for such particles. | parametric resonance production of ultralight vector dark matter |
the nearby grb221009a at redshift $z=0.1505$ has been observed up to a maximum energy of 18 tev with the lhaaso air shower array. the expected optical depth for a photon with energy $e_\gamma=18$ tev varies between 9.4 and 27.1 according to existing models of the extra-galactic background light (ebl) in the relevant mid infra-red range. the resulting suppression of the flux in several (but not all) ebl models makes it for these ebl models unlikely that this photon could have been observed at the claimed energy. if the photon event and its energy are confirmed and possibly even more photons above 10 tev have been observed, the photon-pair production process would have to be suppressed by mechanisms predicted in extensions of the standard model of particle physics. we consider the possibilities of photon mixing with a light pseudo-scalar (e.g., axion-like particles; alps) in the magnetic field of the host galaxy and the milky way and lorentz invariance violation (liv). in the case of photon-alp mixing, the boost factor would reach values $\sim10^6$ for photon couplings not ruled out by the cast experiment, but limited by other astrophysical constraints. viable scenarios would require either very efficient mixing in or near to the grb or that the largest part of the total luminosity is radiated at tev energies, different from previous grb afterglows. in the case of liv, required boost factors are achievable for a liv breaking energy scale $\lesssim 2\times 10^{29}$~ev ($\lesssim 4\times 10^{21}$~ev) for the linear (quadratic) modification of the dispersion relation. a more simple explanation would be a misidentification of a charged cosmic-ray air shower. | interpretation of multi-tev photons from grb221009a |
to date, 204 individual molecular species, comprised of 16 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. these molecules range in size from 2 atoms to 70, and have been detected across the electromagnetic spectrum from centimeter wavelengths to the ultraviolet. this census presents a summary of the first detection of each molecular species, including the observational facility, wavelength range, transitions, and enabling laboratory spectroscopic work, as well as listing tentative and disputed detections. tables of molecules detected in interstellar ices, external galaxies, protoplanetary disks, and exoplanetary atmospheres are provided. a number of visual representations of these aggregate data are presented and briefly discussed in context. | 2018 census of interstellar, circumstellar, extragalactic, protoplanetary disk, and exoplanetary molecules |
we analyze the boss power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the effective field theory of large-scale structure (eftoflss). specifically, we use the one loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. after validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. we find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. after fixing the spectral tilt to planck preferred value and using a big bang nucleosynthesis prior, we measure $\sigma_8=0.794\pm 0.037$, $h = 0.692\pm 0.011$, and $\omega_m = 0.311\pm 0.010$ to about $4.7\%$, $1.6\%$, and $3.2\%$, at $68\%$ cl, respectively. this represents an error bar reduction with respect to the power spectrum-only analysis of about $30\%$, $18\%$, and $13\%$ respectively. remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the eftoflss in simultaneously predicting several observables. we find no tension with planck. | the boss bispectrum analysis at one loop from the effective field theory of large-scale structure |
recently, the north american nanohertz observatory for gravitational waves (nanograv) claimed the detection of a stochastic common-spectrum process of the pulsar timing array (pta) time residuals from their 12.5 year data, which might be the first detection of the stochastic background of gravitational waves (gws). we show that the amplitude and the power index of such waves imply that they could be the secondary gws induced by the peaked curvature perturbation with a dust-like post inflationary era with −0.091 ≲ w ≲ 0.048. such stochastic background of gws naturally predicts substantial existence of planet-mass primordial black holes (pbhs), which can be the lensing objects for the ultrashort-timescale microlensing events observed by the optical gravitational lensing experiment (ogle). | nanograv hints on planet-mass primordial black holes |
the wealth of incoming and future cosmological observations will allow us to map out the structure and evolution of the observable universe to an unprecedented level of precision. among these observations is the weak gravitational lensing of galaxies, e.g., cosmic shear that measures the minute distortions of background galaxy images by intervening cosmic structure. weak lensing and cosmic shear promise to be a powerful probe of astrophysics and cosmology, constraining models of dark energy, measuring the evolution of structure in the universe, and testing theories of gravity on cosmic scales. however, the intrinsic alignment of galaxies-their shape and orientation before being lensed-may pose a great challenge to the use of weak gravitational lensing as an accurate cosmological probe, and has been identified as one of the primary physical systematic biases in cosmic shear studies. correlations between this intrinsic alignment and the lensing signal can persist even for large physical separations, and isolating the effect of intrinsic alignment from weak lensing is not trivial. a great deal of work in the last two decades has been devoted to understanding and characterizing this intrinsic alignment, which is also a direct and complementary probe of structure formation and evolution in its own right. in this review, we report in a systematic way the state of our understanding of the intrinsic alignment of galaxies, with a particular emphasis on its large-scale impact on weak lensing measurements and methods for its isolation or mitigation. we begin with an introduction to the use of cosmic shear as a probe for cosmology and describe the various physical contributions by intrinsic alignment to the shear or convergence 2- and 3-point correlations. we then review developments in the modeling of the intrinsic alignment signal, including a trend toward attempting to incorporate more accurate nonlinear and single halo effects. the impact on cosmological constraints by the intrinsic alignment of galaxies is also outlined based on these models. we then summarize direct measurements of the large-scale intrinsic alignment signal in various surveys and discuss their constraints on models of intrinsic alignment, as well as progress in utilizing numerical simulations of structure formation to further our understanding of intrinsic alignment. finally, we outline the development of a variety of mitigation techniques for reducing the impact of the intrinsic alignment contamination on weak lensing signals both within a galaxy data set and between complementary probes of gravitational lensing. the methodology and projected impact of these techniques are discussed for both 2- and 3-point correlations. we conclude by presenting a summary and outlook on the state of intrinsic alignment study and its impact on ongoing and planned weak lensing surveys. | the intrinsic alignment of galaxies and its impact on weak gravitational lensing in an era of precision cosmology |
we present a new measurement of the hubble constant h0 and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. first, we measure the time delay of he 0435-1223 from 13-yr light curves obtained as part of the cosmograil project. companion papers detail the modelling of the main deflectors and line-of-sight effects, and how these data are combined to determine the time-delay distance of he 0435-1223. crucially, the measurements are carried out blindly with respect to cosmological parameters in order to avoid confirmation bias. we then combine the time-delay distance of he 0435-1223 with previous measurements from systems b1608+656 and rxj1131-1231 to create a time delay strong lensing probe (tdsl). in flat λ cold dark matter (λcdm) with free matter and energy density, we find h0 =71.9^{+2.4}_{-3.0} {km s^{-1} mpc^{-1}} and ω _{λ }=0.62^{+0.24}_{-0.35}. this measurement is completely independent of, and in agreement with, the local distance ladder measurements of h0. we explore more general cosmological models combining tdsl with other probes, illustrating its power to break degeneracies inherent to other methods. the joint constraints from tdsl and planck are h0 = 69.2_{-2.2}^{+1.4} {km s^{-1} mpc^{-1}}, ω _{λ }=0.70_{-0.01}^{+0.01} and ω _k=0.003_{-0.006}^{+0.004} in open λcdm and h0 =79.0_{-4.2}^{+4.4} {km s^{-1} mpc^{-1}}, ω _de=0.77_{-0.03}^{+0.02} and w=-1.38_{-0.16}^{+0.14} in flat wcdm. in combination with planck and baryon acoustic oscillation data, when relaxing the constraints on the numbers of relativistic species we find neff = 3.34_{-0.21}^{+0.21} in neffλcdm and when relaxing the total mass of neutrinos we find σmν ≤ 0.182 ev in mνλcdm. finally, in an open wcdm in combination with planck and cosmic microwave background lensing, we find h0 =77.9_{-4.2}^{+5.0} {km s^{-1} mpc^{-1}}, ω _de=0.77_{-0.03}^{+0.03}, ω _k=-0.003_{-0.004}^{+0.004} and w=-1.37_{-0.23}^{+0.18}. | h0licow - v. new cosmograil time delays of he 0435-1223: h0 to 3.8 per cent precision from strong lensing in a flat λcdm model |
we study the large-scale anisotropy of the universe by measuring the dipole in the angular distribution of a flux-limited, all-sky sample of 1.36 million quasars observed by the wide-field infrared survey explorer (wise). this sample is derived from the new catwise2020 catalog, which contains deep photometric measurements at 3.4 and 4.6 μm from the cryogenic, post-cryogenic, and reactivation phases of the wise mission. while the direction of the dipole in the quasar sky is similar to that of the cosmic microwave background (cmb), its amplitude is over twice as large as expected, rejecting the canonical, exclusively kinematic interpretation of the cmb dipole with a p-value of 5 × 10-7 (4.9σ for a normal distribution, one-sided), the highest significance achieved to date in such studies. our results are in conflict with the cosmological principle, a foundational assumption of the concordance λcdm model. | a test of the cosmological principle with quasars |
we present measurements of the baryon acoustic oscillation (bao) scale in redshift-space using the clustering of quasars. we consider a sample of 147 000 quasars from the extended baryon oscillation spectroscopic survey (eboss) distributed over 2044 square degrees with redshifts 0.8 < z < 2.2 and measure their spherically averaged clustering in both configuration and fourier space. our observational data set and the 1400 simulated realizations of the data set allow us to detect a preference for bao that is greater than 2.8σ. we determine the spherically averaged bao distance to z = 1.52 to 3.8 per cent precision: dv(z = 1.52) = 3843 ± 147(rd/rd, fid)mpc. this is the first time the location of the bao feature has been measured between redshifts 1 and 2. our result is fully consistent with the prediction obtained by extrapolating the planck flat λcdm best-fitting cosmology. all of our results are consistent with basic large-scale structure (lss) theory, confirming quasars to be a reliable tracer of lss, and provide a starting point for numerous cosmological tests to be performed with eboss quasar samples. we combine our result with previous, independent, bao distance measurements to construct an updated bao distance-ladder. using these bao data alone and marginalizing over the length of the standard ruler, we find ωλ > 0 at 6.6σ significance when testing a λcdm model with free curvature. | the clustering of the sdss-iv extended baryon oscillation spectroscopic survey dr14 quasar sample: first measurement of baryon acoustic oscillations between redshift 0.8 and 2.2 |
hard x-ray (≥10 kev) observations of active galactic nuclei (agns) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. the 70-month swift/bat all-sky survey, which probes the 14-195 kev energy range, has currently detected 838 agns. we report here on the broadband x-ray (0.3-150 kev) characteristics of these agns, obtained by combining xmm-newton, swift/xrt, asca, chandra, and suzaku observations in the soft x-ray band (≤slant 10 kev) with 70-month averaged swift/bat data. the nonblazar agns of our sample are almost equally divided into unobscured ({n}{{h}}< {10}22 {{cm}}-2) and obscured ({n}{{h}}≥slant {10}22 {{cm}}-2) agns, and their swift/bat continuum is systematically steeper than the 0.3-10 kev emission, which suggests that the presence of a high-energy cutoff is almost ubiquitous. we discuss the main x-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured agns. | bat agn spectroscopic survey. v. x-ray properties of the swift/bat 70-month agn catalog |
this report summarizes the findings of the cf1 topical subgroup to snowmass 2021, which was focused on particle dark matter. one of the most important scientific goals of the next decade is to reveal the nature of dark matter (dm). to accomplish this goal, we must delve deep, to cover high priority targets including weakly-interacting massive particles (wimps), and search wide, to explore as much motivated dm parameter space as possible. a diverse, continuous portfolio of experiments at large, medium, and small scales that includes both direct and indirect detection techniques maximizes the probability of discovering particle dm. detailed calibrations and modeling of signal and background processes are required to make a convincing discovery. in the event that a candidate particle is found through different means, for example at a particle collider, the program described in this report is also essential to show that it is consistent with the actual cosmological dm. the us has a leading role in both direct and indirect detection dark matter experiments -- to maintain this leading role, it is imperative to continue funding major experiments and support a robust r\&d program. | report of the topical group on particle dark matter for snowmass 2021 |
an axion-like field comprising ∼10 % of the energy density of the universe near matter-radiation equality is a candidate to resolve the hubble tension; this is the "early dark energy" (ede) model. however, as shown in hill et al., the model fails to simultaneously resolve the hubble tension and maintain a good fit to both cosmic microwave background (cmb) and large-scale structure (lss) data. here, we use redshift-space galaxy clustering data to sharpen constraints on the ede model. we perform the first ede analysis using the full-shape power spectrum likelihood from the baryon oscillation spectroscopic survey (boss), based on the effective field theory (eft) of lss. the inclusion of this likelihood in the ede analysis yields a 25% tighter error bar on h0 compared to primary cmb data alone, yielding h0=68.5 4-0.95+0.52 km /s /mpc (68% c.l.). in addition, we constrain the maximum fractional energy density contribution of the ede to fede<0.072 (95% c.l.). we explicitly demonstrate that the eft boss likelihood yields much stronger constraints on ede than the standard boss likelihood. including further information from photometric lss surveys,the constraints narrow by an additional 20%, yielding h0=68.7 3-0.69+0.42 km /s /mpc (68% c.l.) and fede<0.053 (95% c.l.). these bounds are obtained without including local-universe h0 data, which is in strong tension with the cmb and lss, even in the ede model. we also refute claims that markov-chain monte carlo analyses of ede that omit sh0es from the combined dataset yield misleading posteriors. finally, we show that upcoming euclid/desi-like spectroscopic galaxy surveys will greatly improve the ede constraints. we conclude that current data preclude the ede model as a resolution of the hubble tension, and that future lss surveys can close the remaining parameter space of this model. | constraining early dark energy with large-scale structure |
