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the detection of gravitational waves from binary black-hole mergers by the ligo-virgo collaboration marks the dawn of an era when general-relativistic dynamics in its most extreme manifestation is directly accessible to observation. in the future, planned (space-based) observatories operating in the millihertz band will detect the intricate gravitational-wave signals from the inspiral of compact objects into massive black holes residing in galactic centers. such inspiral events are extremely effective probes of black-hole geometries, offering unparalleled precision tests of general relativity in its most extreme regime. this prospect has in the past two decades motivated a programme to obtain an accurate theoretical model of the strong-field radiative dynamics in a two-body system with a small mass ratio. the problem naturally lends itself to a perturbative treatment based on a systematic expansion of the field equations in the small mass ratio. at leading order one has a pointlike particle moving in a geodesic orbit around the large black hole. at subsequent orders, interaction of the particle with its own gravitational perturbation gives rise to an effective ‘self-force’, which drives the radiative evolution of the orbit, and whose effects can be accounted for order by order in the mass ratio. this review surveys the theory of gravitational self-force in curved spacetime and its application to the astrophysical inspiral problem. we first lay the relevant formal foundation, describing the rigorous derivation of the equation of self-forced motion using matched asymptotic expansions and other ideas. we then review the progress that has been achieved in numerically calculating the self-force and its physical effects in astrophysically realistic inspiral scenarios. we highlight the way in which, nowadays, self-force calculations make a fruitful contact with other approaches to the two-body problem and help inform an accurate universal model of binary black hole inspirals, valid across all mass ratios. we conclude with a summary of the state of the art, open problems and prospects. our review is aimed at non-specialist readers and is for the most part self-contained and non-technical; only elementary-level acquaintance with general relativity is assumed. where useful, we draw on analogies with familiar concepts from newtonian gravity or classical electrodynamics. | self-force and radiation reaction in general relativity |
we propose the generalized holographic dark energy model where the infrared cutoff is identified with the combination of the frw universe parameters: the hubble rate, particle and future horizons, cosmological constant, the universe lifetime (if finite) and their derivatives. it is demonstrated that with the corresponding choice of the cutoff one can map such holographic dark energy to modified gravity or gravity with a general fluid. explicitly, f( r) gravity and the general perfect fluid are worked out in detail and the corresponding infrared cutoff is found. using this correspondence, we get realistic inflation or viable dark energy or a unified inflationary-dark energy universe in terms of covariant holographic dark energy. | covariant generalized holographic dark energy and accelerating universe |
the international gamma-ray astrophysics laboratory (i n t e g r a l ) satellite has yielded unprecedented measurements of the soft gamma-ray spectrum of our galaxy. here we use those measurements to set constraints on dark matter (dm) that decays or annihilates into photons with energies e ≈0.02 - 2 mev . first, we revisit the constraints on particle dm that decays or annihilates to photon pairs. in particular, for decaying dm, we find that previous limits were overstated by roughly an order of magnitude. our new, conservative analysis finds that the dm lifetime must satisfy τ ≳5 ×1026 s ×(mχ/mev )-1 for dm masses mχ=0.054 - 3.6 mev . for mev-scale dm that annihilates into photons i n t e g r a l sets the strongest constraints to date. second, we target ultralight primordial black holes (pbhs) through their hawking radiation. this makes them appear as decaying dm with a photon spectrum peaking at e ≈5.77 /(8 π g mpbh), for a pbh of mass mpbh. we use the i n t e g r a l data to demonstrate that, at 95% c.l., pbhs with masses less than 1.2 ×1017 g cannot comprise all of the dm, setting the tightest bound to date on ultralight pbhs. | i n t e g r a l constraints on primordial black holes and particle dark matter |
"dark quark nuggets," a lump of dark quark matter, can be produced in the early universe for a wide range of confining gauge theories and serve as a macroscopic dark matter candidate. the two necessary conditions, a nonzero dark baryon number asymmetry and a first-order phase transition, can easily be satisfied for many asymmetric dark matter models and qcd-like gauge theories with a few massless flavors. for confinement scales from 10 kev to 100 tev, these dark quark nuggets with a huge dark baryon number have their masses vary from 1023 g to 10-7 g and their radii from 108 cm to 10-15 cm . such macroscopic dark matter candidates can be searched for by a broad scope of experiments and even new detection strategies. specifically, we have found that the gravitational microlensing experiments can probe heavier dark quark nuggets or smaller confinement scales around 10 kev; collision of dark quark nuggets can generate detectable and transient electromagnetic radiation signals; the stochastic gravitational wave signals from the first-order phase transition can be probed by the pulsar timing array observations and other space-based interferometry experiments; the approximately massless dark mesons can behave as dark radiation to be tested by the next-generation cosmic microwave background experiments; the free dark baryons, as a subcomponent of dark matter, can have direct detection signals for a sufficiently strong interaction strength with the visible sector. | dark quark nuggets |
we present the bacco project, a simulation framework specially designed to provide highly-accurate predictions for the distribution of mass, galaxies, and gas as a function of cosmological parameters. in this paper, we describe our main suite of gravity-only simulations ($l\sim 2\,$ gpc and 43203 particles) and present various validation tests. using a cosmology-rescaling technique, we predict the non-linear mass power spectrum over the redshift range 0 < z < 1.5 and over scales $10^{-2} \lt k/(\, h\, {\rm mpc}^{-1}) \lt 5$ for 800 points in an eight-dimensional cosmological parameter space. for an efficient interpolation of the results, we build an emulator and compare its predictions against several widely-used methods. over the whole range of scales considered, we expect our predictions to be accurate at the $2{{\ \rm per\ cent}}$ level for parameters in the minimal lambda cold dark matter model and to $3{{\ \rm per\ cent}}$ when extended to dynamical dark energy and massive neutrinos. we make our emulator publicly available under http://www.dipc.org/bacco | the bacco simulation project: exploiting the full power of large-scale structure for cosmology |
we formulate barrow holographic dark energy, by applying the usual holographic principle at a cosmological framework, but using the barrow entropy instead of the standard bekenstein-hawking one. the former is an extended black-hole entropy that arises due to quantum-gravitational effects which deform the black-hole surface by giving it an intricate, fractal form. we extract a simple differential equation for the evolution of the dark-energy density parameter, which possesses standard holographic dark energy as a limiting subcase, and we show that the scenario can describe the thermal history of the universe, with the sequence of matter and dark-energy eras. additionally, the new barrow exponent δ significantly affects the dark-energy equation of state, and according to its value it can lead it to lie in the quintessence regime, in the phantom regime, or experience the phantom-divide crossing during the evolution. | barrow holographic dark energy |
we have recently proposed a new class of gravitational scalar-tensor theories free from ostrogradski instabilities, in ref. [1]. as they generalize horndeski theories, or "generalized" galileons, we call them g3. these theories possess a simple formulation when the time hypersurfaces are chosen to coincide with the uniform scalar field hypersurfaces. we confirm that they contain only three propagating degrees of freedom by presenting the details of the hamiltonian formulation. we examine the coupling between these theories and matter. moreover, we investigate how they transform under a disformal redefinition of the metric. remarkably, these theories are preserved by disformal transformations that depend on the scalar field gradient, which also allow to map subfamilies of g3 into horndeski theories. | exploring gravitational theories beyond horndeski |
we analyse a simple extension of the sm with just an additional scalar singlet coupled to the higgs boson. we discuss the possible probes for electroweak baryogenesis in this model including collider searches, gravitational wave and direct dark matter detection signals. we show that a large portion of the model parameter space exists where the observation of gravitational waves would allow detection while the indirect collider searches would not. | gravitational wave, collider and dark matter signals from a scalar singlet electroweak baryogenesis |
we show that simplified models used to describe the interactions of dark matter with standard model particles do not in general respect gauge invariance and that perturbative unitarity may be violated in large regions of the parameter space. the modifications necessary to cure these inconsistencies may imply a much richer phenomenology and lead to stringent constraints on the model. we illustrate these observations by considering the simplified model of a fermionic dark matter particle and a vector mediator. imposing gauge invariance then leads to strong constraints from dilepton resonance searches and electroweak precision tests. furthermore, the new states required to restore perturbative unitarity can mix with standard model states and mediate interactions between the dark and the visible sector, leading to new experimental signatures such as invisible higgs decays. the resulting constraints are typically stronger than the `classic' constraints on dm simplified models such as monojet searches and make it difficult to avoid thermal overproduction of dark matter. | implications of unitarity and gauge invariance for simplified dark matter models |
the catwise2020 catalog consists of 1,890,715,640 sources over the entire sky selected from wide-field infrared survey explorer (wise) and neowise survey data at 3.4 and 4.6 μm (w1 and w2) collected from 2010 january 7 to 2018 december 13. this data set adds two years to that used for the catwise preliminary catalog, bringing the total to six times as many exposures spanning over 16 times as large a time baseline as the allwise catalog. the other major change from the catwise preliminary catalog is that the detection list for the catwise2020 catalog was generated using crowdsource from schlafly et al., while the catwise preliminary catalog used the detection software used for allwise. these two factors result in roughly twice as many sources in the catwise2020 catalog. the scatter with respect to spitzer photometry at faint magnitudes in the cosmos field, which is out of the galactic plane and at low ecliptic latitude (corresponding to lower wise coverage depth) is similar to that for the catwise preliminary catalog. the 90% completeness depth for the catwise2020 catalog is at w1 = 17.7 mag and w2 = 17.5 mag, 1.7 mag deeper than in the catwise preliminary catalog. in comparison to gaia, catwise2020 motions are accurate at the 20 mas yr-1 level for w1∼15 mag sources and at the ∼100 mas yr-1 level for w1∼17 mag sources. this level of accuracy represents a 12× improvement over allwise. the catwise catalogs are available in the wise/neowise enhanced and contributed products area of the nasa/ipac infrared science archive. | the catwise2020 catalog |
we search for a first-order phase transition gravitational wave signal in 45 pulsars from the nanograv 12.5-year dataset. we find that the data can be modeled in terms of a strong first order phase transition taking place at temperatures below the electroweak scale. however, we do not observe any strong preference for a phase-transition interpretation of the signal over the standard astrophysical interpretation in terms of supermassive black hole mergers; but we expect to gain additional discriminating power with future datasets, improving the signal to noise ratio and extending the sensitivity window to lower frequencies. an interesting open question is how well gravitational wave observatories could separate such signals. | searching for gravitational waves from cosmological phase transitions with the nanograv 12.5-year dataset |
aims: the nanohertz gravitational wave background (gwb) is expected to be an aggregate signal of an ensemble of gravitational waves emitted predominantly by a large population of coalescing supermassive black hole binaries in the centres of merging galaxies. pulsar timing arrays (ptas), which are ensembles of extremely stable pulsars at approximately kiloparsec distances precisely monitored for decades, are the most precise experiments capable of detecting this background. however, the subtle imprints that the gwb induces on pulsar timing data are obscured by many sources of noise that occur on various timescales. these must be carefully modelled and mitigated to increase the sensitivity to the background signal.methods: in this paper, we present a novel technique to estimate the optimal number of frequency coefficients for modelling achromatic and chromatic noise, while selecting the preferred set of noise models to use for each pulsar. we also incorporated a new model to fit for scattering variations in the bayesian pulsar timing package temponest. these customised noise models enable a more robust characterisation of single-pulsar noise. we developed a software package based on tempo2 to create realistic simulations of european pulsar timing array (epta) datasets that allowed us to test the efficacy of our noise modelling algorithms.results: using these techniques, we present an in-depth analysis of the noise properties of 25 millisecond pulsars (msps) that form the second data release (dr2) of the epta and investigate the effect of incorporating low-frequency data from the indian pulsar timing array collaboration for a common sample of ten msps. we used two packages, enterprise and temponest, to estimate our noise models and compare them with those reported using epta dr1. we find that, while in some pulsars we can successfully disentangle chromatic from achromatic noise owing to the wider frequency coverage in dr2, in others the noise models evolve in a much more complicated way. we also find evidence of long-term scattering variations in psr j1600-3053. through our simulations, we identify intrinsic biases in our current noise analysis techniques and discuss their effect on gwb searches. the analysis and results discussed in this article directly help to improve the sensitivity to the gwb signal and they are already being used as part of global pta efforts. | the second data release from the european pulsar timing array. ii. customised pulsar noise models for spatially correlated gravitational waves |
recently, it has been claimed that inflationary models with an inflection point in the scalar potential can produce a large resonance in the power spectrum of curvature perturbation. in this paper however we show that the previous analyses are incorrect. the reason is twofold: firstly, the inflaton is over-shot from a stage of standard inflation and so deviates from the slow-roll attractor before reaching the inflection. secondly, on the (or close to) the inflection point, the ultra-slow-roll trajectory supersede the slow-roll one and thus, the slow-roll approximations used in the literature cannot be used. we then reconsider the model and provide a recipe for how to produce nevertheless a large peak in the matter power spectrum via fine-tuning of parameters. | on primordial black holes from an inflection point |
we use gaia data release 2 to determine the mean proper motions for 150 milky way globular clusters (almost the entire known population), with a typical uncertainty of 0.05 mas yr-1 limited mainly by systematic errors. combining them with distance and line-of-sight velocity measurements from the literature, we analyse the distribution of globular clusters in the 6d phase space, using both position/velocity and action/angle coordinates. the population of clusters in the central 10 kpc has a mean rotational velocity reaching 50-80 km s-1 , and a nearly isotropic velocity dispersion 100-120 km s-1 , while in the outer galaxy, the cluster orbits are strongly radially anisotropic. we confirm a concentration of clusters at high radial action in the outer region of the galaxy. finally, we explore a range of equilibrium distribution function-based models for the entire globular cluster system, and the information they provide about the potential of the milky way. the dynamics of clusters is best described by models with the circular velocity between 10 and 50 kpc staying in the range 210-240 km s-1. | proper motions and dynamics of the milky way globular cluster system from gaia dr2 |
we study an axion-like particle (alp) that experiences a first-order phase transition with respect to its mass or potential minimum. this can be realized if the alp obtains a potential from non-perturbative effects of su(n) gauge theory that is confined via the first-order phase transition. similar dynamics are achieved in the so-called trapped misalignment mechanism, where the alp is trapped in a false vacuum at high temperatures until it begins to oscillate about the true minimum. the resulting alp abundance is significantly enhanced compared to the standard misalignment mechanism, explaining dark matter in a broader parameter space that is accessible to experiments e.g. iaxo, alps-ii, and dm-radio. furthermore, the viable parameter space includes a region of the mass ma ≃10-8 -10-7 ev and the alp-photon coupling gaγγ ≃10-11gev-1 that can explain the recent observation of very high energy photons from grb221009a via axion-photon oscillations. the parameter region suggests that the fopt can generate gravitational waves that explain the nanograv hint. if the alp in this region explains dark matter, then the alp might have experienced a first-order phase transition. finally we also discuss cosmological aspects of the dark sector that triggers the fopt and propose a possible solution to the cooling problem of dark glueballs. | axion dark matter from first-order phase transition, and very high energy photons from grb 221009a |
we present an updated analysis of the first-order phase transition associated with symmetry breaking in the early universe in a classically scale-invariant model extended with a new su(2) gauge group. including recent developments in understanding supercooled phase transitions, we compute all of its characteristics and significantly constrain the parameter space. we then predict gravitational wave spectra generated during this phase transition and by computing the signal-to-noise ratio we conclude that this model is well-testable (and falsifiable) with lisa. we also provide predictions for the relic dark matter abundance. it is consistent with observations in a rather narrow part of the parameter space. we strongly constrain the so-called supercool dark matter scenario based on an improved description of percolation and reheating after the phase transition as well as the inclusion of the running of couplings. finally, we devote attention to the renormalisation-scale dependence of the results. even though our main results are obtained with the use of renormalisation-group improved effective potential, we also perform a fixed-scale analysis which proves that the dependence on the scale is not only qualitative but also quantitative. | conformal model for gravitational waves and dark matter: a status update |
we present a catalog of hard x-ray sources detected in the first 105 months of observations with the burst alert telescope (bat) coded-mask imager on board the swift observatory. the 105-month swift-bat survey is a uniform hard x-ray all-sky survey with a sensitivity of 8.40× {10}-12 {erg} {{{s}}}-1 {cm}}-2 over 90% of the sky and 7.24× {10}-12 {erg} {{{s}}}-1 {cm}}-2 over 50% of the sky in the 14-195 kev band. the swift-bat 105-month catalog provides 1632 (422 new detections) hard x-ray sources in the 14-195 kev band above the 4.8σ significance level. adding to the previously known hard x-ray sources, 34% (144/422) of the new detections are identified as seyfert active galactic nuclei (agns) in nearby galaxies (z< 0.2). the majority of the remaining identified sources are x-ray binaries (7%, 31) and blazars/bl lac objects (10%, 43). as part of this new edition of the swift-bat catalog, we release eight-channel spectra and monthly sampled light curves for each object in the online journal and at the swift-bat 105-month website. | the 105-month swift-bat all-sky hard x-ray survey |
adopting a binned method, we model-independently reconstruct the mass function of primordial black holes (pbhs) from gwtc-3 and find that such a pbh mass function can be explained by a broad red-tilted power spectrum of curvature perturbations if all the events (or the small effective spin events) have a primordial origin. even though gw190521 with component masses in upper mass gap (m > 65m⊙) can be naturally interpreted in the pbh scenario, the events (including gw190814, gw190425, gw200105, and gw200115) with component masses in the light mass range (m < 3m⊙) are quite unlikely to be explained by binary pbhs although there are no electromagnetic counterparts because the corresponding pbh merger rates are much smaller than those given by ligo-virgo. furthermore, we predict that both the gravitational-wave (gw) background generated by the binary pbhs and the scalar-induced gws accompanying the formation of pbhs should be detected by the ground-based and space-borne gw detectors and pulsar timing arrays in the future. | confronting the primordial black hole scenario with the gravitational-wave events detected by ligo-virgo |
we present a measurement of the baryon acoustic oscillation (bao) scale at redshift z = 2.35 from the three-dimensional correlation of lyman-α (lyα) forest absorption and quasars. the study uses 266 590 quasars in the redshift range 1.77 < z < 3.5 from the sloan digital sky survey (sdss) data release 14 (dr14). the sample includes the first two years of observations by the sdss-iv extended baryon oscillation spectroscopic survey (eboss), providing new quasars and re-observations of boss quasars for improved statistical precision. statistics are further improved by including lyα absorption occurring in the lyβ wavelength band of the spectra. from the measured bao peak position along and across the line of sight, we determined the hubble distance dh and the comoving angular diameter distance dm relative to the sound horizon at the drag epoch rd: dh(z = 2.35)/rd = 9.20 ± 0.36 and dm(z = 2.35)/rd = 36.3 ± 1.8. these results are consistent at 1.5σ with the prediction of the best-fit spatially-flat cosmological model with the cosmological constant reported for the planck (2016) analysis of cosmic microwave background anisotropies. combined with the lyα auto-correlation measurement presented in a companion paper, the bao measurements at z = 2.34 are within 1.7σ of the predictions of this model. | baryon acoustic oscillations from the cross-correlation of lyα absorption and quasars in eboss dr14 |