the well-known tensions on the cosmological parameters h_0 and σ _8 within the λ cdm cosmology shown by the planck-cmb and lss data are possibly due to the systematics in the data or our ignorance of some new physics beyond the λ cdm model. in this letter, we focus on the second possibility, and investigate a minimal extension of the λ cdm model by allowing a coupling between its dark sector components (dark energy and dark matter). we analyze this scenario with planck-cmb, kids and hst data, and find that the h_0 and σ _8 tensions disappear. in the joint analyses with planck, hst and kids data, we find non-zero coupling in the dark sector up to 99% cl. thus, we find a strong statistical support from the observational data for an interaction in the dark sector of the universe while solving the h_0 and σ _8 tensions simultaneously. | dark sector interaction: a remedy of the tensions between cmb and lss data |
announcing the release v7.2 of the milliquas (million quasars) catalogue which presents all published quasars to 30 april 2021, including vlass radio associations for the first time, and concluding the audit of quasars from sdss-dr16q and earlier sdss releases. the totals are 829666 classified type-i qsos/agn, 703348 quasar candidates of 60%-100% pqso, plus type-ii objects and blazars which bring the total count to 1573824. radio and/or x-ray associations, including probable double radio lobes, are shown for 333638 entries. gaia-dr2 astrometry is given for most objects, as available. the catalogue is available on multiple sites. the inclusion of the sdss-dr16q quasars was a complex task with emergent issues which resulted in 13443 dr16q entries being dropped, 1.79% of their total. there are also 1701 quasars included from earlier visual sdss releases, as well as 14232 quasars from the sdss-dr16 pipeline catalogue. all these are explained here, including the validation of 677 additional high-redshift (z>=3.5) sdss quasars which were not included in dr16q. | the million quasars (milliquas) v7.2 catalogue, now with vlass associations. the inclusion of sdss-dr16q quasars is detailed |
we present a brief overview of attempts to construct de sitter vacua in string theory and explain how the results of this 20-year endeavor could point to the fact that string theory harbors no de sitter vacua at all. making such a statement is often considered controversial and “bad news for string theory”. we discuss how perhaps the opposite can be true. | what if string theory has no de sitter vacua? |
we undertake a careful analysis of stochastic gravitational wave production from cosmological phase transitions in an expanding universe, studying both a standard radiation as well as a matter dominated history. we analyze in detail the dynamics of the phase transition, including the false vacuum fraction, bubble lifetime distribution, bubble number density, mean bubble separation, etc., for an expanding universe. we also study the full set of differential equations governing the evolution of plasma and the scalar field during the phase transition and generalize results obtained in minkowski spacetime. in particular, we generalize the sound shell model to the expanding universe and determine the velocity field power spectrum. this ultimately provides an accurate calculation of the gravitational wave spectrum seen today for the dominant source of sound waves. for the amplitude of the gravitational wave spectrum visible today, we find a suppression factor arising from the finite lifetime of the sound waves and compare with the commonly used result in the literature, which corresponds to the asymptotic value of our suppression factor. we point out that the asymptotic value is only applicable for a very long lifetime of the sound waves, which is highly unlikely due to the onset of shocks, turbulence and other damping processes. we also point out that features of the gravitational wave spectral form may hold the tantalizing possibility of distinguishing between different expansion histories using phase transitions. | phase transitions in an expanding universe: stochastic gravitational waves in standard and non-standard histories |
we introduce the uchuu suite of large high-resolution cosmological n-body simulations. the largest simulation, named uchuu, consists of 2.1 trillion (12 8003) dark matter particles in a box of side-length 2.0 $\, h^{-1} \, \rm gpc$, with particle mass of 3.27 × 108$\, h^{-1}\, \rm m_{\odot }$. the highest resolution simulation, shin-uchuu, consists of 262 billion (64003) particles in a box of side-length 140 $\, h^{-1} \, \rm mpc$, with particle mass of 8.97 × 105$\, h^{-1}\, \rm m_{\odot }$. combining these simulations, we can follow the evolution of dark matter haloes and subhaloes spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume. in this first paper, we present basic statistics, dark matter power spectra, and the halo and subhalo mass functions, which demonstrate the wide dynamic range and superb statistics of the uchuu suite. from an analysis of the evolution of the power spectra, we conclude that our simulations remain accurate from the baryon acoustic oscillation scale down to the very small. we also provide parameters of a mass-concentration model, which describes the evolution of halo concentration and reproduces our simulation data to within 5 per cent for haloes with masses spanning nearly eight orders of magnitude at redshift 0 ≤ z ≤ 14. there is an upturn in the mass-concentration relation for the population of all haloes and of relaxed haloes at z ≳ 0.5, whereas no upturn is detected at z < 0.5. we make publicly available various n-body products as part of uchuu data release 1 on the skies & universes site.1 future releases will include gravitational lensing maps and mock galaxy, x-ray cluster, and active galactic nucleus catalogues. | the uchuu simulations: data release 1 and dark matter halo concentrations |
one of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a z_2 symmetry. using the gambit package and combining results from four independent samplers, we present bayesian and frequentist global fits of this model. we vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. we include the dark matter relic density measured by planck, direct searches with lux, pandax, supercdms and xenon100, limits on invisible higgs decays from the large hadron collider, searches for high-energy neutrinos from dark matter annihilation in the sun with icecube, and searches for gamma rays from annihilation in dwarf galaxies with the fermi-lat. viable solutions remain at couplings of order unity, for singlet masses between the higgs mass and about 300 gev, and at masses above ∼ 1 tev. only in the latter case can the scalar singlet constitute all of dark matter. frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the higgs, can also account for all of dark matter, and remains viable. however, bayesian considerations show this region to be rather fine-tuned. | status of the scalar singlet dark matter model |
we critically examine the state of current constraints on the dark energy (de) equation of state (eos) $w$. our study is partially motivated by the observation that, while broadly consistent with the cosmological constant value $w=-1$, several independent probes appear to point towards a slightly phantom eos ($w \sim -1.03$). we pay attention to the apparent preference for phantom de from planck cosmic microwave background (cmb) data alone, whose origin we study in detail and attribute to a wide range of (physical and geometrical) effects. we deem the combination of planck cmb, baryon acoustic oscillations, type ia supernovae, and cosmic chronometers data to be particularly trustworthy, inferring from this final consensus dataset $w=-1.013^{+0.038}_{-0.043}$, in excellent agreement with the cosmological constant value. overall, despite a few scattered hints, we find no compelling evidence forcing us away from the cosmological constant (yet). | the state of the dark energy equation of state circa 2023 |
we study a new source of stochastic gravitational wave background (sgwb) from the final collapse of a string-wall network. in the context of $n_{\rm dw}=1$ axionic string-wall network, the final collapse of walls bounded by strings can release gravitational waves (gws). this source is typically considered negligible due to its subdominance compared to gw emissions throughout the long-term evolution in the scaling regime. however, in some cases, a network can be driven outside of horizon by inflation and later re-enter horizon. then, the network's final collapse after re-entering horzion becomes the dominant gw source and therefore cannot be neglected. our caculation of the corresponding gw spectrum suggests it could potentially explain the nano-hertz sgwb signal possibly detected by various pulsar timing array experiments. in addition, with different parameter choices, the resultant gws could be probed by various gw interferometry experiments. | stochastic gravitational wave background: birth from axionic string-wall death |
kination denotes an era in the cosmological history corresponding to an equation of state $\omega=+1$ such that the total energy density of the universe redshifts as the sixth inverse power of the scale factor. this arises if the universe is dominated by the kinetic energy of a scalar field. it has often been motivated in the literature as an era following inflation, taking place before the radiation era. in this paper, we review instead the possibility that kination is disconnected from primordial inflation and occurs much later, inside the standard model radiation era. we study the implications on all main sources of primordial gravitational waves. we show how this leads to very distinctive peaked spectra in the stochastic background of long-lasting cosmological sources of gravitational waves, namely the irreducible gravitational waves from inflation, and gravitational waves from cosmic strings, both local and global, with promising observational prospects. we present model-independent signatures and detectability predictions at ska, ligo, lisa, et, ce, bbo, as a function of the energy scale and duration of the kination era. we then argue that such intermediate kination era is in fact symptomatic in a large class of axion models. we analyse in details the scalar field dynamics, the working conditions and constraints in the underlying models. we present the gravitational-wave predictions as a function of particle physics parameters. we derive the general relation between the gravitational-wave signal and the axion dark matter abundance as well as the baryon asymmetry. we investigate the predictions for the special case of the qcd axion. the key message is that gravitational-waves of primordial origin represent an alternative experimental probe of axion models. | kination cosmology from scalar fields and gravitational-wave signatures |
active galactic nuclei (agn) are powered by the accretion of material onto a supermassive black hole (smbh) and are among the most luminous objects in the universe. however, the huge radiative power of most agn cannot be seen directly, as the accretion is hidden behind gas and dust that absorb many of the characteristic observational signatures. this obscuration presents an important challenge for uncovering the complete agn population and understanding the cosmic evolution of smbhs. in this review, we describe a broad range of multiwavelength techniques that are currently being employed to identify obscured agn, and we assess the reliability and completeness of each technique. we follow with a discussion of the demographics of obscured agn activity, explore the nature and physical scales of the obscuring material, and assess the implications of obscured agn for observational cosmology. we conclude with an outline of the prospects for future progress from both observations and theoretical models, and we highlight some of the key outstanding questions. | obscured active galactic nuclei |
dark matter could be a composite state of a confining sector with an approximate scale symmetry. we consider the case where the associated pseudo-goldstone boson, the dilaton, mediates its interactions with the standard model. when the confining phase transition in the early universe is supercooled, its dynamics allows for dark matter masses up to 106 tev. we derive the precise parameter space compatible with all experimental constraints, finding that this scenario can be tested partly by telescopes and entirely by gravitational waves. | supercool composite dark matter beyond 100 tev |
it is commonly assumed that the energy density of the universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. while the abundance of light elements indicates that the universe was radiation dominated during big bang nucleosynthesis (bbn), there is scant evidence that the universe was radiation dominated prior to bbn. it is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. in this paper, we review various possible causes and consequences of deviations from radiation domination in the early universe - taking place either before or after bbn - and the constraints on them, as they have been discussed in the literature during the recent years. | the first three seconds: a review of possible expansion histories of the early universe |
rotations of an axion field in field space provide a natural origin for an era of kination domination, where the energy density is dominated by the kinetic term of the axion field, preceded by an early era of matter domination. remarkably, no entropy is produced at the end of matter domination and hence these eras of matter and kination domination may occur even after big bang nucleosynthesis. we derive constraints on these eras from both the cosmic microwave background and big bang nucleosynthesis. we investigate how this cosmological scenario affects the spectrum of possible primordial gravitational waves and find that the spectrum features a triangular peak. we discuss how future observations of gravitational waves can probe the viable parameter space, including regions that produce axion dark matter by the kinetic misalignment mechanism or the baryon asymmetry by axiogenesis. for qcd axion dark matter produced by the kinetic misalignment mechanism, a modification to the inflationary gravitational wave spectrum occurs above 0.01 hz and, for high values of the energy scale of inflation, the prospects for discovery are good. we briefly comment on implications for structure formation of the universe. | gravitational wave and cmb probes of axion kination |