gravity theories that modify general relativity in the slow-motion regime can introduce nonperturbative corrections to the stochastic gravitational-wave background~(sgwb) from supermassive black-hole binaries in the nano-hertz band, while remaining perturbative in the highly-relativistic regime and satisfying current post-newtonian~(pn) constraints. we present a model-agnostic formalism to map such theories into a modified tilt for the sgwb spectrum, showing that negative pn corrections (in particular -2pn) can alleviate the tension in the recent pulsar-timing-array data if the detected sgwb is interpreted as arising from supermassive binaries. despite being preliminary, current data have already strong constraining power, for example they set a novel (conservative) upper bound on theories with time-varying newton's constant at least at the level of $\dot{g}/g \lesssim 10^{-5} \text{yr}^{-1}$ for redshift $z=[0.1\div1]$. we also show that nanograv data are best fitted by a broken power-law interpolating between a dominant -2pn or -3pn modification at low frequency, and the standard general-relativity scaling at high frequency. nonetheless, a modified gravity explanation should be confronted with binary eccentricity, environmental effects, nonastrophysical origins of the signal, and scrutinized against statistical uncertainties. these novel tests of gravity will soon become more stringent when combining all pulsar-timing-array facilities and when collecting more data. | novel tests of gravity using nano-hertz stochastic gravitational-wave background signals |
we live in a time of extraordinary discovery and progress in astronomy and astrophysics. the next decade will transform our understanding of the universe and humanity's place in it. every decade the u.s. agencies that provide primary federal funding for astronomy and astrophysics request a survey to assess the status of, and opportunities for the nation's efforts to forward our understanding of the cosmos. pathways to discovery in astronomy and astrophysics for the 2020s identifies the most compelling science goals and presents an ambitious program of ground- and space-based activities for future investment in the next decade and beyond. the decadal survey identifies three important science themes for the next decade aimed at investigating earth-like extrasolar planets, the most energetic processes in the universe, and the evolution of galaxies. the astro2020 report also recommends critical near-term actions to support the foundations of the profession as well as the technologies and tools needed to carry out the science. | pathways to discovery in astronomy and astrophysics for the 2020s |
some time ago we have suggested that positive vacuum energy exhibits a finite quantum break time, which can be a signal that a positive cosmological constant is inconsistent. from the requirement that universe never undergoes through quantum breaking, we have derived an absolute lower bound on the speed of variation of positive vacuum energy. the same suggestion about exclusion of positive cosmological constant was made recently. we show that the new bound represents a particular string theoretic version of the old bound, which is more general. in this light, we show that the existing window still provides a large room for the inflationary and dark energy model building. in particular, the inflationary models with gravitational strength interactions, are protected against fast quantum breaking. | on exclusion of positive cosmological constant |
we report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 tev and 1 pev in the galactic disk. particularly, all gamma rays above 398 tev are observed apart from known tev gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of π0's produced through the interaction of protons with the interstellar medium in the galaxy. this is strong evidence that cosmic rays are accelerated beyond pev energies in our galaxy and spread over the galactic disk. | first detection of sub-pev diffuse gamma rays from the galactic disk: evidence for ubiquitous galactic cosmic rays beyond pev energies |
the baryon oscillation spectroscopic survey (boss), part of the sloan digital sky survey (sdss) iii project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. we document here the target selection algorithms used to create the galaxy samples that comprise boss. we also present the algorithms used to create large-scale structure catalogues for the final data release (dr12) samples and the associated random catalogues that quantify the survey mask. the algorithms are an evolution of those used by the boss team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. the code used, designated mksample, is released with this paper. | sdss-iii baryon oscillation spectroscopic survey data release 12: galaxy target selection and large-scale structure catalogues |
we propose a mechanism that forms primordial black holes (pbhs) via a first-order electroweak phase transition (foewpt). the foewpt is realized by extending the standard model with a real singlet scalar, while the pbh formation is achieved by the collapse of nontopological solitons called fermi-balls. such solitons form via trapping fermions in the false vacuum during the foewpt, and they eventually collapse into pbhs due to the internal yukawa attractive force. we demonstrate that a scenario with pbh dark matter candidate can exist, and the typical experimental signals include foewpt gravitational waves and the multilepton/jet or displaced vertex final states at the lhc. | primordial black holes from an electroweak phase transition |
a proper understanding of the milky way (mw) dwarf galaxies in a cosmological context requires knowledge of their 3d velocities and orbits. however, proper motion (pm) measurements have generally been of limited accuracy and are available only for more massive dwarfs. we therefore present a new study of the kinematics of the mw dwarf galaxies. we use the gaia dr2 for those dwarfs that have been spectroscopically observed in the literature. we derive systemic pms for 39 galaxies and galaxy candidates out to 420 kpc, and generally find good consistency for the subset with measurements available from other studies. we derive the implied galactocentric velocities, and calculate orbits in canonical mw halo potentials of low (0.8 × 1012 m⊙) and high mass (1.6 × 1012 m⊙). comparison of the distributions of orbital apocenters and 3d velocities to the halo virial radius and escape velocity, respectively, suggests that the satellite kinematics are best explained in the high-mass halo. tuc iii, crater ii, and additional candidates have orbital pericenters small enough to imply significant tidal influences. relevant to the missing satellite problem, the fact that fewer galaxies are observed to be near apocenter than near pericenter implies that there must be a population of distant dwarf galaxies yet to be discovered. of the 39 dwarfs: 12 have orbital poles that do not align with the mw plane of satellites (given reasonable assumptions about its intrinsic thickness); 10 have insufficient pm accuracy to establish whether they align; and 17 satellites align, of which 11 are co-orbiting and (somewhat surprisingly, in view of prior knowledge) 6 are counter-orbiting. group infall might have contributed to this, but no definitive association is found for the members of the crater-leo group. | gaia dr2 proper motions of dwarf galaxies within 420 kpc. orbits, milky way mass, tidal influences, planar alignments, and group infall |
in recent years, gravity has enjoyed considerable attention in the literature and important results have been obtained. however, the question of how many physical degrees of freedom the theory propagates—and how this number may depend on the form of the function f—has not been answered satisfactorily. in this article it is shown that a hamiltonian analysis based on the dirac‑bergmann algorithm—one of the standard methods to address this type of question—fails. the source of the failure is isolated and it is shown that other commonly considered teleparallel theories of gravity are affected by the same problem. furthermore, it is pointed out that the number of degrees of freedom obtained in phys. rev. d 106 no. 4, (2022) by k. hu, t. katsuragawa, and t. qui (namely eight), based on the dirac‑bergmann algorithm, is wrong. using a different approach, it is shown that the upper bound on the degrees of freedom is seven. finally, a more promising strategy for settling this important question is proposed. | hamiltonian analysis of f(q)f(\\mathbb {q}) gravity and the failure of the dirac–bergmann algorithm for teleparallel theories of gravity |
pulsar timing array collaborations have recently announced the discovery of a stochastic gravitational wave (gw) background at nanohertz frequencies. we analyze the gw signals from the domination of ultralow mass primordial black holes (pbhs) in the early universe and show that they can explain this recent discovery. this scenario requires a relatively broad peak in the power spectrum of scalar perturbations from inflation with a spectral index in a narrow range of 1.45-1.6. the resulting pbh population would have mass around 108 g , and the initial abundance βf lies between 10-10 and 10-9. we find that this explanation is preferred by the data over the generic model, assuming supermassive black holes as the source. these very light pbhs would decay before big bang nucleosynthesis; however, upcoming third-generation terrestrial laser interferometers would be able to test the model by observing the gw spectrum produced during the formation of the pbhs. also, the scalar power spectra associated with our scenario will be within the reach of pixie probing cosmic microwave background spectral distortions. | ultralow mass primordial black holes in the early universe can explain the pulsar timing array signal |
we present a combined tomographic weak gravitational lensing analysis of the kilo degree survey (kv450) and the dark energy survey (des-y1). we homogenize the analysis of these two public cosmic shear datasets by adopting consistent priors and modeling of nonlinear scales, and determine new redshift distributions for des-y1 based on deep public spectroscopic surveys. adopting these revised redshifts results in a 0.8σ reduction in the des-inferred value for s8, which decreases to a 0.5σ reduction when including a systematic redshift calibration error model from mock des data based on the mice2 simulation. the combined kv450+des-y1 constraint on s8 = 0.762-0.024+0.025 is in tension with the planck 2018 constraint from the cosmic microwave background at the level of 2.5σ. this result highlights the importance of developing methods to provide accurate redshift calibration for current and future weak-lensing surveys. | kids+viking-450 and des-y1 combined: cosmology with cosmic shear |
cosmological observations indicate that most of the matter in the universe is dark matter. dark matter in the form of weakly interacting massive particles (wimps) can be detected directly, via its elastic scattering off target nuclei. most current direct detection experiments only measure the energy of the recoiling nuclei. however, directional detection experiments are sensitive to the direction of the nuclear recoil as well. due to the sun's motion with respect to the galactic rest frame, the directional recoil rate has a dipole feature, peaking around the direction of the solar motion. this provides a powerful tool for demonstrating the galactic origin of nuclear recoils and hence unambiguously detecting dark matter. furthermore, the directional recoil distribution depends on the wimp mass, scattering cross section and local velocity distribution. therefore, with a large number of recoil events it will be possible to study the physics of dark matter in terms of particle and astrophysical properties. we review the potential of directional detectors for detecting and characterizing wimps. | a review of the discovery reach of directional dark matter detection |
we propose an alternative refined de sitter conjecture. it is given by a natural condition on a combination of the first and second derivatives of the scalar potential. we derive our conjecture in the same weak coupling, semi-classical regime where the previous refined de sitter conjecture was derived, using the same tools together with a few more assumptions that we discuss. we further test and constrain free parameters in our conjecture using data points of a classical type iia supergravity setup. interestingly, our conjecture easily accommodates slow-roll single field inflation with a concave potential, favored by observations. the standard quintessence potential is in tension with our new conjecture, and we thus propose a different type of quintessence model. | further refining the de sitter swampland conjecture |
we present a blind time-delay cosmographic analysis for the lens system des j0408-5354. this system is extraordinary for the presence of two sets of multiple images at different redshifts, which provide the opportunity to obtain more information at the cost of increased modelling complexity with respect to previously analysed systems. we perform detailed modelling of the mass distribution for this lens system using three band hubble space telescope imaging. we combine the measured time delays, line-of-sight central velocity dispersion of the deflector, and statistically constrained external convergence with our lens models to estimate two cosmological distances. we measure the 'effective' time-delay distance corresponding to the redshifts of the deflector and the lensed quasar $d_{\delta t}^{\rm eff}=$ $3382_{-115}^{+146}$ mpc and the angular diameter distance to the deflector dd = $1711_{-280}^{+376}$ mpc, with covariance between the two distances. from these constraints on the cosmological distances, we infer the hubble constant h0= $74.2_{-3.0}^{+2.7}$ km s-1 mpc-1 assuming a flat λcdm cosmology and a uniform prior for ωm as $\omega _{\rm m} \sim \mathcal {u}(0.05, 0.5)$ . this measurement gives the most precise constraint on h0 to date from a single lens. our measurement is consistent with that obtained from the previous sample of six lenses analysed by the h0 lenses in cosmograil's wellspring (h0licow) collaboration. it is also consistent with measurements of h0 based on the local distance ladder, reinforcing the tension with the inference from early universe probes, for example, with 2.2σ discrepancy from the cosmic microwave background measurement. | strides: a 3.9 per cent measurement of the hubble constant from the strong lens system des j0408-5354 |
black hole superradiance is a powerful probe of light, weakly coupled hidden sector particles. many candidate particles, such as axions, generically have self-interactions that can influence the evolution of the superradiant instability. as pointed out in [a. gruzinov, arxiv:1604.06422.] in the context of a toy model, much of the existing literature on spin-0 superradiance does not take into account the most important self-interaction-induced processes. these processes lead to energy exchange between quasi-bound levels and particle emission to infinity; for large self-couplings, superradiant growth is saturated at a quasi-equilibrium configuration of reduced level occupation numbers. in this paper, we perform a detailed analysis of the rich dynamics of spin-0 superradiance with self-interactions, and the resulting observational signatures. we focus on quartic self-interactions, which dominate the evolution for most models of interest. we explore multiple distinct regimes of parameter space introduced by a nonzero self-interaction, including the simultaneous population of two or more bound levels; at large coupling, we confirm the basic picture of quasiequilibrium saturation and provide evidence that the "bosenova" collapse does not occur in most of the astrophysical parameter space. compared to gravitational superradiance, we find that gravitational wave "annihilation" signals and black hole spin-down are parametrically suppressed with increasing interactions, while new gravitational wave "transition" signals can take place for moderate interactions. the novel phenomenon of scalar wave emission is less suppressed at large couplings, and if the particle has standard model interactions, then coherent, monochromatic axion wave signals from black hole superradiance may be detectable in proposed axion dark matter experiments. | black hole superradiance of self-interacting scalar fields |
in the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. we study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. in particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflation model and point out that the gravitational particle production is efficient even if dark matter mass is much larger than the hubble scale during inflation as long as it is smaller than the inflaton mass. | production of purely gravitational dark matter |
we apply the recently developed positivity bounds for particles with spin, applied away from the forward limit, to the low energy effective theories of massive spin-1 and spin-2 theories. for spin-1 theories, we consider the generic proca eft which arises at low energies from a heavy higgs mechanism, and the special case of a charged galileon for which the eft is reorganized by the galileon symmetry. for spin-2, we consider generic λ5 massive gravity theories and the special `ghost-free' λ3 theories. remarkably we find that at the level of 2-2 scattering, the positivity bounds applied to λ5 massive gravity theories, impose the special tunings which generate the λ3 structure. for λ3 massive gravity theories, the island of positivity derived in the forward limit appears relatively stable against further bounds. | positivity bounds for massive spin-1 and spin-2 fields |
the nature of dark matter is one of the most pressing questions in physics. yet all our present knowledge of the dark sector to date comes from its gravitational interactions with astrophysical systems. moreover, astronomical results still have immense potential to constrain the particle properties of dark matter in the near future. we introduce a simple 2d parameter space which classifies models in terms of a particle physics interaction strength and a characteristic astrophysical scale on which new physics appears, in order to facilitate communication between the fields of particle physics and astronomy. we survey the known astrophysical anomalies that are suggestive of non-trivial dark matter particle physics, and present a theoretical and observational program for future astrophysical measurements that will shed light on the nature of dark matter. | gravitational probes of dark matter physics |
we revisit the decoupling of neutrinos in the early universe with flavour oscillations. we rederive the quantum kinetic equations which determine the neutrino evolution based on a bbgky-like hierarchy, and include for the first time the full collision term, with both on- and off-diagonal terms for all relevant reactions. we focus on the case of zero chemical potential and solve these equations numerically. we also develop an approximate scheme based on the adiabatic evolution in the matter basis. in fact, the large difference between the oscillations and cosmological time scales allows to consider averaged flavour oscillations which can speed up the numerical integration by two orders of magnitude, when combined with a direct computation of the differential system jacobian. the approximate numerical scheme is also useful to gain more insight into the physics of neutrino decoupling. including the most recent results on plasma thermodynamics qed corrections, we update the effective number of neutrinos to neff = 3.0440. finally we study the impact of flavour oscillations during neutrino decoupling on the subsequent primordial nucleosynthesis. | neutrino decoupling including flavour oscillations and primordial nucleosynthesis |
we report the first experimental results on spin-dependent elastic weakly interacting massive particle (wimp) nucleon scattering from the xenon1t dark matter search experiment. the analysis uses the full ton year exposure of xenon1t to constrain the spin-dependent proton-only and neutron-only cases. no significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the wimp-nucleon interactions. this includes the most stringent constraint to date on the wimp-neutron cross section, with a minimum of 6.3 ×10-42 cm2 at 30 gev /c2 and 90% confidence level. the results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator. | constraining the spin-dependent wimp-nucleon cross sections with xenon1t |
these lectures provide an introduction to models and direct detection of dark matter. we summarize the general features and motivations for candidates in the full dark matter mass range, and then restrict to the kev-tev mass window. candidates in this window can be produced by thermal mechanisms in the standard cosmology, and are an important target for experimental searches. we then turn to sub-gev dark matter (light dark matter) and dark sectors, an area where many new models and experiments are currently being proposed. we discuss the cosmology of dark sectors, specific portal realizations, and some of the prospects for detection. the final parts of these lectures focus on the theory for direct detection, both reviewing the fundamentals for nuclear recoils of wimps and describing new directions for sub-gev candidates. a version of these lectures was originally presented at the tasi 2018 summer school on "theory in an era of data". | tasi lectures on dark matter models and direct detection |
primordial black holes can have substantial spin—a fundamental property that has a strong effect on its evaporation rate. we conduct a comprehensive study of the detectability of primordial black holes with non-negligible spin, via the searches for the neutrinos and positrons in the mev energy range. diffuse supernova neutrino background searches and observation of the 511 kev gamma-ray line from positrons in the galactic center set competitive constraints. spinning primordial black holes are probed up to a slightly higher mass range compared to nonspinning ones. our constraint using neutrinos is slightly weaker than that due to the diffuse gamma-ray background, but complementary and robust. our positron constraints are typically weaker in the lower mass range and stronger in the higher mass range for the spinning primordial black holes compared to the nonspinning ones. they are generally stronger than those derived from the diffuse gamma-ray measurements for primordial black holes having masses greater than a few ×1016 g . | neutrino and positron constraints on spinning primordial black hole dark matter |
we estimate the gravitational wave spectra generated in strongly supercooled phase transitions by bubble collisions and fluid motion. we derive analytically in the thin-wall approximation the efficiency factor that determines the share of the energy released in the transition between the scalar field and the fluid. we perform numerical simulations including the efficiency factor as a function of bubble radius separately for all points on the bubble surfaces to take into account their different collision times. we find that the efficiency factor does not significantly change the gravitational wave spectra and show that the result can be approximated by multiplying the spectrum obtained without the efficiency factor by its value at the radius reff≃5 /β , where β is the approximate inverse duration of the transition. we also provide updated fits for the gravitational wave spectra produced in strongly supercooled transitions from both bubble collisions and fluid motion depending on the behaviour of the sources after the collision. | gravitational waves from bubble collisions and fluid motion in strongly supercooled phase transitions |
many motivated extensions of the standard model predict the existence of cosmic strings. gravitational waves originating from the dynamics of the resulting cosmic string network have the ability to probe many otherwise inaccessible properties of the early universe. in this study we show how the spectrum of gravitational waves from a cosmic string network can be used to test the equation of state of the early universe prior to big bang nucleosynthesis (bbn). we also demonstrate that current and planned gravitational wave detectors such as ligo, lisa, decigo/bbo, and et/ce have the potential to detect signals of a non-standard pre-bbn equation of state and evolution of the early universe (e.g., early non-standard matter domination or kination domination) or new degrees of freedom active in the early universe beyond the sensitivity of terrestrial collider experiments and cosmic microwave background measurements. | probing the pre-bbn universe with gravitational waves from cosmic strings |