we measure the anisotropic clustering of the quasar sample from data release 16 (dr16) of the sloan digital sky survey iv extended baryon oscillation spectroscopic survey (eboss). a sample of 343 708 spectroscopically confirmed quasars between redshift 0.8 < z < 2.2 are used as tracers of the underlying dark matter field. in comparison with dr14 sample, the final sample doubles the number of objects as well as the survey area. in this paper, we present the analysis in configuration space by measuring the two-point correlation function and decomposing it using the legendre polynomials. for the full-shape analysis of the legendre multipole moments, we measure the baryon acoustic oscillation (bao) distance and the growth rate of the cosmic structure. at an effective redshift of zeff = 1.48, we measure the comoving angular diameter distance dm(zeff)/rdrag = 30.66 ± 0.88, the hubble distance dh(zeff)/rdrag = 13.11 ± 0.52, and the product of the linear growth rate and the rms linear mass fluctuation on scales of $8 \, h^{-1}\, {\rm mpc}$ , fσ8(zeff) = 0.439 ± 0.048. the accuracy of these measurements is confirmed using an extensive set of mock simulations developed for the quasar sample. the uncertainties on the distance and growth rate measurements have been reduced substantially (∼45 and ∼30 per cent) with respect to the dr14 results. we also perform a bao-only analysis to cross check the robustness of the methodology of the full-shape analysis. combining our analysis with the fourier-space analysis, we arrive at $d^{{\bf c}}_{\rm m}(z_{\rm eff})/r_{\rm drag} = 30.21 \pm 0.79$ , $d^{{\bf c}}_{\rm h}(z_{\rm eff})/r_{\rm drag} = 13.23 \pm 0.47$ , and $f\sigma _8^{{\bf c}}(z_{\rm eff}) = 0.462 \pm 0.045$ . | the completed sdss-iv extended baryon oscillation spectroscopic survey: bao and rsd measurements from anisotropic clustering analysis of the quasar sample in configuration space between redshift 0.8 and 2.2 |
we have used the publicly released dark energy survey (des) data to hunt for new satellites of the milky way (mw) in the southern hemisphere. our search yielded a large number of promising candidates. in this paper, we announce the discovery of nine new unambiguous ultra-faint objects, whose authenticity can be established with the des data alone. based on the morphological properties, three of the new satellites are dwarf galaxies, one of which is located at the very outskirts of the mw, at a distance of 380 kpc. the remaining six objects have sizes and luminosities comparable to the segue 1 satellite and cannot be classified straightforwardly without follow-up spectroscopic observations. the satellites we have discovered cluster around the lmc and the smc. we show that such spatial distribution is unlikely under the assumption of isotropy, and, therefore, conclude that at least some of the new satellites must have been associated with the magellanic clouds in the past. | beasts of the southern wild: discovery of nine ultra faint satellites in the vicinity of the magellanic clouds. |
what is the maximum possible strength of a first-order electroweak phase transition and the resulting gravitational wave (gw) signal? while naively one might expect that supercooling could increase the strength of the transition to very high values, for strong supercooling the universe is no longer radiation-dominated and the vacuum energy of the unstable minimum of the potential dominates the expansion, which can jeopardize the successful completion of the phase transition. after providing a general treatment for the nucleation, growth and percolation of broken phase bubbles during a first-order phase transition that encompasses the case of significant supercooling, we study the conditions for successful bubble percolation and completion of the electroweak phase transition in theories beyond the standard model featuring polynominal potentials. for such theories, these conditions set a lower bound on the temperature of the transition. since the plasma cannot be significantly diluted, the resulting gw signal originates mostly from sound waves and turbulence in the plasma, rather than bubble collisions. we find the peak frequency of the gw signal from the phase transition to be generically f gtrsim 10-4 hz. we also study the condition for gw production by sound waves to be long-lasting (gw source active for approximately a hubble time), showing it is generally not fulfilled in concrete scenarios. because of this the sound wave gw signal could be weakened, with turbulence setting in earlier, resulting in a smaller overall gw signal as compared to current literature predictions. | on the maximal strength of a first-order electroweak phase transition and its gravitational wave signal |
a new generation of neutrino experiments is testing the 4.7 σ anomalous excess of electronlike events observed in miniboone. this is of huge importance for particle physics, astrophysics, and cosmology, not only because of the potential discovery of physics beyond the standard model, but also because the lessons we will learn about neutrino-nucleus interactions will be crucial for the worldwide neutrino program. microboone has recently released results that appear to disfavor several explanations of the miniboone anomaly. here, we show quantitatively that microboone results, while a promising start, unquestionably do not probe the full parameter space of sterile neutrino models hinted at by miniboone and other data, nor do they probe the νe interpretation of the miniboone excess in a model-independent way. | microboone and the νe interpretation of the miniboone low-energy excess |
we present a new bound on the ultralight axion (ula) dark matter mass ma, using the lyman-alpha forest to look for suppressed cosmic structure growth: a 95% lower limit ma>2 ×10-20 ev . this strongly disfavors (>99.7 % credibility) the canonical ula with 10-22 ev <ma<10-21 ev , motivated by the string axiverse and solutions to possible tensions in the cold dark matter model. we strengthen previous equivalent bounds by about an order of magnitude. we demonstrate the robustness of our results using an optimized emulator of improved hydrodynamical simulations. | strong bound on canonical ultralight axion dark matter from the lyman-alpha forest |
identifying the nature of dark matter (dm) has long been a pressing question for particle physics. in the face of ever-more-powerful exclusions and null results from large-exposure searches for tev-scale dm interacting with nuclei, a significant amount of attention has shifted to lighter (sub-gev) dm candidates. direct detection of the light dm in our galaxy by observing dm scattering off a target system requires new approaches compared to prior searches. lighter dm particles have less available kinetic energy, and achieving a kinematic match between dm and the target mandates the proper treatment of collective excitations in condensed matter systems, such as charged quasiparticles or phonons. in this context, the condensed matter physics of the target material is crucial, necessitating an interdisciplinary approach. in this review, we provide a self-contained introduction to direct detection of kev-gev dm with condensed matter systems. we give a brief survey of dm models and basics of condensed matter, while the bulk of the review deals with the theoretical treatment of dm-nucleon and dm-electron interactions. we also review recent experimental developments in detector technology, and conclude with an outlook for the field of sub-gev dm detection over the next decade. | searches for light dark matter using condensed matter systems |
we revisit the cosmological and astrophysical constraints on the fraction of the dark matter in primordial black holes (pbhs) with an extended mass function. we consider a variety of mass functions, all of which are described by three parameters: a characteristic mass and width and a dark matter fraction. various observations then impose constraints on the dark matter fraction as a function of the first two parameters. we show how these constraints relate to those for a monochromatic mass function, demonstrating that they usually become more stringent in the extended case than the monochromatic one. considering only the well-established bounds, and neglecting the ones that depend on additional astrophysical assumptions, we find that there are three mass windows, around 5 ×10-16m⊙ , 2 ×10-14m⊙ and 25 - 100 m⊙ , where pbhs can constitute all the dark matter. however, if one includes all the bounds, pbhs can only constitute of order 10% of the dark matter. | primordial black hole constraints for extended mass functions |
new physics increasing the expansion rate just prior to recombination is among the least unlikely solutions to the hubble tension and would be expected to leave an important signature in the early integrated sachs-wolfe (eisw) effect, a source of cosmic microwave background (cmb) anisotropies arising from the time variation of gravitational potentials when the universe was not completely matter dominated. why, then, is there no clear evidence for new physics from the cmb alone, and why does the λ cold dark matter (λ cdm ) model fit cmb data so well? these questions and the vastness of the hubble tension theory model space provide the motivation for general consistency tests of λ cdm . i perform an eisw-based consistency test of λ cdm introducing the parameter aeisw, which rescales the eisw contribution to the cmb power spectra. a fit to planck cmb data yields aeisw=0.988 ±0.027 , in perfect agreement with the λ cdm expectation aeisw=1 and posing an important challenge for early-time new physics, which i illustrate in a case study focused on early dark energy (ede). i explicitly show that the increase in ωc needed for ede to preserve the fit to the cmb, which has been argued to worsen the fit to weak lensing and galaxy clustering measurements, is specifically required to lower the amplitude of the eisw effect, which would otherwise exceed λ cdm 's prediction by ≈20 %: this is a generic problem beyond ede that likely applies to most models enhancing the expansion rate around recombination. early-time new physics models invoked to address the hubble tension are therefore faced with the significant challenge of making a similar prediction to λ cdm for the eisw effect while not degrading the fit to other measurements in doing so. | consistency tests of λ cdm from the early integrated sachs-wolfe effect: implications for early-time new physics and the hubble tension |
we discuss the most general field equations for cosmological spacetimes for theories of gravity based on non-linear extensions of the non-metricity scalar and the torsion scalar. our approach is based on a systematic symmetry-reduction of the metric-affine geometry which underlies these theories. while for the simplest conceivable case the connection disappears from the field equations and one obtains the friedmann equations of general relativity, we show that in ${{{\gamma}}^{\alpha }}_{\mu \nu }=0$ cosmology the connection generically modifies the metric field equations and that some of the connection components become dynamical. we show that $f(\mathbb{q})$ cosmology contains the exact general relativity solutions and also exact solutions which go beyond. in $f(\mathbb{q})$ cosmology, however, the connection is completely fixed and not dynamical. | revisiting cosmologies in teleparallelism |
on 2022 july 13, nasa released to the whole world the data obtained by the james webb space telescope (jwst) early release observations (ero). these are the first set of science-grade data from this long-awaited facility, marking the beginning of a new era in astronomy. in the study of the early universe, jwst will allow us to push far beyond z ≈ 11, the redshift boundary previously imposed by the 1.7 μm red cutoff of the hubble space telescope (hst). in contrast, jwst's nircam reaches ~5 μm. among the jwst ero targets there is a nearby galaxy cluster smacs 0723-73, which is a massive cluster and has been long recognized as a potential "cosmic telescope" in amplifying background galaxies. the ero six-band nircam observations on this target have covered an additional flanking field not boosted by gravitational lensing, which also sees far beyond hst. here we report the result from our search of candidate objects at z > 11 using these ero data. in total, there are 87 such objects identified by using the standard "dropout" technique. these objects are all detected in multiple bands and therefore cannot be spurious. for most of them, their multiband colors are inconsistent with known types of contaminants. if the detected dropout signature is interpreted as the expected lyman break, it implies that these objects are at z ≈ 11-20. the large number of such candidate objects at such high redshifts is not expected from the previously favored predictions and demands further investigations. jwst spectroscopy on such objects will be critical. | first batch of z ≈ 11-20 candidate objects revealed by the james webb space telescope early release observations on smacs 0723-73 |
we present the data release 12 quasar catalog (dr12q) from the baryon oscillation spectroscopic survey (boss) of the sloan digital sky survey iii. this catalog includes all sdss-iii/boss objects that were spectroscopically targeted as quasar candidates during the full survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities mi [z = 2] < -20.5 (in a λcdm cosmology with h0 = 70 km s-1 mpc-1, ωm = 0.3, and ωλ = 0.7), and either display at least one emission line with a full width at half maximum (fwhm) larger than 500 km s-1 or, if not, have interesting/complex absorption features. the catalog also includes previously known quasars (mostly from sdss-i and ii) that were reobserved by boss. the catalog contains 297 301 quasars (272 026 are new discoveries since the beginning of sdss-iii) detected over 9376 deg2 with robust identification and redshift measured by a combination of principal component eigenspectra. the number of quasars with z > 2.15 (184 101, of which 167 742 are new discoveries) is about an order of magnitude greater than the number of z > 2.15 quasars known prior to boss. redshifts and fwhms are provided for the strongest emission lines (c iv, c iii], mg ii). the catalog identifies 29 580 broad absorption line quasars and lists their characteristics. for each object, the catalog presents five-band (u, g, r, i, z) ccd-based photometry with typical accuracy of 0.03 mag together with some information on the optical morphology and the selection criteria. when available, the catalog also provides information on the optical variability of quasars using sdss and palomar transient factory multi-epoch photometry. the catalog also contains x-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. the calibrated digital spectra, covering the wavelength region 3600-10 500 å at a spectral resolution in the range 1300 < r < 2500, can be retrieved from the sdss catalog archive server. we also provide a supplemental list of an additional 4841 quasars that have been identified serendipitously outside of the superset defined to derive the main quasar catalog. | the sloan digital sky survey quasar catalog: twelfth data release |
the neutrino floor is a theoretical lower limit on wimp-like dark matter models that are discoverable in direct detection experiments. it is commonly interpreted as the point at which dark matter signals become hidden underneath a remarkably similar-looking background from neutrinos. however, it has been known for some time that the neutrino floor is not a hard limit, but can be pushed past with sufficient statistics. as a consequence, some have recently advocated for calling it the "neutrino fog" instead. the downside of current methods of deriving the neutrino floor are that they rely on arbitrary choices of experimental exposure and energy threshold. here we propose to define the neutrino floor as the boundary of the neutrino fog, and develop a calculation free from these assumptions. the technique is based on the derivative of a hypothetical experimental discovery limit as a function of exposure, and leads to a neutrino floor that is only influenced by the systematic uncertainties on the neutrino flux normalizations. our floor is broadly similar to those found in the literature, but differs by almost an order of magnitude in the sub-gev range, and above 20 gev. | new definition of the neutrino floor for direct dark matter searches |