we suggest a novel experimental concept for detecting mev-to-gev-mass dark matter, in which the dark matter scatters off electrons in a scintillating target and produces a signal of one or a few photons. new large-area photodetectors are needed to measure the photon signal with negligible dark counts, which could be constructed from transition edge sensor (tes) or microwave kinetic inductance detector (mkid) technology. alternatively, detecting two photons in coincidence may allow the use of conventional photodetectors like photomultiplier tubes. we describe why scintillators may have distinct advantages over other experiments searching for a low ionization signal from sub-gev dark matter, as there are fewer potential sources of spurious backgrounds. we discuss various target choices, but focus on calculating the expected dark matter-electron scattering rates in three scintillating crystals: sodium iodide (nai), cesium iodide (csi), and gallium arsenide (gaas). among these, gaas has the lowest band gap (1.52 ev) compared to nai (5.9 ev) or csi (6.4 ev), which in principle allows it to probe dark matter masses as low as ∼0.5 mev , compared to ∼1.5 mev with nai or csi. we compare these scattering rates with those expected in silicon (si) and germanium (ge). the proposed experimental concept presents an important complementary path to existing efforts, and its potential advantages may make it the most sensitive direct-detection probe of dark matter down to mev masses. | direct detection of sub-gev dark matter with scintillating targets |
we study the distortions of equilibrium spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early universe. we solve the integro-differential kinetic equations for the neutrino density matrix, including three-flavor oscillations and finite temperature corrections from qed up to the next-to-leading order o(e3) for the first time. in addition, the equivalent kinetic equations in the mass basis of neutrinos are directly solved, and we numerically evaluate the distortions of the neutrino spectra in the mass basis as well, which can be easily extrapolated into those for non-relativistic neutrinos in the current universe. in both bases, we find the same value of the effective number of neutrinos, neff=3.044, which parameterizes the total neutrino energy density. the estimated error for the value of neff due to the numerical calculations and the choice of neutrino mixing parameters would be at most 0.0005. | a precision calculation of relic neutrino decoupling |
we present the survey design and initial results of the alma cycle 9 program of dualz, which aims to establish a joint alma and jwst public legacy field targeting the massive galaxy cluster abell 2744. dualz features a contiguous $4'\times6'$ alma 30-ghz-wide mosaic in band 6, covering areas of $\mu>2$ down to a sensitivity of $\sigma=32.7~\mu$jy. through a blind search, we identified 69 dust continuum sources at s/n $\gtrsim5.0$ with median redshift and intrinsic 1.2-mm flux of $z=2.30$ and $s_{\rm 1.2mm}^{\rm int}=0.24$~mjy. of these, 27 have been spectroscopically confirmed, leveraged by the latest nirspec observations, while photometric redshift estimates are constrained by the comprehensive hst, nircam, and alma data for the remaining sources. with priors, we further identify a [cii]158 $\mu$m line emitter at $z=6.3254\pm0.0004$, confirmed by the latest nirspec spectroscopy. the nircam counterparts of the 1.2-mm continuum exhibit undisturbed morphologies, denoted either by disk or spheroid, implying the triggers for the faint mm emission are less catastrophic than mergers. we have identified 8 hst-dark galaxies (f150w$>$27mag, f150w$-$f444w$>$2.3) and 2 jwst-dark (f444w$>$30mag) galaxy candidates among the alma continuum sources. the former includes face-on disk galaxies, hinting that substantial dust obscuration does not always result from inclination. we also detect a marginal dust emission from an x-ray-detected galaxy at $z_{\rm spec}=10.07$, suggesting an active co-evolution of the central black hole and its host. we assess the infrared luminosity function up to $z\sim10$ and find it consistent with predictions from galaxy formation models. to foster diverse scientific outcomes from the community, we publicly release reduced alma mosaic maps, cubes, and the source catalog. | dualz: deep uncover-alma legacy high-z survey |
it is well known that a primordial black hole (pbh) can be generated in the inflation process of the early universe, especially when the inflation field has a number of non-trivial features that could break the slow-roll condition. in this study, we investigate a toy model of inflation with bumpy potential, which has one or several bumps. we determined that the potential with multi-bump can generate power spectra with multi-peaks in small-scale region, which can in turn predict the generation of primordial black holes in various mass ranges. we also consider the two possibilities of pbh formation by spherical and elliptical collapses. finally, we discuss the scalar-induced gravitational waves (sigws) generated by linear scalar perturbations at second-order. *supported by the national natural science foundation of china (11653002, 11875141), partially the fundamental research funds for the central universities (innovation funded projects) (2020cxzz105) | on primordial black holes and secondary gravitational waves generated from inflation with solo/multi-bumpy potential |
we outline the unique opportunities and challenges in the search for "ultraheavy" dark matter candidates with masses between roughly 10 tev and the planck scale m_{\rm pl} ≈ 10^{16} tev. this mass range presents a wide and relatively unexplored dark matter parameter space, with a rich space of possible models and cosmic histories. we emphasize that both current detectors and new, targeted search techniques, via both direct and indirect detection, are poised to contribute to searches for ultraheavy particle dark matter in the coming decade. we highlight the need for new developments in this space, including new analyses of current and imminent direct and indirect experiments targeting ultraheavy dark matter and development of new, ultra-sensitive detector technologies like next-generation liquid noble detectors, neutrino experiments, and specialized quantum sensing techniques. | snowmass2021 cosmic frontier white paper: ultraheavy particle dark matter |
we examine the effects of a stiff pre-recombination era on the present day's energy spectrum of the primordial gravitational waves. if the background total equation of state parameter at the pre-recombination era is described by a kination era one, this directly affects the modes with characteristic wavenumbers which reenter the hubble horizon during this stiff era. the stiff era causes a broken-power-law effect on the energy spectrum of the gravitational waves. we use two approaches, one model agnostic and a specific model that can realize this scenario. in all cases, the inflationary era can be realized either by some theory leading to a standard red-tilted tensor spectral index or by some theory which has a mild tensor spectral index $n_{\mathcal{t}}=0.17-0.37$ like an einstein-gauss-bonnet theory. for the model agnostic scenario case, the nanograv signal can be explained by the stiff pre-recombination era combined with an inflationary era with a mild blue-tilted tensor spectral index $n_{\mathcal{t}}=0.37$ and a low-reheating temperature $t_r\sim 0.1$gev. in the same case, the red-tilted inflationary theory signal can be detectable by the future lisa, bbo and decigo experiments. the model dependent approach is based on a higgs-axion model which can yield multiple deformations of the background total equation of state parameter, causing multiple broken-power-law behaviors occurring in various eras before and after the recombination era. in this case, the nanograv signal is explained by this model in conjunction with an inflationary era with a really mild blue-tilted tensor spectral index $n_{\mathcal{t}}=0.17$ and a low-reheating temperature $t_r\sim 20\,$gev. in this case, the signal can be detectable by the future litebird experiment, which is a very characteristic pattern in the tail of the primordial gravitational wave energy spectrum. | a stiff pre-cmb era with a mildly blue-tilted tensor inflationary era can explain the 2023 nanograv signal |
singularities in any physical theory are either remarkable indicators of the unknown underlying fundamental theory, or indicate a change in the description of the physical reality. in general relativity there are three fundamental kinds of singularities that might occur, firstly the black hole spacelike crushing singularities, e.g. in the schwarzschild case and two cosmological spacelike singularities appearing in finite-time, namely, the big bang singularity and the big rip singularity. in the case of black hole and big bang singularity, the singularity indicates that the physics is no longer described by the classical gravity theory but some quantum version of gravity is probably needed. the big rip is a future singularity which appears in the context of general relativity due to a phantom scalar field needed to describe the dark energy era. apart from the big rip singularity, a variety of finite-time future singularities, such as, sudden singularity, big freeze singularity, generalized sudden singularity, w-singularity and so on, are allowed in various class of cosmological models irrespective of their origin. the occurrence of these finite-time singularities has been intensively investigated in the context of a variety of dark energy, modified gravity, and other alternative cosmological theories. these singularities suggest that the current cosmological scenario is probably an approximate version of a fundamental theory yet to be discovered. in this review we provide a concrete overview of the cosmological theories constructed in the context of einstein's general relativity and modified gravity theories that may lead to finite-time cosmological singularities. we also discuss various approaches suggested in the literature that could potentially prevent or mitigate finite-time singularities within the cosmological scenarios. | finite-time cosmological singularities and the possible fate of the universe |
ultra-light primordial black holes, with masses mpbh < 109g, evaporate before big-bang nucleosynthesis and can therefore not be directly constrained. they can however be so abundant that they dominate the universe content for a transient period (before reheating the universe via hawking evaporation). if this happens, they support large cosmological fluctuations at small scales, which in turn induce the production of gravitational waves through second-order effects. contrary to the primordial black holes, those gravitational waves survive after evaporation, and can therefore be used to constrain such scenarios. in this work, we show that for induced gravitational waves not to lead to a backreaction problem, the relative abundance of black holes at formation, denoted ωpbh,f, should be such that ωpbh,f < 10-4(mpbh/109g)-1/4. in particular, scenarios where primordial black holes dominate right upon their formation time are all excluded (given that mpbh > 10 g for inflation to proceed at ρ1/4 < 1016 gev). this sets the first constraints on ultra-light primordial black holes. | gravitational waves from a universe filled with primordial black holes |
we show that the recently reported cosmic gravitational wave background by the nanograv 15-year collaboration may be the result of resonant particle creation during inflation. for the appropriate amplitude and particle mass an enhancement of the primordial scalar power spectrum could induce secondary induced gravitational waves (sigw) which will appear on a scale corresponding to the frequency of the nanograv detection. since the resonant creation will have an effect comparable to that of a delta function increment as studied by the nanograv 15-year collaboration, our study indicates that the low-frequency pulsar timing array (pta) data could reveal the aspects of the physics during inflation through the detection of a cosmic background of gravitational waves (gw). | is the nanograv detection evidence of resonant particle creation during inflation? |