the dark energy spectroscopic instrument (desi) is currently measuring the spectra of 40\,million galaxies and quasars, the largest such survey ever made to probe the nature of cosmological dark energy. the 4-meter mayall telescope at kitt peak national observatory has been adapted for desi, including the construction of a 3.2-degree diameter prime focus corrector that focuses astronomical light onto a 0.8-meter diameter focal surface with excellent image quality over the desi bandpass of 360-980nm. the wide-field corrector includes six lenses, as large as 1.1-meters in diameter and as heavy as 237\,kilograms, including two counter-rotating wedged lenses that correct for atmospheric dispersion over zenith angles from 0 to 60 degrees. the lenses, cells, and barrel assembly all meet precise alignment tolerances on the order of tens of microns. the barrel alignment is maintained throughout a range of observing angles and temperature excursions in the mayall dome by use of a hexapod, which is itself supported by a new cage, ring, and truss structure. in this paper we describe the design, fabrication, and performance of the new corrector and associated structure, focusing on how they meet desi requirements. in particular we describe the prescription and specifications of the lenses, design choices and error budgeting of the barrel assembly, stray light mitigations, and integration and test at the mayall telescope. we conclude with some validation highlights that demonstrate the successful corrector on-sky performance, and list some lessons learned during the multi-year fabrication phase. | the optical corrector for the dark energy spectroscopic instrument |
there is a growing sense of `crisis' in the dark-matter particle community, which arises from the absence of evidence for the most popular candidates for dark-matter particles—such as weakly interacting massive particles, axions and sterile neutrinos—despite the enormous effort that has gone into searching for these particles. here we discuss what we have learned about the nature of dark matter from past experiments and the implications for planned dark-matter searches in the next decade. we argue that diversifying the experimental effort and incorporating astronomical surveys and gravitational-wave observations is our best hope of making progress on the dark-matter problem. | a new era in the search for dark matter |
the supersymmetric model is one of the most attractive extensions of the standard model of particle physics. in light of the most recently reported anomaly of the muon g -2 measurement by the fermilab e989 experiment, and the excesses of gamma rays at the galactic center observed by fermi-lat space telescope, as well as the antiproton excess observed by the alpha magnetic spectrometer, we propose to account for all these anomalies or excesses in the next-to-minimal supersymmetric standard model (nmssm). considering various experimental constraints including the higgs mass, b -physics, collider data, dark matter relic density and direct detections, we find that a ~ 60 gev bino-like neutralino is able to successfully explain all these observations. our scenario can be sensitively probed by future direct detection experiments. | a common origin of muon g-2 anomaly, galaxy center gev excess and ams-02 anti-proton excess in the nmssm |
primordial black holes (pbhs) have long been a candidate for the elusive dark matter (dm), and remain poorly constrained in the ∼20 - 100 m⊙ mass range. pbh binaries were recently suggested as the possible source of ligo's first detections. in this paper, we thoroughly revisit existing estimates of the merger rate of pbh binaries. we compute the probability distribution of orbital parameters for pbh binaries formed in the early universe, accounting for tidal torquing by all other pbhs, as well as standard large-scale adiabatic perturbations. we then check whether the orbital parameters of pbh binaries formed in the early universe can be significantly affected between formation and merger. our analytic estimates indicate that the tidal field of halos and interactions with other pbhs, as well as dynamical friction by unbound standard dm particles, do not do significant work on nor torque pbh binaries. we estimate the torque due to baryon accretion to be much weaker than previous calculations, albeit possibly large enough to significantly affect the eccentricity of typical pbh binaries. we also revisit the pbh-binary merger rate resulting from gravitational capture in present-day halos, accounting for poisson fluctuations. if binaries formed in the early universe survive to the present time, as suggested by our analytic estimates, they dominate the total pbh merger rate. moreover, this merger rate would be orders of magnitude larger than ligo's current upper limits if pbhs make a significant fraction of the dark matter. as a consequence, ligo would constrain ∼10 - 300 m⊙ pbhs to constitute no more than ∼1 % of the dark matter. to make this conclusion fully robust, though, numerical study of several complex astrophysical processes—such as the formation of the first pbh halos and how they may affect pbh binaries, as well as the accretion of gas onto an extremely eccentric binary—is needed. | merger rate of primordial black-hole binaries |
the recently detected stochastic signal by several pulsar timing array collaborations, offers an opportunity to scrutinize the fundamental properties of gravity, including the potential mass of the graviton. in this study, we analyze the nanograv 15-year data set to search for a stochastic gravitational wave background with modified hellings-downs correlations predicted by massive gravity. while the bayesian analysis comparing the massive gravity to massless gravity within the effective searchable mass range of $m_g\in [3\times 10^{-25}, 8 \times 10^{-24}]\,\rm{ev}/c^2$ does not yield an explicit upper bound as all the bayes factors are smaller than $3$, the combined consideration of the minimum frequency inherent in a massive gravity and the observed spectrum leads to an upper limit of $m_g<8.2\times 10^{-24}\,\rm{ev}/c^2$. | constraining the graviton mass with the nanograv 15-year data set |
recently, several major pulsar timing array (pta) collaborations have assembled strong evidence for the existence of a gravitational-wave background at frequencies around the nanohertz regime. assuming that the pta signal is attributed to scalar-induced gravitational waves, we jointly employ the pta data from the nanograv 15-year data set, ppta dr3, and epta dr2 to probe the conditions of the early universe. specifically, we explore the equation of state parameter ($w$), the sound speed ($c_s$), and the reheating temperature ($t_\mathrm{rh}$), finding $w=0.60^{+0.32}_{-0.39}$, $c_s\gtrsim 0.09$, and $t_\mathrm{rh}\lesssim 0.2\,\mathrm{gev}$ for a lognormal power spectrum of the curvature perturbation. furthermore, we compute bayes factors to compare different models against the radiation domination model ($c_s^2 = w = 1/3$), effectively excluding the pressure-less fluid domination model. our study underscores the significance of scalar-induced gravitational waves as a powerful tool to explore the nature of the early universe. | simultaneously probing the sound speed and equation of state of the early universe with pulsar timing arrays |
the existence of ultralight axion (ula) with mass o (10-26ev) is not favored by the cmb observations in the standard λcdm model. we show that the inclusion of early dark energy (ede) will lift the cmb-lockdown on such ula, and possibly other forms of dark matter beyond cold dark matter. by performing monte carlo markov chain analysis, it is found that, as opposed to λcdm, the ads-ede cosmology (with an anti-de sitter phase around recombination) now allows the existence of axion with mass 10-26 ev and predicts 6% of the matter in our universe to be such ula, which can also help alleviating the s8 tension in ede. | alleviating both h0 and s8 tensions: early dark energy lifts the cmb-lockdown on ultralight axion |
we report upper limits on the epoch of reionization 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights of data (~36 hr of integration) from phase i of the hydrogen epoch of reionization array (hera). the phase i data show evidence for systematics that can be largely suppressed with systematic models down to a dynamic range of ~109 with respect to the peak foreground power. this yields a 95% confidence upper limit on the 21 cm power spectrum of ${{\rm{\delta }}}_{21}^{2}\leqslant {(30.76)}^{2}\ {\mathrm{mk}}^{2}$ at k = 0.192 h mpc-1 at z = 7.9, and also ${{\rm{\delta }}}_{21}^{2}\leqslant {(95.74)}^{2}\ {\mathrm{mk}}^{2}$ at k = 0.256 h mpc-1 at z = 10.4. at z = 7.9, these limits are the most sensitive to date by over an order of magnitude. while we find evidence for residual systematics at low line-of-sight fourier k ∥ modes, at high k ∥ modes we find our data to be largely consistent with thermal noise, an indicator that the system could benefit from deeper integrations. the observed systematics could be due to radio frequency interference, cable subreflections, or residual instrumental cross-coupling, and warrant further study. this analysis emphasizes algorithms that have minimal inherent signal loss, although we do perform a careful accounting in a companion paper of the small forms of loss or bias associated with the pipeline. overall, these results are a promising first step in the development of a tuned, instrument-specific analysis pipeline for hera, particularly as phase ii construction is completed en route to reaching the full sensitivity of the experiment. | first results from hera phase i: upper limits on the epoch of reionization 21 cm power spectrum |
formation of cosmological solitons is generically accompanied by production of gravitational waves (gws), with a universal gw background expected at frequency scales below that of non-linear dynamics. beginning with a general phenomenological description of gws associated with soliton formation, we demonstrate that universal gw background from axion-like particle (alp) solitonic oscillons provides a viable interpretation to the recent nanograv 15 year pulsar timing array data, which does not suffer from the overproduction of primordial black holes. we show that pulsar timing array data displays preference for models where formed solitons do not strongly interact or cluster. coincidence observations with nancy roman telescope will allow to discriminate between distinct scenarios of cosmological solitons. | axion universal gravitational wave interpretation of pulsar timing array data |
we propose a relativistic gravitational theory leading to modified newtonian dynamics, a paradigm that explains the observed universal galactic acceleration scale and related phenomenology. we discuss phenomenological requirements leading to its construction and demonstrate its agreement with the observed cosmic microwave background and matter power spectra on linear cosmological scales. we show that its action expanded to second order is free of ghost instabilities and discuss its possible embedding in a more fundamental theory. | new relativistic theory for modified newtonian dynamics |
we derive analytic bounds on the shape of the primordial power spectrum in the context of single-field inflation. in particular, the steepest possible growth has a spectral index of ns - 1 = 4 once transients have died down. its primary implication is that any constraint on the power spectrum at a particular scale can be extrapolated to an upper bound over an extended range of scales. this is important for models which generate relics due to an enhanced amplitude of the primordial scalar perturbations, such as primordial black holes. in order to generate them, the power spectrum needs to grow many orders of magnitude larger than its observed value on cmb scales—typically achieved through a phase of ultra slow-roll inflation—and is thus subject to additional constraints at small scales. we plot all relevant constraints including cmb spectral distortions and gravitational waves sourced by scalar perturbations at second order. we show how this limits the allowed mass of pbhs, especially for the large masses of interest following recent detections by ligo and prospects for constraining them further with future observations. we show that any transition from approximately constant epsilon slow-roll inflation to a phase where the power spectrum rapidly rises necessarily implies an intervening dip in power. we also show how to reconstruct a potential that can reproduce an arbitrary time-varying epsilon, offering a complementary perspective on how ultra slow-roll can be achieved. | steepest growth of the power spectrum and primordial black holes |
using some of the latest cosmological data sets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, mν, within the assumption of a background flat λ cdm cosmology. in the most conservative scheme, combining planck cosmic microwave background temperature anisotropies and baryon acoustic oscillations (bao) data, as well as the up-to-date constraint on the optical depth to reionization (τ ), the tightest 95% confidence level upper bound we find is mν<0.151 ev . the addition of planck high-ℓ polarization data, which, however, might still be contaminated by systematics, further tightens the bound to mν<0.118 ev . a proper model comparison treatment shows that the two aforementioned combinations disfavor the inverted hierarchy at ∼64 % c .l . and ∼71 % c .l . , respectively. in addition, we compare the constraining power of measurements of the full-shape galaxy power spectrum versus the bao signature, from the boss survey. even though the latest boss full-shape measurements cover a larger volume and benefit from smaller error bars compared to previous similar measurements, the analysis method commonly adopted results in their constraining power still being less powerful than that of the extracted bao signal. our work uses only cosmological data; imposing the constraint mν>0.06 ev from oscillations data would raise the quoted upper bounds by o (0.1 σ ) and would not affect our conclusions. | unveiling ν secrets with cosmological data: neutrino masses and mass hierarchy |
we report on the discovery of frb 20200120e, a repeating fast radio burst (frb) with a low dispersion measure (dm) detected by the canadian hydrogen intensity mapping experiment frb project. the source dm of 87.82 pc cm-3 is the lowest recorded from an frb to date, yet it is significantly higher than the maximum expected from the milky way interstellar medium in this direction (∼50 pc cm-3). we have detected three bursts and one candidate burst from the source over the period 2020 january-november. the baseband voltage data for the event on 2020 january 20 enabled a sky localization of the source to within ≃14 arcmin2 (90% confidence). the frb localization is close to m81, a spiral galaxy at a distance of 3.6 mpc. the frb appears on the outskirts of m81 (projected offset ∼20 kpc) but well inside its extended h i and thick disks. we empirically estimate the probability of a chance coincidence with m81 to be <10-2. however, we cannot reject a milky way halo origin for the frb. within the frb localization region, we find several interesting cataloged m81 sources and a radio point source detected in the very large array sky survey. we search for prompt x-ray counterparts in swift burst alert telescope and fermi/gbm data, and, for two of the frb 20200120e bursts, we rule out coincident sgr 1806-20-like x-ray bursts. due to the proximity of frb 20200120e, future follow-up for prompt multiwavelength counterparts and subarcsecond localization could be constraining of proposed frb models. | a nearby repeating fast radio burst in the direction of m81 |