by using the gauss-bonnet theorem, the bending angle of light in a static, spherically symmetric and asymptotically flat spacetime has been recently discussed, especially by taking account of the finite distance from a lens object to a light source and a receiver [ishihara, suzuki, ono, asada, phys. rev. d 95, 044017 (2017), 10.1103/physrevd.95.044017]. we discuss a possible extension of the method of calculating the bending angle of light to stationary, axisymmetric and asymptotically flat spacetimes. for this purpose, we consider the light rays on the equatorial plane in the axisymmetric spacetime. we introduce a spatial metric to define the bending angle of light in the finite-distance situation. we show that the proposed bending angle of light is coordinate-invariant by using the gauss-bonnet theorem. the nonvanishing geodesic curvature of the photon orbit with the spatial metric is caused in gravitomagnetism, even though the light ray in the four-dimensional spacetime follows the null geodesic. finally, we consider kerr spacetime as an example in order to examine how the bending angle of light is computed by the present method. the finite-distance correction to the gravitomagnetic deflection angle due to the sun's spin is around a pico-arcsecond level. the finite-distance corrections for sgr a* also are estimated to be very small. therefore, the gravitomagnetic finite-distance corrections for these objects are unlikely to be observed with present technology. | gravitomagnetic bending angle of light with finite-distance corrections in stationary axisymmetric spacetimes |
the free-streaming length of dark matter depends on fundamental dark matter physics, and determines the abundance and concentration of dark matter haloes on sub-galactic scales. using the image positions and flux ratios from eight quadruply imaged quasars, we constrain the free-streaming length of dark matter and the amplitude of the subhalo mass function (shmf). we model both main deflector subhaloes and haloes along the line of sight, and account for warm dark matter free-streaming effects on the mass function and mass-concentration relation. by calibrating the scaling of the shmf with host halo mass and redshift using a suite of simulated haloes, we infer a global normalization for the shmf. we account for finite-size background sources, and marginalize over the mass profile of the main deflector. parametrizing dark matter free-streaming through the half-mode mass mhm, we constrain the thermal relic particle mass mdm corresponding to mhm. at 95 {per cent} ci: mhm < 107.8 m⊙ (m_{dm} > 5.2 {kev}). we disfavour m_{dm} = 4.0 {kev} and m_{dm} = 3.0 {kev} with likelihood ratios of 7:1 and 30:1, respectively, relative to the peak of the posterior distribution. assuming cold dark matter, we constrain the projected mass in substructure between 106 and 109 m⊙ near lensed images. at 68 {per cent} ci, we infer 2.0{-}6.1 × 107 {m_{⊙ }} {kpc^{-2}}, corresponding to mean projected mass fraction \bar{f}_{sub} = 0.035_{-0.017}^{+0.021}. at 95 {per cent} ci, we obtain a lower bound on the projected mass of 0.6 × 107 {m_{⊙ }} {kpc^{-2}}, corresponding to \bar{f}_{sub} > 0.005. these results agree with the predictions of cold dark matter. | warm dark matter chills out: constraints on the halo mass function and the free-streaming length of dark matter with eight quadruple-image strong gravitational lenses |
despite considerable efforts over the past decade, only 34 fast radio bursts—intense bursts of radio emission from beyond our galaxy—have been reported1,2. attempts to understand the population as a whole have been hindered by the highly heterogeneous nature of the searches, which have been conducted with telescopes of different sensitivities, at a range of radio frequencies, and in environments corrupted by different levels of radio-frequency interference from human activity. searches have been further complicated by uncertain burst positions and brightnesses—a consequence of the transient nature of the sources and the poor angular resolution of the detecting instruments. the discovery of repeating bursts from one source3, and its subsequent localization4 to a dwarf galaxy at a distance of 3.7 billion light years, confirmed that the population of fast radio bursts is located at cosmological distances. however, the nature of the emission remains elusive. here we report a well controlled, wide-field radio survey for these bursts. we found 20, none of which repeated during follow-up observations between 185-1,097 hours after the initial detections. the sample includes both the nearest and the most energetic bursts detected so far. the survey demonstrates that there is a relationship between burst dispersion and brightness and that the high-fluence bursts are the nearby analogues of the more distant events found in higher-sensitivity, narrower-field surveys5. | the dispersion-brightness relation for fast radio bursts from a wide-field survey |
primordial black holes (pbhs) generated by gravitational collapse of large primordial overdensities can be a fraction of the observed dark matter. in this paper, we introduce a mechanism to produce a large peak in the primordial power spectrum (pps) in two-field inflationary models characterized by two stages of inflation based on a large non-canonical kinetic coupling. this mechanism is generic to several two-field inflationary models, due to a temporary tachyonic instability of the isocurvature perturbations at the transition between the two stages of inflation. we numerically compute the primordial perturbations from largest scales to the small scales corresponding to that of pbhs using an extension of bingo (bi-spectra and non-gaussianity operator). moreover we numerically compute the stochastic background of gravitational waves (sbgw) produced by second order scalar perturbations within frequencies ranging from nano-hz to khz that covers the observational scales corresponding to pulsar timing arrays, square kilometer array to that of einstein telescope. we discuss the prospect of its detection by these proposed and upcoming gravitational waves experiments. | generating pbhs and small-scale gws in two-field models of inflation |
in the curvaton scenario, the curvature perturbation is generated after inflation at the curvaton decay, which may have a prominent non-gaussian effect. for a model with a nontrivial kinetic term, an enhanced curvature perturbation on a small scale can be realized, which can lead to copious production of primordial black holes (pbhs) and induce secondary gravitational waves (gws). using the probability distribution function (pdf) which takes full nonlinear effects into account, we calculate the pbh formation. we find that under the assumption that thus formed pbhs would not overclose the universe, the non-gaussianity of the curvature perturbation can be well-approximated by the local quadratic form, which can be used to calculate the induced gws. in this model the limit of large non-gaussianity can be reached when the curvaton energy fraction r is small at the moment of curvaton decay. we also show that in the r →1 limit the pdf is similar to that of ultraslow-roll inflation. | primordial black hole formation in nonminimal curvaton scenarios |
the early dark energy (ede) scenario aims to increase the value of the hubble constant (h0) inferred from cosmic microwave background (cmb) data over that found in the standard cosmological model (λ cdm ), via the introduction of a new form of energy density in the early universe. the ede component briefly accelerates cosmic expansion just prior to recombination, which reduces the physical size of the sound horizon imprinted in the cmb. previous work has found that nonzero ede is not preferred by planck cmb power spectrum data alone, which yield a 95% confidence level (c.l.) upper limit fede<0.087 on the maximal fractional contribution of the ede field to the cosmic energy budget. in this paper, we fit the ede model to cmb data from the atacama cosmology telescope (act) data release 4. we find that a combination of act, large-scale planck tt (similar to wmap), planck cmb lensing, and bao data prefers the existence of ede at >99.7 % c .l . : fede=0.09 1-0.036+0.020, with h0=70.9-2.0+1.0 km /s /mpc (both 68% c.l.). from a model-selection standpoint, we find that ede is favored over λ cdm by these data at roughly 3 σ significance. in contrast, a joint analysis of the full planck and act data yields no evidence for ede, as previously found for planck alone. we show that the preference for ede in act alone is driven by its te and ee power spectrum data. the tight constraint on ede from planck alone is driven by its high-ℓ tt power spectrum data. understanding whether these differing constraints are physical in nature, due to systematics, or simply a rare statistical fluctuation is of high priority. the best-fit ede models to act and planck exhibit coherent differences across a wide range of multipoles in te and ee, indicating that a powerful test of this scenario is anticipated with near-future data from act and other ground-based experiments. | atacama cosmology telescope: constraints on prerecombination early dark energy |
we present a new method for consistent, joint analysis of the pre- and post-reconstruction galaxy two-point functions of the boss survey. the post-reconstruction correlation function is used to accurately measure the distance-redshift relation and expansion history, while the pre-reconstruction power spectrum multipoles constrain the broad-band shape and the rate-of-growth of large-scale structure. our technique uses lagrangian perturbation theory to self-consistently work at the level of two-point functions, i.e. directly with the measured data, without approximating the constraints with summary statistics normalized by the drag scale. combining galaxies across the full redshift range and both hemispheres we constrain ωm = 0.303 ± 0.0082, h 0 = 69.23 ± 0.77 and σ8 = 0.733 ± 0.047 within the context of λcdm. these constraints are consistent both with the planck primary cmb anisotropy data and recent cosmic shear surveys. | a new analysis of galaxy 2-point functions in the boss survey, including full-shape information and post-reconstruction bao |
in this paper we present imrphenomxas, a thorough overhaul of the imrphenomd [s. husa et al., phys. rev. d 93, 044006 (2016), 10.1103/physrevd.93.044006; s. khan et al., phys. rev. d 93, 044007 (2016), 10.1103/physrevd.93.044007] waveform model, which describes the dominant l =2 , |m |=2 spherical harmonic mode of nonprecessing coalescing black holes in terms of piecewise closed form expressions in the frequency domain. improvements include in particular the accurate treatment of unequal spin effects, and the inclusion of extreme mass ratio waveforms. imrphenomd has previously been extended to approximately include spin precession [m. hannam et al., phys. rev. lett. 113, 151101 (2014), 10.1103/physrevlett.113.151101] and subdominant spherical harmonics [l. london et al., phys. rev. lett. 120, 161102 (2018), 10.1103/physrevlett.120.161102], and with its extensions it has become a standard tool in gravitational wave parameter estimation. improved extensions of imrphenomxas are discussed in companion papers [c. garcía-quirós et al., phys. rev. d 102, 064002 (2020), 10.1103/physrevd.102.064002; g. pratten et al., arxiv:2004.06503]. | setting the cornerstone for a family of models for gravitational waves from compact binaries: the dominant harmonic for nonprecessing quasicircular black holes |