we propose a novel enhancement mechanism of the curvature perturbations in the nonminimal derivative coupling inflation model with a coupling parameter related to the inflaton field. by considering a special form of the coupling parameter as a function of the inflaton, a period of ultra-slow-roll inflation can be realized due to the gravitationally enhanced friction, and the resulting power spectrum of the curvature perturbations has a sharp peak, which is large enough to produce the primordial black holes. under this mechanism, we can easily obtain a sharp mass spectrum of primordial black holes around specific masses such as o (10 ) m⊙ , o (10-5) m⊙ , and o (10-12) m⊙ , which can explain the ligo events, the ultrashort-timescale microlensing events in ogle data, and the most of dark matter, respectively. | primordial black holes from inflation with nonminimal derivative coupling |
the investigation of primordial non-gaussianities holds immense importance in testing the inflation paradigm and shedding light on the physics of the early universe. in this study, we conduct the first complete analysis of scalar-induced gravitational waves (sigws) by simultaneously incorporating the local-type non-gaussianities $f_{\mathrm{nl}}$ and $g_{\mathrm{nl}}$. to achieve this, we develop a feynman-like diagrammatic technique and derive semi-analytic formulas for both the energy-density fraction spectrum and the angular power spectrum. for the energy-density fraction spectrum, we meticulously analyze all the relevant feynman-like diagrams, systematically determining their contributions to the spectrum in an order-by-order fashion. as for the angular power spectrum, our focus lies on the initial inhomogeneities that arise from the coupling between short-wavelength and long-wavelength modes due to primordial non-gaussianities. these inhomogeneities give rise to anisotropies in sigws. our analysis reveals that this spectrum exhibits a typical multipole dependence, characterized by $\tilde{c}_{\ell}\propto[\ell(\ell+1)]^{-1}$. this dependence plays a crucial role in distinguishing between different sources of gravitational waves. moreover, depending on the model parameters, significant anisotropies of $\tilde{c}_{\ell}\sim10^{-3}$ can be achieved. additionally, we demonstrate that the degeneracies in the model parameters can be broken. the findings of our study underscore the power of this spectrum as a robust probe for investigating primordial non-gaussianities and exploring the physics of the early universe through gravitational-wave observations. furthermore, the theoretical predictions derived from our research can be experimentally tested using space-borne gravitational-wave detectors and pulsar timing arrays. | complete analysis of scalar-induced gravitational waves and primordial non-gaussianities $f_{\\mathrm{nl}}$ and $g_{\\mathrm{nl}}$ |
we revisit the one-loop correction in curvature perturbation power spectrum in models of single field inflation which undergo a phase of ultra slow-roll (usr) inflation. we include the contributions from both the cubic and quartic interaction hamiltonians and calculate the one-loop corrections on the spectrum of the cmb scale modes from the small scale modes which leave the horizon during the usr phase. it is shown that the amplitude of one-loop corrections depends on the sharpness of the transition from the usr phase to the final slow-roll phase. for an arbitrarily sharp transition, the one-loop correction becomes arbitrarily large, invalidating the perturbative treatment of the analysis. we speculate that for a mild transition, the large one-loop corrections are washed out during the subsequent evolution after the usr phase. the implications for primordial black holes formation are briefly reviewed. | one-loop corrections in power spectrum in single field inflation |
the event horizon telescope has recently provided the first image of the dark shadow around the supermassive black hole m87*. the observation of a highly circular shadow provides strong limits on deviations of m87*'s quadrupole moment from the kerr value. we show that the absence of such a deviation can be used to constrain the physics of extra dimensions of spacetime. focusing on the randall-sundrum ads5 brane-world scenario, we show that the observation of m87*'s dark shadow sets the limit ℓ≲170 au , where ℓ is the ads5 curvature radius. this limit is among the first quantitative constraints on exotic physics obtained from the extraordinary first ever image of the dark shadow of a black hole. | hunting for extra dimensions in the shadow of m87* |
we report the detection of continuous positional and polarization changes of the compact source sgra* in high states ("flares") of its variable near-infrared emission with the near-infrared gravity-very large telescope interferometer (vlti) beam-combining instrument. in three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 μas over a few tens of minutes, corresponding to about 30% the speed of light. at the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(±15) min period as that of the centroid motions. modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized "hot spot" of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. this corresponds to the region just outside the innermost, stable, prograde circular orbit (isco) of a schwarzschild-kerr black hole, or near the retrograde isco of a highly spun-up kerr hole. the polarization signature is consistent with orbital motion in a strong poloidal magnetic field. the data are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/618/l10 | detection of orbital motions near the last stable circular orbit of the massive black hole sgra* |
we construct an updated extended compilation of distinct (but possibly correlated) f σ8(z ) redshift space distortion (rsd) data published between 2006 and 2018. it consists of 63 datapoints and is significantly larger than previously used similar data sets. after fiducial model correction we obtain the best fit ω0 m-σ8 λ cdm parameters and show that they are at a 5 σ tension with the corresponding planck15 /λ cdm values. introducing a nontrivial covariance matrix correlating randomly 20% of the rsd datapoints has no significant effect on the above tension level. we show that the tension disappears (becomes less than 1 σ ) when a subsample of the 20 most recently published data is used. a partial cause for this reduced tension is the fact that more recent data tend to probe higher redshifts (with higher errorbars) where there is degeneracy among different models due to matter domination. allowing for a nontrivial evolution of the effective newton's constant as geff(z )/gn=1 +ga(z/1+z ) 2-ga(z/1+z ) 4 (ga is a parameter) and fixing a planck15 /λ cdm background we find ga=-0.91 ±0.17 from the full f σ8 data set while the 20 earliest and 20 latest datapoints imply ga=-1.28-0.26+0.28 and ga=-0.4 3-0.41+0.46 respectively. thus, the more recent f σ8 data appear to favor gr in contrast to earlier data. finally, we show that the parametrization f σ8(z )=λ σ8ω (z )γ/(1 +z )β provides an excellent fit to the solution of the growth equation for both gr (ga=0 ) and modified gravity (ga≠0 ). | evolution of the f σ8 tension with the planck15 /λ cdm determination and implications for modified gravity theories |
we conduct large scale numerical simulations of gravitational wave production at a first-order vacuum phase transition. we find a power law for the gravitational wave power spectrum at high wave number which falls off as k-1.5 rather than the k-1 produced by the envelope approximation. the peak of the power spectrum is shifted to slightly lower wave numbers from that of the envelope approximation. the envelope approximation reproduces our results for the peak power less well, agreeing only to within an order of magnitude. after the bubbles finish colliding, the scalar field oscillates around the true vacuum. an additional feature is produced in the uv of the gravitational wave power spectrum, and this continues to grow linearly until the end of our simulation. the additional feature peaks at a length scale close to the bubble wall thickness and is shown to have a negligible contribution to the energy in gravitational waves, providing the scalar field mass is much smaller than the planck mass. | gravitational waves from vacuum first-order phase transitions: from the envelope to the lattice |
dark matter interactions with electrons or protons during the early universe leave imprints on the cosmic microwave background and the matter power spectrum, and can be probed through cosmological and astrophysical observations. these interactions lead to momentum and heat exchange between the ordinary and dark matter components, which in turn results in a transfer of pressure from the ordinary to the dark matter. we explore these interactions using a diverse suite of data: cosmic microwave background anisotropies, baryon acoustic oscillations, the lyman- α forest, and the abundance of milky-way subhalos. we derive constraints using model-independent parameterizations of the dark matter-electron and dark matter-proton interaction cross sections and map these constraints onto concrete dark matter models. our constraints are complementary to other probes of dark matter interactions with ordinary matter, such as direct detection, big bang nucleosynthesis, various astrophysical systems, and accelerator-based experiments. they exclude sufficiently large cross sections for a large range of dark matter masses, which cannot be accessed by direct-detection experiments due to the overburden from the earth's atmosphere or crust. | cosmological constraints on dark matter interactions with ordinary matter |
the concordance model (λ cold dark matter (λcdm) model, where λ is the cosmological constant) reproduces the main current cosmological observations1-4 assuming the validity of general relativity at all scales and epochs and the presence of cdm and of λ, equivalent to dark energy with a constant density in space and time. however, the λcdm model is poorly tested in the redshift interval between the farthest observed type ia supernovae5 and the cosmic microwave background. we present measurements of the expansion rate of the universe based on a hubble diagram of quasars. quasars are the most luminous persistent sources in the universe, observed up to redshifts of z ≈ 7.5 (refs. 6,7). we estimate their distances following a method developed by our group8-10, based on the x-ray and ultraviolet emission of the quasars. the distance modulus/redshift relation of quasars at z < 1.4 is in agreement with that of supernovae and with the concordance model. however, a deviation from the λcdm model emerges at higher redshift, with a statistical significance of ~4σ. if an evolution of the dark energy equation of state is allowed, the data suggest dark energy density increasing with time. | cosmological constraints from the hubble diagram of quasars at high redshifts |
we present the methodology for and detail the implementation of the dark energy survey (des) 3x2pt des year 1 (y1) analysis, which combines configuration-space two-point statistics from three different cosmological probes: cosmic shear, galaxy-galaxy lensing, and galaxy clustering, using data from the first year of des observations. we have developed two independent modeling pipelines and describe the code validation process. we derive expressions for analytical real-space multi-probe covariances, and describe their validation with numerical simulations. we stress-test the inference pipelines in simulated likelihood analyses that vary 6-7 cosmology parameters plus 20 nuisance parameters and precisely resemble the analysis to be presented in the des 3x2pt analysis paper, using a variety of simulated input data vectors with varying assumptions. we find that any disagreement between pipelines leads to changes in assigned likelihood $\delta \chi^2 \le 0.045$ with respect to the statistical error of the des y1 data vector. we also find that angular binning and survey mask do not impact our analytic covariance at a significant level. we determine lower bounds on scales used for analysis of galaxy clustering (8 mpc$~h^{-1}$) and galaxy-galaxy lensing (12 mpc$~h^{-1}$) such that the impact of modeling uncertainties in the non-linear regime is well below statistical errors, and show that our analysis choices are robust against a variety of systematics. these tests demonstrate that we have a robust analysis pipeline that yields unbiased cosmological parameter inferences for the flagship 3x2pt des y1 analysis. we emphasize that the level of independent code development and subsequent code comparison as demonstrated in this paper is necessary to produce credible constraints from increasingly complex multi-probe analyses of current data. | dark energy survey year 1 results: multi-probe methodology and simulated likelihood analyses |
astrophysical observations spanning dwarf galaxies to galaxy clusters indicate that dark matter (dm) halos are less dense in their central regions compared to expectations from collisionless dm n -body simulations. using detailed fits to dm halos of galaxies and clusters, we show that self-interacting dm (sidm) may provide a consistent solution to the dm deficit problem across all scales, even though individual systems exhibit a wide diversity in halo properties. since the characteristic velocity of dm particles varies across these systems, we are able to measure the self-interaction cross section as a function of kinetic energy and thereby deduce the sidm particle physics model parameters. our results prefer a mildly velocity-dependent cross section, from σ /m ≈2 cm2/g on galaxy scales to σ /m ≈0.1 cm2/g on cluster scales, consistent with the upper limits from merging clusters. our results dramatically improve the constraints on sidm models and may allow the masses of both dm and dark mediator particles to be measured even if the dark sector is completely hidden from the standard model, which we illustrate for the dark photon model. | dark matter halos as particle colliders: unified solution to small-scale structure puzzles from dwarfs to clusters |
we present x-ray source catalogs for the ≈7 ms exposure of the chandra deep field-south (cdf-s), which covers a total area of 484.2 arcmin2. utilizing wavdetect for initial source detection and acis extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three x-ray bands: 0.5-7.0 kev, 0.5-2.0 kev, and 2-7 kev. a supplementary source catalog is also provided, including 47 lower-significance sources that have bright ({k}s≤slant 23) near-infrared counterparts. we identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. based on the x-ray and multiwavelength properties, we identify 711 active galactic nuclei (agns) from the main-catalog sources. compared to the previous ≈4 ms cdf-s catalogs, 291 of the main-catalog sources are new detections. we have achieved unprecedented x-ray sensitivity with average flux limits over the central ≈1 arcmin2 region of ≈1.9 × 10-17, 6.4 × 10-18, and 2.7 × 10-17 erg cm-2 s-1 in the three x-ray bands, respectively. we provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the x-ray source population at the faintest 0.5-2.0 kev flux levels. the highest x-ray source density reaches ≈50,500 deg-2, and 47% ± 4% of these sources are agns (≈23,900 deg-2). | the chandra deep field-south survey: 7 ms source catalogs |