despite the outstanding achievements of modern cosmology, the classical dispute on the precise value of h0, which is the first ever parameter of modern cosmology and one of the prime parameters in the field, still goes on and on after over half a century of measurements. recently the dispute came to the spotlight with renewed strength owing to the significant tension (at > 3 σ c.l.) between the latest planck determination obtained from the cmb anisotropies and the local (distance ladder) measurement from the hubble space telescope (hst), based on cepheids. in this work, we investigate the impact of the running vacuum model (rvm) and related models on such a controversy. for the rvm, the vacuum energy density ρλ carries a mild dependence on the cosmic expansion rate, i.e. ρλ (h), which allows to ameliorate the fit quality to the overall snia + bao + h (z) + lss + cmb cosmological observations as compared to the concordance λcdm model. by letting the rvm to deviate from the vacuum option, the equation of state w = - 1 continues to be favored by the overall fit. vacuum dynamics also predicts the following: i) the cmb range of values for h0 is more favored than the local ones, and ii) smaller values for σ8 (0). as a result, a better account for the lss structure formation data is achieved as compared to the λcdm, which is based on a rigid (i.e. non-dynamical) λ term. | the h0 tension in light of vacuum dynamics in the universe |
assuming the existence of a local, analytic, unitary uv completion in a poincaré invariant scalar field theory with a mass gap, we derive an infinite number of positivity requirements using the known properties of the amplitude at and away from the forward scattering limit. these take the form of bounds on combinations of the pole subtracted scattering amplitude and its derivatives. in turn, these positivity requirements act as constraints on the operator coefficients in the low energy effective theory. for certain theories these constraints can be used to place an upper bound on the mass of the next lightest state that must lie beyond the low energy effective theory if such a uv completion is to ever exist. | positivity bounds for scalar field theories |
we measure the imprint of primordial baryon acoustic oscillations (baos) in the correlation function of lyα absorption in quasar spectra from the baryon oscillation spectroscopic survey (boss) and the extended boss (eboss) in data release 14 (dr14) of the sloan digital sky survey (sdss)-iv. in addition to 179 965 spectra with absorption in the lyman-α (lyα) region, we use lyα absorption in the lyman-β region of 56 154 spectra for the first time. we measure the hubble distance, dh, and the comoving angular diameter distance, dm, relative to the sound horizon at the drag epoch rd at an effective redshift z = 2.34. using a physical model of the correlation function outside the bao peak, we find dh(2.34)/rd = 8.86 ± 0.29 and dm(2.34)/rd = 37.41 ± 1.86, within 1σ from the flat-λcdm model consistent with cmb anisotropy measurements. with the addition of polynomial "broadband" terms, the results remain within one standard deviation of the cmb-inspired model. combined with the quasar-lyα cross-correlation measurement presented in a companion paper, the bao measurements at z = 2.35 are within 1.7σ of the predictions of this model. | baryon acoustic oscillations at z = 2.34 from the correlations of lyα absorption in eboss dr14 |
mobile gravimetry is important in metrology, navigation, geodesy, and geophysics. atomic gravimeters could be among the most accurate mobile gravimeters, but are currently constrained by being complex and fragile. here, we demonstrate a mobile atomic gravimeter, measuring tidal gravity variations in the laboratory as well as surveying gravity in the field. the tidal gravity measurements achieve a sensitivity of 37 $\mu$gal/$\sqrt{\rm hz}$ and a long-term stability of better than 2 $\mu$gal, revealing ocean tidal loading effects and recording several distant earthquakes. we survey gravity in the berkeley hills with an accuracy of around 0.04 mgal and determine the density of the subsurface rocks from the vertical gravity gradient. with simplicity and sensitivity, our instrument paves the way for bringing atomic gravimeters to field applications. | gravity surveys using a mobile atom interferometer |
we consider the swampland distance and de sitter conjectures, of respective order one parameters λ and c. inspired by the recent trans-planckian censorship conjecture (tcc), we propose a generalization of the distance conjecture, which bounds λ to be a half of the tcc bound for c, i.e. λ ≥1/2 √{2/3 } in 4d. in addition, we propose a correspondence between the two conjectures, relating the tower mass m on the one side to the scalar 1 potential v on the other side schematically as m ∼|v|1/2, in the large distance limit. these proposals suggest a generalization of the scalar weak gravity conjecture, and are supported by a variety of examples. the lower bound on λ is verified explicitly in many cases in the literature. the tcc bound on c is checked as well on ten different no-go theorems, which are worked-out in detail, and v is analysed in the asymptotic limit. in particular, new results on 4d scalar potentials from type ii compactifications are obtained. | the web of swampland conjectures and the tcc bound |
we consider galileon inflation in the effective field theory (eft) framework and examine the possibility for pbh formation during slow roll (sr) to ultra slow roll (usr) transitions. we show that loop corrections to the power spectrum, in this case, do not impose additional constraints on the masses of pbhs produced. we indicate that the remarkable non-renormalization property of galileans due to generalized shift symmetry dubbed as galilean symmetry is responsible for protecting pbh formation from quantum loop corrections. | galileon inflation evades the no-go for pbh formation in the single-field framework |
first-order phase transitions, which take place when the symmetries are predominantly broken (and masses are then generated) through radiative corrections, produce observable gravitational waves and primordial black holes. we provide a model-independent approach that is valid for large-enough supercooling to quantitatively describe these phenomena in terms of few parameters, which are computable once the model is specified. the validity of a previously-proposed approach of this sort is extended here to a larger class of theories. among other things, we identify regions of the parameter space that correspond to the background of gravitational waves recently detected by pulsar timing arrays (nanograv, cpta, epta, ppta) and others that are either excluded by the observing runs of ligo and virgo or within the reach of future gravitational wave detectors. furthermore, we find regions of the parameter space where primordial black holes produced by large over-densities due to such phase transitions can account for dark matter. finally, it is shown how this model-independent approach can be applied to specific cases, including a phenomenological completion of the standard model with right-handed neutrinos and gauged b - l undergoing radiative symmetry breaking. | supercooling in radiative symmetry breaking: theory extensions, gravitational wave detection and primordial black holes |
these lecture notes are based on a course given by mark hindmarsh at the 24th saalburg summer school 2018 and written up by marvin lüben, johannes lumma and martin pauly. the aim is to provide the necessary basics to understand first-order phase transitions in the early universe, to outline how they leave imprints in gravitational waves, and advertise how those gravitational waves could be detected in the future. a first-order phase transition at the electroweak scale is a prediction of many theories beyond the standard model, and is also motivated as an ingredient of some theories attempting to provide an explanation for the matter-antimatter asymmetry in our universe. starting from bosonic and fermionic statistics, we derive boltzmann's equation and generalise to a fluid of particles with field dependent mass. we introduce the thermal effective potential for the field in its lowest order approximation, discuss the transition to the higgs phase in the standard model and beyond, and compute the probability for the field to cross a potential barrier. after these preliminaries, we provide a hydrodynamical description of first-order phase transitions as it is appropriate for describing the early universe. we thereby discuss the key quantities characterising a phase transition, and how they are imprinted in the gravitational wave power spectrum that might be detectable by the space-based gravitational wave detector lisa in the 2030s. | phase transitions in the early universe |
the stochastic signal detected by pulsar timing arrays (ptas) has raised great interest in understanding its physical origin. assuming the signal is a cosmological gravitational-wave background produced by overly large primordial curvature perturbations, we investigate the sound speed resonance effect with an oscillatory behavior using the combined pta data from nanograv 15-yr data set, ppta dr3, and epta dr2. we find that the stochastic signal can be explained by the induced gravitational waves sourced by the sound speed resonance mechanism, with the oscillation frequency f * ∈ [1.51, 4.90] × 10-7hz and the start time of oscillation |τ 0| ∈ [2.05, 106] × 107s. | confronting sound speed resonance with pulsar timing arrays |
we present the results of the most comprehensive survey of the galactic plane in very high-energy (vhe) γ-rays, including a public release of galactic sky maps, a catalog of vhe sources, and the discovery of 16 new sources of vhe γ-rays. the high energy spectroscopic system (h.e.s.s.) galactic plane survey (hgps) was a decade-long observation program carried out by the h.e.s.s. i array of cherenkov telescopes in namibia from 2004 to 2013. the observations amount to nearly 2700 h of quality-selected data, covering the galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. in addition to the unprecedented spatial coverage, the hgps also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% crab flux for point-like sources), and energy range (0.2-100 tev). we constructed a catalog of vhe γ-ray sources from the hgps data set with a systematic procedure for both source detection and characterization of morphology and spectrum. we present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the galactic plane. in total, the resulting hgps catalog contains 78 vhe sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the galactic center region. where possible, we provide a firm identification of the vhe source or plausible associations with sources in other astronomical catalogs. we also studied the characteristics of the vhe sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. we firmly identified 31 sources as pulsar wind nebulae (pwne), supernova remnants (snrs), composite snrs, or gamma-ray binaries. among the 47 sources not yet identified, most of them (36) have possible associations with cataloged objects, notably pwne and energetic pulsars that could power vhe pwne. the source catalog is available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/612/a1 | the h.e.s.s. galactic plane survey |
we study the topological susceptibility in 2 + 1 flavor qcd above the chiral crossover transition temperature using highly improved staggered quark action and several lattice spacings corresponding to temporal extent of the lattice, nτ = 6 , 8 , 10 and 12. we observe very distinct temperature dependences of the topological susceptibility in the ranges above and below 250 mev. while for temperatures above 250 mev, the dependence is found to be consistent with dilute instanton gas approximation, at lower temperatures the fall-off of topological susceptibility is milder. we discuss the consequence of our results for cosmology wherein we estimate the bounds on the axion decay constant and the oscillation temperature if indeed the qcd axion is a possible dark matter candidate. | the topological susceptibility in finite temperature qcd and axion cosmology |