we consider the simplest possibility for a model of particle dark matter in which dark matter has only gravitational interaction with the standard model sector. even in such a case, it is known that the gravitational particle production in an expanding universe may lead to a correct relic abundance depending on the ination scale and the mass of dark matter particle. we provide a comprehensive and systematic analysis of the gravitational particle production of fermionic and vectorial dark matter, and emphasize that particles which are much heavier than the hubble parameter but lighter than inaton can also be produced abundantly. | production of purely gravitational dark matter: the case of fermion and vector boson |
we consider the possibility of an interaction in the dark sector in the presence of massive neutrinos and study the observational constraints on three different scenarios of massive neutrinos using the most recent cosmic microwave background anisotropy data in combination with type ia supernovae, baryon acoustic oscillations, and hubble parameter measurements. when a sterile neutrino is introduced into the interacting dark sector scenario in addition to the standard model prediction of neutrinos, we find that the coupling parameter is nonzero at a 2 σ confidence level. the interaction model with a sterile neutrino is also found to be a promising one to alleviate the current tension on the hubble constant. we do not find the evidence for a coupling in the dark sector when the possibility of a sterile neutrino is discarded. | probing the interaction between dark matter and dark energy in the presence of massive neutrinos |
we report on the discovery and analysis of bursts from nine new repeating fast radio burst (frb) sources found using the canadian hydrogen intensity mapping experiment (chime) telescope. these sources span a dispersion measure (dm) range of 195-1380 pc cm-3. we detect two bursts from three of the new sources, three bursts from four of the new sources, four bursts from one new source, and five bursts from one new source. we determine sky coordinates of all sources with uncertainties of ∼10'. we detect faraday rotation measures (rms) for two sources, with values -20(1) and -499.8(7) rad m-2, that are substantially lower than the rm derived from bursts emitted by frb 121102. we find that the dm distribution of our events, combined with the nine other repeaters discovered by chime/frb, is indistinguishable from that of thus far non-repeating chime/frb events. however, as previously reported, the burst widths appear statistically significantly larger than the thus far non-repeating chime/frb events, further supporting the notion of inherently different emission mechanisms and/or local environments. these results are consistent with previous work, though are now derived from 18 repeating sources discovered by chime/frb during its first year of operation. we identify candidate galaxies that may contain frb 190303.j1353+48 (dm = 222.4 pc cm-3). | nine new repeating fast radio burst sources from chime/frb |
we perform a joint analysis of the counts and weak lensing signal of redmapper clusters selected from the dark energy survey (des) year 1 dataset. our analysis uses the same shear and source photometric redshifts estimates as were used in the des combined probes analysis. our analysis results in surprisingly low values for s8=σ8(ωm/0.3 )0.5=0.65 ±0.04 , driven by a low matter density parameter, ωm=0.17 9-0.038+0.031, with σ8-ωm posteriors in 2.4 σ tension with the des y1 3x2pt results, and in 5.6 σ with the planck cmb analysis. these results include the impact of post-unblinding changes to the analysis, which did not improve the level of consistency with other data sets compared to the results obtained at the unblinding. the fact that multiple cosmological probes (supernovae, baryon acoustic oscillations, cosmic shear, galaxy clustering and cmb anisotropies), and other galaxy cluster analyses all favor significantly higher matter densities suggests the presence of systematic errors in the data or an incomplete modeling of the relevant physics. cross checks with x-ray and microwave data, as well as independent constraints on the observable-mass relation from sunyaev-zeldovich selected clusters, suggest that the discrepancy resides in our modeling of the weak lensing signal rather than the cluster abundance. repeating our analysis using a higher richness threshold (λ ≥30 ) significantly reduces the tension with other probes, and points to one or more richness-dependent effects not captured by our model. | dark energy survey year 1 results: cosmological constraints from cluster abundances and weak lensing |
homogeneous oscillations of the inflaton after inflation can be unstable to small spatial perturbations even without coupling to other fields. we show that for inflaton potentials ∝|ϕ |2n near |ϕ |=0 and flatter beyond some |ϕ |=m , the inflaton condensate oscillations can lead to self-resonance, followed by its complete fragmentation. we find that for nonquadratic minima (n >1 ), shortly after backreaction, the equation of state parameter, w →1 /3 . if m ≪mpl, radiation domination is established within less than an e -fold of expansion after the end of inflation. in this case self-resonance is efficient and the condensate fragments into transient, localised spherical objects which are unstable and decay, leaving behind them a virialized field with mean kinetic and gradient energies much greater than the potential energy. this end-state yields w =1 /3 . when m ∼mpl we observe slow and steady, self-resonance that can last many e -folds before backreaction eventually shuts it off, followed by fragmentation and w →1 /3 . we provide analytical estimates for the duration to w →1 /3 after inflation, which can be used as an upper bound (under certain assumptions) on the duration of the transition between the inflationary and the radiation dominated states of expansion. this upper bound can reduce uncertainties in cmb observables such as the spectral tilt ns, and the tensor-to-scalar ratio r . for quadratic minima (n =1 ), w →0 regardless of the value of m . this is because when m ≪mpl, long-lived oscillons form within an e -fold after inflation, and collectively behave as pressureless dust thereafter. for m ∼mpl, the self-resonance is inefficient and the condensate remains intact (ignoring long-term gravitational clustering) and keeps oscillating about the quadratic minimum, again implying w =0 . | self-resonance after inflation: oscillons, transients, and radiation domination |
the polarized thermal emission from diffuse galactic dust is the main foreground present in measurements of the polarization of the cosmic microwave background (cmb) at frequencies above 100 ghz. in this paper we exploit the uniqueness of the planck hfi polarization data from 100 to 353 ghz to measure the polarized dust angular power spectra cℓee and cℓbb over the multipole range 40 <ℓ< 600 well away from the galactic plane. these measurements will bring new insights into interstellar dust physics and allow a precise determination of the level of contamination for cmb polarization experiments. despite the non-gaussian and anisotropic nature of galactic dust, we show that general statistical properties of the emission can be characterized accurately over large fractions of the sky using angular power spectra. the polarization power spectra of the dust are well described by power laws in multipole, cℓ ∝ ℓα, with exponents αee,bb = -2.42 ± 0.02. the amplitudes of the polarization power spectra vary with the average brightness in a way similar to the intensity power spectra. the frequency dependence of the dust polarization spectra is consistent with modified blackbody emission with βd = 1.59 and td = 19.6 k down to the lowest planck hfi frequencies. we find a systematic difference between the amplitudes of the galactic b- and e-modes, cℓbb/cℓee = 0.5. we verify that these general properties are preserved towards high galactic latitudes with low dust column densities. we show that even in the faintest dust-emitting regions there are no "clean" windows in the sky where primordial cmb b-mode polarization measurements could be made without subtraction of foreground emission. finally, we investigate the level of dust polarization in the specific field recently targeted by the bicep2 experiment. extrapolation of the planck 353 ghz data to 150 ghz gives a dust power 𝒟ℓbb ≡ ℓ(ℓ+1)cℓbb/(2π) of 1.32 × 10-2 μkcmb2 over the multipole range of the primordial recombination bump (40 <ℓ< 120); the statistical uncertainty is ± 0.29 × 10-2 μkcmb2 and there is an additional uncertainty (+0.28, -0.24) × 10-2 μkcmb2 from the extrapolation. this level is the same magnitude as reported by bicep2 over this ℓ range, which highlights the need for assessment of the polarized dust signal even in the cleanest windows of the sky. | planck intermediate results. xxx. the angular power spectrum of polarized dust emission at intermediate and high galactic latitudes |
we study the contribution to the qcd axion dark matter abundance that is produced by string defects during the so-called scaling regime. clear evidence of scaling violations is found, the most conservative extrapolation of which strongly suggests a large number of axions from strings. in this regime, nonlinearities at around the qcd scale are shown to play an important role in determining the final abundance. the overall result is a lower bound on the qcd axion mass in the post-inflationary scenario that is substantially stronger than the naive one from misalignment. adsx-1075: | more axions from strings |
cosmic string networks offer one of the best prospects for detection of cosmological gravitational waves (gws). the combined incoherent gw emission of a large number of string loops leads to a stochastic gw background (sgwb), which encodes the properties of the string network. in this paper we analyze the ability of the laser interferometer space antenna (lisa) to measure this background, considering leading models of the string networks. we find that lisa will be able to probe cosmic strings with tensions gμ gtrsim 𝒪(10-17), improving by about 6 orders of magnitude current pulsar timing arrays (pta) constraints, and potentially 3 orders of magnitude with respect to expected constraints from next generation pta observatories. we include in our analysis possible modifications of the sgwb spectrum due to different hypotheses regarding cosmic history and the underlying physics of the string network. these include possible modifications in the sgwb spectrum due to changes in the number of relativistic degrees of freedom in the early universe, the presence of a non-standard equation of state before the onset of radiation domination, or changes to the network dynamics due to a string inter-commutation probability less than unity. in the event of a detection, lisa's frequency band is well-positioned to probe such cosmic events. our results constitute a thorough exploration of the cosmic string science that will be accessible to lisa. | probing the gravitational wave background from cosmic strings with lisa |
we propose two-dimensional materials as targets for direct detection of dark matter. using graphene as an example, we focus on the case where dark matter scattering deposits sufficient energy on a valence-band electron to eject it from the target. we show that the sensitivity of graphene to dark matter of mev to gev mass can be comparable, for similar exposure and background levels, to that of semiconductor targets such as silicon and germanium. moreover, a two-dimensional target is an excellent directional detector, as the ejected electron retains information about the angular dependence of the incident dark matter particle. this proposal can be implemented by the ptolemy experiment, presenting for the first time an opportunity for directional detection of sub-gev dark matter. | directional detection of dark matter with two-dimensional targets |
although cosmic microwave background and large scale structure probe the largest scales of our universe with ever-increasing precision, our knowledge about the smaller scales is still very limited other than the bounds on primordial black holes (pbhs). we show that the statistical properties of the small scale quantum fluctuations can be probed via the stochastic gravitational wave (gw) background, which is induced as the scalar modes reenter the horizon. we found that even if scalar curvature fluctuations have a subdominant non-gaussian component, these non-gaussian perturbations can source a dominant portion of the induced gws. moreover, the gws sourced by non-gaussian scalar fluctuations peak at a higher frequency and this can result in distinctive observational signatures. if the induced gw background is detected, but not the signatures arising from the non-gaussian component, ζ =ζg+fnlζg2 , this translates into bounds on fnl depending on the amplitude and the width of the gw signal. the results are independent of the fact that whether pbhs are dark matter or a completely negligible part of the current energy density. | imprints of primordial non-gaussianity on gravitational wave spectrum |
the study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (cmb) polarization in the quest for the curl-like b-mode polarization from primordial gravitational waves and the low-multipole e-mode polarization associated with the reionization of the universe. we used the new planck pr3 maps to characterize galactic dust emission at high latitudes as a foreground to the cmb polarization and use end-to-end simulations to compute uncertainties and assess the statistical significance of our measurements. we present planck ee, bb, and te power spectra of dust polarization at 353 ghz for a set of six nested high-galactic-latitude sky regions covering from 24 to 71% of the sky. we present power-law fits to the angular power spectra, yielding evidence for statistically significant variations of the exponents over sky regions and a difference between the values for the ee and bb spectra, which for the largest sky region are αee = −2.42 ± 0.02 and αbb = −2.54 ± 0.02, respectively. the spectra show that the te correlation and e/b power asymmetry discovered by planck extend to low multipoles that were not included in earlier planck polarization papers due to residual data systematics. we also report evidence for a positive tb dust signal. combining data from planck and wmap, we have determined the amplitudes and spectral energy distributions (seds) of polarized foregrounds, including the correlation between dust and synchrotron polarized emission, for the six sky regions as a function of multipole. this quantifies the challenge of the component-separation procedure that is required for measuring the low-ℓ reionization cmb e-mode signal and detecting the reionization and recombination peaks of primordial cmb b modes. the sed of polarized dust emission is fit well by a single-temperature modified black-body emission law from 353 ghz to below 70 ghz. for a dust temperature of 19.6 k, the mean dust spectral index for dust polarization is βdp = 1.53±0.02. the difference between indices for polarization and total intensity is βdp−βdi = 0.05±0.03. by fitting multi-frequency cross-spectra between planck data at 100, 143, 217, and 353 ghz, we examine the correlation of the dust polarization maps across frequency. we find no evidence for a loss of correlation and provide lower limits to the correlation ratio that are tighter than values we derive from the correlation of the 217- and 353 ghz maps alone. if the planck limit on decorrelation for the largest sky region applies to the smaller sky regions observed by sub-orbital experiments, then frequency decorrelation of dust polarization might not be a problem for cmb experiments aiming at a primordial b-mode detection limit on the tensor-to-scalar ratio r ≃ 0.01 at the recombination peak. however, the planck sensitivity precludes identifying how difficult the component-separation problem will be for more ambitious experiments targeting lower limits on r. | planck 2018 results. xi. polarized dust foregrounds |
this white paper provides a comprehensive review of our present understanding of experimental neutrino anomalies that remain unresolved, charting the progress achieved over the last decade at the experimental and phenomenological level, and sets the stage for future programmatic prospects in addressing those anomalies. it is purposed to serve as a guiding and motivational "encyclopedic" reference, with emphasis on needs and options for future exploration that may lead to the ultimate resolution of the anomalies. we see the main experimental, analysis, and theory-driven thrusts that will be essential to achieving this goal being: 1) cover all anomaly sectors -- given the unresolved nature of all four canonical anomalies, it is imperative to support all pillars of a diverse experimental portfolio, source, reactor, decay-at-rest, decay-in-flight, and other methods/sources, to provide complementary probes of and increased precision for new physics explanations; 2) pursue diverse signatures -- it is imperative that experiments make design and analysis choices that maximize sensitivity to as broad an array of these potential new physics signatures as possible; 3) deepen theoretical engagement -- priority in the theory community should be placed on development of standard and beyond standard models relevant to all four short-baseline anomalies and the development of tools for efficient tests of these models with existing and future experimental datasets; 4) openly share data -- fluid communication between the experimental and theory communities will be required, which implies that both experimental data releases and theoretical calculations should be publicly available; and 5) apply robust analysis techniques -- appropriate statistical treatment is crucial to assess the compatibility of data sets within the context of any given model. | white paper on light sterile neutrino searches and related phenomenology |
despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, λ cdm. this is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the cmb and on small scales, and the predictivity and testability of the inflationary paradigm. in this paper, we summarize the current status of λ cdm as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. while the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled. | beyond λ cdm: problems, solutions, and the road ahead |
we present a novel mechanism for gravitational wave generation in the early universe. light spectator scalar fields during inflation can acquire a blue-tilted power spectrum due to stochastic effects. we show that this effect can lead to large curvature perturbations at small scales (induced by the spectator field fluctuations) while maintaining the observed, slightly red-tilted curvature perturbations at large cosmological scales (induced by the inflaton fluctuations). along with other observational signatures, such as enhanced dark matter substructure, large curvature perturbations can induce a stochastic gravitational wave background (sgwb). the predicted strength of sgwb in our scenario, $\omega_{\rm gw}h^2 \simeq 10^{-20} - 10^{-15}$, can be observed with future detectors, operating between $10^{-5}$ hz and 10 hz. we note that, in order to accommodate the newly reported nanograv observation, one could consider the same class of spectator models. at the same time, one would need to go beyond the simple benchmark considered here and consider a regime in which a misalignment contribution is also important. | gravitational waves from stochastic scalar fluctuations |
we present a non-perturbative method for calculating the abundance of primordial black holes given an arbitrary one-point probability distribution function for the primordial curvature perturbation, $p(\zeta)$ ?> . a non-perturbative method is essential when considering non-gaussianities that cannot be treated using a conventional perturbative expansion. to determine the full statistics of the density field, we relate ζ to a gaussian field by equating the cumulative distribution functions. we consider two examples: a specific local-type non-gaussian distribution arising from ultra slow roll models, and a general piecewise model for $p(\zeta)$ ?> with an exponential tail. we demonstrate that the enhancement of primordial black hole formation is due to the intermediate regime, rather than the far tail. we also show that non-gaussianity can have a significant impact on the shape of the primordial black hole mass distribution. | non-perturbative non-gaussianity and primordial black holes |
final results are reported from operation of the pico-60 c3f8 dark matter detector, a bubble chamber filled with 52 kg of c3 f8 located in the snolab underground laboratory. the chamber was operated at thermodynamic thresholds as low as 1.2 kev without loss of stability. a new blind 1404-kg-day exposure at 2.45 kev threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 kev. this increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. these results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (wimp)-proton spin-dependent cross section at 3.2 ×1 0-41 cm2 for a 25 gev wimp, improving on previous pico results for 3-5 gev wimps by an order of magnitude. | dark matter search results from the complete exposure of the pico-60 c3f8 bubble chamber |
we present new limits on an isotropic stochastic gravitational-wave background (gwb) using a six pulsar data set spanning 18 yr of observations from the 2015 european pulsar timing array data release. performing a bayesian analysis, we fit simultaneously for the intrinsic noise parameters for each pulsar, along with common correlated signals including clock, and solar system ephemeris errors, obtaining a robust 95 per cent upper limit on the dimensionless strain amplitude a of the background of a < 3.0 × 10-15 at a reference frequency of 1 yr-1 and a spectral index of 13/3, corresponding to a background from inspiralling supermassive black hole binaries, constraining the gw energy density to ωgw(f)h2 < 1.1 × 10-9 at 2.8 nhz. we also present limits on the correlated power spectrum at a series of discrete frequencies, and show that our sensitivity to a fiducial isotropic gwb is highest at a frequency of ∼5 × 10-9 hz. finally, we discuss the implications of our analysis for the astrophysics of supermassive black hole binaries, and present 95 per cent upper limits on the string tension, gμ/c2, characterizing a background produced by a cosmic string network for a set of possible scenarios, and for a stochastic relic gwb. for a nambu-goto field theory cosmic string network, we set a limit gμ/c2 < 1.3 × 10-7, identical to that set by the planck collaboration, when combining planck and high-ℓ cosmic microwave background data from other experiments. for a stochastic relic background, we set a limit of ω ^relic_gw(f)h^2<1.2 × 10^{-9}, a factor of 9 improvement over the most stringent limits previously set by a pulsar timing array. | european pulsar timing array limits on an isotropic stochastic gravitational-wave background |
the answer is yes. we indeed find that interacting dark energy can alleviate the current tension on the value of the hubble constant h0 between the cosmic microwave background anisotropies constraints obtained from the planck satellite and the recent direct measurements reported by riess et al. 2016. the combination of these two data sets points toward a nonzero dark matter-dark energy coupling ξ at more than two standard deviations, with ξ =-0.2 6-0.12+0.16 at 95% c.l., i.e. with a moderate evidence for interacting dark energy with an odds ratio of 6 ∶1 respect to a non interacting cosmological constant. however the h0 tension is better solved when the equation of state of the interacting dark energy component is allowed to freely vary, with a phantomlike equation of state w =-1.185 ±0.064 (at 68% c.l.), ruling out the pure cosmological constant case, w =-1 , again at more than two standard deviations. when planck data are combined with external datasets, as bao, jla supernovae ia luminosity distances, cosmic shear or lensing data, we find perfect consistency with the cosmological constant scenario and no compelling evidence for a dark matter-dark energy coupling. | can interacting dark energy solve the h0 tension? |
we study the implications of the recently proposed trans-planckian censorship conjecture (tcc) for early universe cosmology and in particular inflationary cosmology. the tcc leads to the conclusion that if we want inflationary cosmology to provide a successful scenario for cosmological structure formation, the energy scale of inflation has to be lower than 109 gev . demanding the correct amplitude of the cosmological perturbations then forces the generalized slow-roll parameter ɛ of the model to be very small (<10-31). this leads to the prediction of a negligible amplitude of primordial gravitational waves. for slow-roll inflation models, it also leads to severe fine-tuning of initial conditions. | trans-planckian censorship and inflationary cosmology |
we analyse the clustering of the sloan digital sky survey iv extended baryon oscillation spectroscopic survey data release 16 luminous red galaxy sample (dr16 eboss lrg) in combination with the high redshift tail of the sloan digital sky survey iii baryon oscillation spectroscopic survey data release 12 (dr12 boss cmass). we measure the redshift space distortions (rsd) and also extract the longitudinal and transverse baryonic acoustic oscillation (bao) scale from the anisotropic power spectrum signal inferred from 377 458 galaxies between redshifts 0.6 and 1.0, with the effective redshift of zeff = 0.698 and effective comoving volume of $2.72\, {\rm gpc}^3$. after applying reconstruction, we measure the bao scale and infer dh(zeff)/rdrag = 19.30 ± 0.56 and dm(zeff)/rdrag = 17.86 ± 0.37. when we perform an rsd analysis on the pre-reconstructed catalogue on the monopole, quadrupole, and hexadecapole we find, dh(zeff)/rdrag = 20.18 ± 0.78, dm(zeff)/rdrag = 17.49 ± 0.52 and fσ8(zeff) = 0.454 ± 0.046. we combine both sets of results along with the measurements in configuration space and report the following consensus values: dh(zeff)/rdrag = 19.77 ± 0.47, dm(zeff)/rdrag = 17.65 ± 0.30 and fσ8(zeff) = 0.473 ± 0.044, which are in full agreement with the standard λcdm and gr predictions. these results represent the most precise measurements within the redshift range 0.6 ≤ z ≤ 1.0 and are the culmination of more than 8 yr of sdss observations. | the completed sdss-iv extended baryon oscillation spectroscopic survey: measurement of the bao and growth rate of structure of the luminous red galaxy sample from the anisotropic power spectrum between redshifts 0.6 and 1.0 |
we present jwst extragalactic medium-band survey, the first public medium-band imaging survey carried out using jwst/nircam and niriss. these observations use ~2 and ~4 μm medium-band filters (nircam f182m, f210m, f430m, f460m, f480m; and niriss f430m and f480m in parallel) over 15.6 arcmin2 in the hubble ultra deep field (udf), thereby building on the deepest multiwavelength public data sets available anywhere on the sky. we describe our science goals, survey design, nircam and niriss image reduction methods, and describe our first data release of the science-ready mosaics, which reach 5σ point-source limits (ab mag) of ~29.3-29.4 in 2 μm filters and ~28.2-28.7 at 4 μm. our chosen filters create a jwst imaging survey in the udf that enables novel analysis of a range of spectral features potentially across the redshift range of 0.3 < z < 20, including paschen-α, hα+[n ii], and [o iii]+hβ emission at high spatial resolution. we find that our jwst medium-band imaging efficiently identifies strong line emitters (medium-band colors >1 mag) across redshifts 1.5 < z < 9.3, most prominently hα+[n ii] and [o iii]+hβ. we present our first data release including science-ready mosaics of each medium-band image available to the community, adding to the legacy value of past and future surveys in the udf. this survey demonstrates the power of medium-band imaging with jwst, informing future extragalactic survey strategies using jwst observations. | jems: a deep medium-band imaging survey in the hubble ultra deep field with jwst nircam and niriss |
we review conceptual aspects of inflationary scenarios able to produce primordial black holes by amplifying the size of curvature fluctuations to the level required to trigger black hole formation. we identify general mechanisms to do so, both for single- and multiple-field inflation. in single-field inflation, the spectrum of curvature fluctuations is enhanced by pronounced gradients of background quantities controlling the cosmological dynamics, which can induce brief phases of non-slow-roll inflationary evolution. in multiple-field inflation, the amplification occurs through appropriate couplings with additional sectors characterized by tachyonic instabilities that enhance the size of their fluctuations. as representative examples, we consider axion inflation and two-field models of inflation with rapid turns in field space. we develop our discussion in a pedagogical manner by including some of the most relevant calculations and by guiding the reader through the existing theoretical literature, emphasizing general themes common to several models. | inflation and primordial black holes |
the mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by planck in the context of the standard λcdm, known as the hubble tension, has become one of the most pressing problems in cosmology. a large number of amendments to the λcdm model have been proposed in order to solve this tension. many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing the sound horizon at recombination r⋆. we demonstrate here that any model which only reduces r⋆ can never fully resolve the hubble tension while remaining consistent with other cosmological datasets. we show explicitly that models which achieve a higher hubble constant with lower values of matter density ωmh2 run into tension with the observations of baryon acoustic oscillations, while models with larger ωmh2 develop tension with galaxy weak lensing data. | why reducing the cosmic sound horizon alone can not fully resolve the hubble tension |
ngc 4258 is a critical galaxy for establishing the extragalactic distance scale and estimating the hubble constant ({h}0). water masers in the nucleus of the galaxy orbit about its supermassive black hole, and very long baseline interferometric observations of their positions, velocities, and accelerations can be modeled to give a geometric estimate of the angular-diameter distance to the galaxy. we have improved the technique to obtain model parameter values, reducing both statistical and systematic uncertainties compared to previous analyses. we find the distance to ngc 4258 to be 7.576 ± 0.082 (stat.) ± 0.076 (sys.) mpc. using this as the sole source of calibration of the cepheid-sn ia distance ladder results in {h}0=72.0+/- 1.9 km s-1 mpc-1, and in concert with geometric distances from milky way parallaxes and detached eclipsing binaries in the lmc we find {h}0=73.5 +/- 1.4 km s-1 mpc-1. the improved distance to ngc 4258 also provides a new calibration of the tip of the red giant branch of {m}f814w=-4.01+/- 0.04 mag, with reduced systematic errors for the determination of {h}0 compared to the lmc-based calibration, because it is measured on the same hubble space telescope (hst) photometric system and through similarly low extinction as sn ia host halos. the result is {h}0=71.1+/- 1.9 km s-1 mpc-1, in good agreement with the result from the cepheid route, and there is no difference in {h}0 when using the same calibration from ngc 4258 and the same sn ia hubble diagram intercept to start and end both distance ladders. | an improved distance to ngc 4258 and its implications for the hubble constant |
the event horizon telescope image of the supermassive black hole in the galaxy m87 is dominated by a bright, unresolved ring. general relativity predicts that embedded within this image lies a thin "photon ring," which is composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole. the subrings approach the edge of the black hole "shadow," becoming exponentially narrower but weaker with increasing orbit number, with seemingly negligible contributions from high order subrings. here, we show that these subrings produce strong and universal signatures on long interferometric baselines. these signatures offer the possibility of precise measurements of black hole mass and spin, as well as tests of general relativity, using only a sparse interferometric array. | universal interferometric signatures of a black hole's photon ring |
it is known that the single-field inflation with a transient ultra-slow-roll phase can produce a large curvature perturbation at small scales for the formation of primordial black holes. in our previous work, we have considered quantum loop corrections to the curvature perturbation and found that the growth of these small-scale modes would affect the curvature perturbation at large scales probed by cosmic microwave background observation. in this work, we will further derive the constraints on the growing modes in the transition between the slow-roll and the ultra-slow-roll phases under the effect of the loop corrections. our results would help clarify the recent controversy on whether or not the primordial-black-hole formation from the single-field inflation is ruled out at one-loop level. | primordial perturbations from ultra-slow-roll single-field inflation with quantum loop effects |
we propose a new four-parameter entropy function that generalizes the tsallis, rényi, barrow, sharma-mittal, kaniadakis and loop quantum gravity entropies for suitable limits of the parameters. consequently, we address the early and late universe cosmology corresponding to the proposed four-parameter entropy function. as a result, it turns out that the entropic cosmology from the generalized entropy function can unify the early inflation to the late dark energy era of the universe. in such a unified scenario, we find that - (1) the inflation era is described by a quasi de-sitter evolution of the hubble parameter, which has an exit at around 58 e-folding number, (2) the inflationary observable quantities like the spectral index for primordial scalar perturbation and the tensor-to-scalar ratio are simultaneously compatible with the recent planck data, and (3) regarding the late time cosmology, the dark energy eos parameter is found to be consistent with the planck result for the same values of the entropy parameters that lead to the viable inflation during the early universe. furthermore, we show that the entropic cosmology from the proposed entropy function is equivalent to holographic cosmology, where the respective holographic cut-offs are determined in terms of either particle horizon and its derivative or future horizon and its derivative. | early and late universe holographic cosmology from a new generalized entropy |
we perform a blinded cosmology analysis with cosmic shear two-point correlation functions measured from more than 25 million galaxies in the hyper suprime-cam three-year shear catalog in four tomographic redshift bins ranging from 0.3 to 1.5. after conservative masking and galaxy selection, the survey covers 416 deg2 of the northern sky with an effective galaxy number density of 15 arcmin-2 over the four redshift bins. the 2pcfs adopted for cosmology analysis are measured in the angular range; 7.1 <θ /arcmin <56.6 for ξ+ and 31.2 <θ /arcmin <248 for ξ-, with a total signal-to-noise ratio of 26.6. we apply a conservative, wide, flat prior on the photometric redshift errors on the last two tomographic bins, and the relative magnitudes of the cosmic shear amplitude across four redshift bins allow us to calibrate the photometric redshift errors. with this flat prior on redshift errors, we find ωm=0.25 6-0.044+0.056 and s8≡σ8√{ωm/0.3 }=0.76 9-0.034+0.031 (both 68% c.i.) for a flat λ cold dark matter cosmology. we find, after unblinding, that our constraint on s8 is consistent with the fourier space cosmic shear and the 3 ×2 pt analyses on the same hsc dataset. we carefully study the potential systematics from astrophysical and systematic model uncertainties in our fiducial analysis using synthetic data, and report no biases (including projection bias in the posterior space) greater than 0.5 σ in the estimation of s8. our analysis hints that the mean redshifts of the two highest tomographic bins are higher than initially estimated. in addition, a number of consistency tests are conducted to assess the robustness of our analysis. comparing our result with planck-2018 cosmic microwave background observations, we find a ∼2 σ tension for the λ cdm model. | hyper suprime-cam year 3 results: cosmology from cosmic shear two-point correlation functions |
we analyse the large-scale clustering in fourier space of emission line galaxies (elg) from the data release 16 of the sloan digital sky survey iv extended baryon oscillation spectroscopic survey. the elg sample contains 173 736 galaxies covering 1170 deg2 in the redshift range 0.6 < z < 1.1. we perform a bao measurement from the post-reconstruction power spectrum monopole, and study redshift space distortions (rsd) in the first three even multipoles. photometric variations yield fluctuations of both the angular and radial survey selection functions. those are directly inferred from data, imposing integral constraints which we model consistently. the full data set has only a weak preference for a bao feature (1.4σ). at the effective redshift zeff = 0.845 we measure $d_{\rm v}(z_{\rm eff})/r_{\rm drag} = 18.33_{-0.62}^{+0.57}$ , with dv the volume-averaged distance and rdrag the comoving sound horizon at the drag epoch. in combination with the rsd measurement, at zeff = 0.85 we find $f\sigma _8(z_{\rm eff}) = 0.289_{-0.096}^{+0.085}$ , with f the growth rate of structure and σ8 the normalization of the linear power spectrum, $d_{\rm h}(z_{\rm eff})/r_{\rm drag} = 20.0_{-2.2}^{+2.4}$ and dm(zeff)/rdrag = 19.17 ± 0.99 with dh and dm the hubble and comoving angular distances, respectively. these results are in agreement with those obtained in configuration space, thus allowing a consensus measurement of fσ8(zeff) = 0.315 ± 0.095, $d_{\rm h}(z_{\rm eff})/r_{\rm drag} = 19.6_{-2.1}^{+2.2}$ and dm(zeff)/rdrag = 19.5 ± 1.0. this measurement is consistent with a flat λcdm model with planck parameters. | the completed sdss-iv extended baryon oscillation spectroscopic survey: measurement of the bao and growth rate of structure of the emission line galaxy sample from the anisotropic power spectrum between redshift 0.6 and 1.1 |
we measure the clustering of quasars of the final data release (dr16) of eboss. the sample contains $343\, 708$ quasars between redshifts 0.8 ≤ z ≤ 2.2 over $4699\, \mathrm{deg}^2$. we calculate the legendre multipoles (0,2,4) of the anisotropic power spectrum and perform a bao and a full-shape (fs) analysis at the effective redshift zeff = 1.480. the errors include systematic errors that amount to 1/3 of the statistical error. the systematic errors comprise a modelling part studied using a blind n-body mock challenge and observational effects studied with approximate mocks to account for various types of redshift smearing and fibre collisions. for the bao analysis, we measure the transverse comoving distance dm(zeff)/rdrag = 30.60 ± 0.90 and the hubble distance dh(zeff)/rdrag = 13.34 ± 0.60. this agrees with the configuration space analysis, and the consensus yields: dm(zeff)/rdrag = 30.69 ± 0.80 and dh(zeff)/rdrag = 13.26 ± 0.55. in the fs analysis, we fit the power spectrum using a model based on regularised perturbation theory, which includes redshift space distortions and the alcock-paczynski effect. the results are dm(zeff)/rdrag = 30.68 ± 0.90 and dh(zeff)/rdrag = 13.52 ± 0.51 and we constrain the linear growth rate of structure f(zeff)σ8(zeff) = 0.476 ± 0.047. our results agree with the configuration space analysis. the consensus analysis of the eboss quasar sample yields: dm(zeff)/rdrag = 30.21 ± 0.79, dh(zeff)/rdrag = 3.23 ± 0.47, and f(zeff)σ8(zeff) = 0.462 ± 0.045 and is consistent with a flat λcdm cosmological model using planck results. | the completed sdss-iv extended baryon oscillation spectroscopic survey: bao and rsd measurements from the anisotropic power spectrum of the quasar sample between redshift 0.8 and 2.2 |
we construct an updated and extended compilation of growth-rate data based on recent redshift-space distortion measurements. the data set consists of 34 data points and includes corrections for model dependence. in order to minimize overlap and maximize the independence of the data points, we also construct a subsample of this compilation (a "gold" growth data set) which consists of 18 data points. we test the consistency of this data set with the best-fit planck 15 /λ cdm parameters in the context of general relativity using the evolution equation for the growth factor δ (a ) with a w cdm background. we find tension at the ∼3 σ level between the best-fit parameters w (the dark energy equation of state), ω0 m (the matter density parameter), and σ8 (the matter power spectrum normalization on scales 8 h-1 mpc ) and the corresponding planck 15 /λ cdm parameters (w =-1 , ω0 m=0.315 , and σ8=0.831 ). we show that the tension disappears if we allow for evolution of the effective newton constant, parametrized as geff(a )/gn=1 +ga(1 -a )n-ga(1 -a )2n with n ≥2 where ga and n are parameters of the model, a is the scale factor, and z =1 /a -1 is the redshift. this parametrization satisfies three important criteria: a) positive energy of the graviton (geff>0 ), b) consistency with big bang nucleosynthesis constraints (geff(a ≪1 )/gn=1 ), and c) consistency with solar system tests (geff(a =1 )/gn=1 and geff'(a =1 )/gn=0 ). we show that the best-fit form of geff(z ) obtained from the growth data corresponds to weakening gravity at recent redshifts (decreasing function of z ), and we demonstrate that this behavior is not consistent with any scalar-tensor lagrangian with a real scalar field. finally, we use mgcamb to find the best-fit geff(z ) obtained from the planck cosmic microwave background power spectrum on large angular scales and show that it is a mildly increasing function of z , in 3 σ tension with the corresponding decreasing best-fit geff(z ) obtained from the growth data. | tension and constraints on modified gravity parametrizations of geff(z ) from growth rate and planck data |
we present a comprehensive catalog and analysis of broadband afterglow observations for 103 short-duration gamma-ray bursts (grbs), comprised of all short grbs from 2004 november to 2015 march with prompt follow-up observations in the x-ray, optical, near-infrared (nir), and/or radio bands. these afterglow observations have uncovered 71 x-ray detections, 30 optical/nir detections, and 4 radio detections. employing the standard afterglow synchrotron model, we perform joint probability analyses for a subset of 38 short grbs with well-sampled light curves to infer the burst isotropic-equivalent energies and circumburst densities. for this subset, we find median isotropic-equivalent γ-ray and kinetic energies of eγ,iso ≈ 2 × 1051 erg, and ek,iso ≈ (1-3) × 1051 erg, respectively, depending on the values of the model input parameters. we further find that short grbs occur in low-density environments, with a median density of n ≈ (3-15) × 10-3 cm-3, and that ≈80%-95% of bursts have densities of n ≲ 1 cm-3. we investigate trends between the circumburst densities and host galaxy properties, and find that events located at large projected offsets of ≳10 effective radii from their hosts exhibit particularly low densities of n ≲ 10-4 cm-3, consistent with an intergalactic medium-like environment. using late-time afterglow data for 11 events, we find a median jet opening angle of θj = 16 ± 10°. we also calculate a median beaming factor of fb ≈ 0.04, leading to a beaming-corrected total energy release of etrue ≈ 1.6 × 1050 erg. furthermore, we calculate a beaming-corrected event rate of {{r}}{{true}}={270}-180+1580 gpc-3 yr-1, or ≈ {8}-5+47 yr-1 within a 200 mpc volume, the advanced ligo/virgo typical detection distance for ns-ns binaries. | a decade of short-duration gamma-ray burst broadband afterglows: energetics, circumburst densities, and jet opening angles |
polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are thought to be widespread throughout the universe, because these classes of molecules are probably responsible for the unidentified infrared bands, a set of emission features seen in numerous galactic and extragalactic sources. despite their expected ubiquity, astronomical identification of specific aromatic molecules has proven elusive. we present the discovery of benzonitrile (c-c6h5cn), one of the simplest nitrogen-bearing aromatic molecules, in the interstellar medium. we observed hyperfine-resolved transitions of benzonitrile in emission from the molecular cloud tmc-1. simple aromatic molecules such as benzonitrile may be precursors for polycyclic aromatic hydrocarbon formation, providing a chemical link to the carriers of the unidentified infrared bands. | detection of the aromatic molecule benzonitrile (c-c6h5cn) in the interstellar medium |
we present in this work a new calculation of the standard-model benchmark value for the effective number of neutrinos, $n_{\rm eff}^{\rm sm}$, that quantifies the cosmological neutrino-to-photon energy densities. the calculation takes into account neutrino flavour oscillations, finite-temperature effects in the quantum electrodynamics plasma to ${\cal o}(e^3)$, where $e$ is the elementary electric charge, and a full evaluation of the neutrino--neutrino collision integral. we provide furthermore a detailed assessment of the uncertainties in the benchmark $n_{\rm eff}^{\rm sm}$ value, through testing the value's dependence on (i)~optional approximate modelling of the weak collision integrals, (ii)~measurement errors in the physical parameters of the weak sector, and (iii)~numerical convergence, particularly in relation to momentum discretisation. our new, recommended standard-model benchmark is $n_{\rm eff}^{\rm sm} = 3.0440 \pm 0.0002$, where the nominal uncertainty is attributed predominantly to errors incurred in the numerical solution procedure ($|\delta n_{\rm eff}| \sim10^{-4}$), augmented by measurement errors in the solar mixing angle $\sin^2\theta_{12}$ ($|\delta n_{\rm eff}| \sim10^{-4}$). | towards a precision calculation of the effective number of neutrinos n_eff in the standard model. part ii. neutrino decoupling in the presence of flavour oscillations and finite-temperature qed |
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