the lyman-α forest 1d flux power spectrum is a powerful probe of several cosmological parameters. assuming a λcdm cosmology including massive neutrinos, we find that the latest sdss dr14 boss and eboss lyman-α forest data is in very good agreement with current weak lensing constraints on (ωm, σ8) and has the same small level of tension with planck. we did not identify a systematic effect in the data analysis that could explain this small tension, but we show that it can be reduced in extended cosmological models where the spectral index is not the same on the very different times and scales probed by cmb and lyman-α data. a particular case is that of a λcdm model including a running of the spectral index on top of massive neutrinos. with combined lyman-α and planck data, we find a slight (3σ) preference for negative running, αs= -0.010 ± 0.004 (68%cl). neutrino mass bounds are found to be robust against different assumptions. in the λcdm model with running, we find ∑ mν <0.11 ev at the 95% confidence level for combined lyman-α and planck (temperature and polarisation) data, or ∑ mν < 0.09 ev when adding cmb lensing and bao data. we further provide strong and nearly model-independent bounds on the mass of thermal warm dark matter. for a conservative configuration consisting of sdss data restricted to z<4.5 combined with xq-100 lyman-α data, we find mx > 5.3 kev (95%cl). | hints, neutrino bounds, and wdm constraints from sdss dr14 lyman-α and planck full-survey data |
we present a multi-messenger measurement of the hubble constant h 0 using the binary-black-hole merger gw170814 as a standard siren, combined with a photometric redshift catalog from the dark energy survey (des). the luminosity distance is obtained from the gravitational wave signal detected by the laser interferometer gravitational-wave observatory (ligo)/virgo collaboration (lvc) on 2017 august 14, and the redshift information is provided by the des year 3 data. black hole mergers such as gw170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object hubble diagram. however, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. here we present the first hubble parameter measurement using a black hole merger. our analysis results in {h}0={75}-32+40 {km} {{{s}}}-1 {mpc}}-1, which is consistent with both sn ia and cosmic microwave background measurements of the hubble constant. the quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s-1 mpc-1, and it depends on the assumed prior range. if we take a broader prior of [10, 220] km s-1 mpc-1, we find {h}0={78}-24+96 {km} {{{s}}}-1 {mpc}}-1 (57% of the prior range). although a weak constraint on the hubble constant from a single event is expected using the dark siren method, a multifold increase in the lvc event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on h 0. | first measurement of the hubble constant from a dark standard siren using the dark energy survey galaxies and the ligo/virgo binary-black-hole merger gw170814 |
we report the first search results for axion dark matter using an 18 t high-temperature superconducting magnet haloscope. the scan frequency ranges from 4.7789 to 4.8094 ghz. no significant signal consistent with the galactic halo dark matter axion is observed. the results set the best upper bound of axion-photon-photon coupling (ga γ γ ) in the mass ranges of 19.764 to 19.771 μ ev (19.863 to 19.890 μ ev ) at 1.5 ×|gaγ γ ksvz| (1.7 ×|gaγ γ ksvz| ), and 19.772 to 19.863 μ ev at 2.7 ×|gaγ γ ksvz| with 90% confidence level, respectively. this remarkable sensitivity in the high mass region of dark matter axion is achieved by using the strongest magnetic field among the existing haloscope experiments and realizing a low-noise amplification of microwave signals using a josephson parametric converter. | searching for invisible axion dark matter with an 18 t magnet haloscope |
we report the detection for the first time in space of three new pure hydrocarbon cycles in tmc-1: c-c3hcch (ethynyl cyclopropenylidene), c-c5h6 (cyclopentadiene), and c-c9h8 (indene). we derive a column density of 3.1 × 1011 cm−2 for the first cycle and similar values, in the range (1−2) × 1013 cm−2, for the second and third. this means that cyclopentadiene and indene, in spite of their large size, are exceptionally abundant, only a factor of five less abundant than the ubiquitous cyclic hydrocarbon c-c3h2. the high abundance found for these two hydrocarbon cycles together with the high abundance previously found for the propargyl radical (ch2cch) and other hydrocarbons, such as vinyl and allenyl acetylene (agúndez et al. 2021, a&a, 647, l10; cernicharo et al. 2021a, a&a, 647, l2; cernicharo et al. 2021b, a&a, 647, l3), start to allow us to quantify the abundant content of hydrocarbon rings in cold dark clouds and to identify the intermediate species that are probably behind the in situ bottom-up synthesis of aromatic cycles in these environments. while c-c3hcch is most likely formed through the reaction between the radical cch and c-c3h2, the high observed abundances of cyclopentadiene and indene are difficult to explain through currently proposed chemical mechanisms. further studies are needed to identify how five- and six-membered rings are formed under the cold conditions of a cloud such as tmc-1. based on observations carried out with the yebes 40 m telescope (projects 19a003, 20a014, 20d023, and 21a011) and the institut de radioastronomie millimétrique (iram) 30 m telescope. the 40 m radio telescope at yebes observatory is operated by the spanish geographic institute (ign; ministerio de transportes, movilidad y agenda urbana). iram is supported by insu/cnrs (france), mpg (germany), and ign (spain). | pure hydrocarbon cycles in tmc-1: discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene |
we present cosmological constraints from a joint analysis of the pre- and post-reconstruction galaxy power spectrum multipoles from the final data release of the baryon oscillation spectroscopic survey (boss). geometric constraints are obtained from the positions of bao peaks in reconstructed spectra, which are analyzed in combination with the unreconstructed spectra in a full-shape (fs) likelihood using a joint covariance matrix, giving stronger parameter constraints than fs-only or bao-only analyses. we introduce a new method for obtaining constraints from reconstructed spectra based on a correlated theoretical error, which is shown to be simple, robust, and applicable to any flavor of density-field reconstruction. assuming λcdm with massive neutrinos, we analyze clustering data from two redshift bins zeff=0.38,0.61 and obtain 1.6% constraints on the hubble constant h0, using only a single prior on the current baryon density ωb from big bang nucleosynthesis (bbn) and no knowledge of the power spectrum slope ns. this gives h0 = 68.6±1.1 km s-1mpc-1, with the inclusion of bao data sharpening the measurement by 40%, representing one of the strongest current constraints on h0 independent of cosmic microwave background data, comparable with recent constraints using bao data in combination with other data-sets. restricting to the best-fit slope ns from planck (but without additional priors on the spectral shape), we obtain a 1% h0 measurement of 67.8± 0.7 km s-1mpc-1. finally, we find strong constraints on the cosmological parameters from a joint analysis of the fs, bao, and planck data. this sets new bounds on the sum of neutrino masses ∑ mν < 0.14 ev (at 95% confidence) and the effective number of relativistic degrees of freedom neff = 2.90+0.15-0.16, though contours are not appreciably narrowed by the inclusion of bao data. | combining full-shape and bao analyses of galaxy power spectra: a 1.6% cmb-independent constraint on h0 |
we compile an updated list of 38 measurements of the hubble parameter h(z) between redshifts 0.07 ≤ z ≤ 2.36 and use them to place constraints on model parameters of constant and time-varying dark energy cosmological models, both spatially flat and curved. we use five models to measure the redshift of the cosmological deceleration-acceleration transition, zda, from these h(z) data. within the error bars, the measured zda are insensitive to the model used, depending only on the value assumed for the hubble constant h0. the weighted mean of our measurements is zda = 0.72 ± 0.05 (0.84 ± 0.03) for h0 = 68 ± 2.8 (73.24 ± 1.74) km s-1 mpc-1 and should provide a reasonably model-independent estimate of this cosmological parameter. the h(z) data are consistent with the standard spatially flat λcdm cosmological model but do not rule out nonflat models or dynamical dark energy models. | hubble parameter measurement constraints on the redshift of the deceleration-acceleration transition, dynamical dark energy, and space curvature |
we search for gravitational-wave signals produced by cosmic strings in the advanced ligo and virgo full o3 dataset. search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. a template-based search for short-duration transient signals does not yield a detection. we also use the stochastic gravitational-wave background energy density upper limits derived from the o3 data to constrain the cosmic string tension g μ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. additionally, we develop and test a third model that interpolates between these two models. our results improve upon the previous ligo-virgo constraints on g μ by 1 to 2 orders of magnitude depending on the model that is tested. in particular, for the one-loop distribution model, we set the most competitive constraints to date: g μ ≲4 ×10-15. in the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models. | constraints on cosmic strings using data from the third advanced ligo-virgo observing run |
among the most important goals in cosmology is detecting and quantifying small (m_halo∼eq 10^{6-9} m_{⊙}) dark matter (dm) subhaloes. current probes around the milky way (mw) are most sensitive to such substructure within ∼20 kpc of the halo centre, where the galaxy contributes significantly to the potential. we explore the effects of baryons on subhalo populations in λcdm using cosmological zoom-in baryonic simulations of mw-mass haloes from the latte simulation suite, part of the feedback in realistic environments (fire) project. specifically, we compare simulations of the same two haloes run using (1) dm-only (dmo), (2) full baryonic physics and (3) dm with an embedded disc potential grown to match the fire simulation. relative to baryonic simulations, dmo simulations contain ∼2 × as many subhaloes within 100 kpc of the halo centre; this excess is ≳5 × within 25 kpc. at z = 0, the baryonic simulations are completely devoid of subhaloes down to 3× 10^6 m_{⊙} within 15 kpc of the mw-mass galaxy, and fewer than 20 surviving subhaloes have orbital pericentres <20 kpc. despite the complexities of baryonic physics, the simple addition of an embedded central disc potential to dmo simulations reproduces this subhalo depletion, including trends with radius, remarkably well. thus, the additional tidal field from the central galaxy is the primary cause of subhalo depletion. subhaloes on radial orbits that pass close to the central galaxy are preferentially destroyed, causing the surviving population to have tangentially biased orbits compared to dmo predictions. our method of embedding a potential in dmo simulations provides a fast and accurate alternative to full baryonic simulations, thus enabling suites of cosmological simulations that can provide accurate and statistical predictions of substructure populations. | not so lumpy after all: modelling the depletion of dark matter subhaloes by milky way-like galaxies |
the widefield askap l-band legacy all-sky blind survey (wallaby) is a next-generation survey of neutral hydrogen (hi) in the local universe. it uses the widefield, high-resolution capability of the australian square kilometer array pathfinder (askap), a radio interferometer consisting of 36 ×12 -m dishes equipped with phased-array feeds (pafs), located in an extremely radio-quiet zone in western australia. wallaby aims to survey three-quarters of the sky (-90∘<δ <+30∘) to a redshift of z ≲0.26 , and generate spectral line image cubes at ∼30 arcsec resolution and ∼1.6 mjy beam-1 per 4 km s-1 channel sensitivity. askap's instantaneous field of view at 1.4 ghz, delivered by the paf's 36 beams, is about 30 sq deg. at an integrated signal-to-noise ratio of five, wallaby is expected to detect around half a million galaxies with a mean redshift of z ∼0.05 (∼200 mpc). the scientific goals of wallaby include: (a) a census of gas-rich galaxies in the vicinity of the local group; (b) a study of the hi properties of galaxies, groups and clusters, in particular the influence of the environment on galaxy evolution; and (c) the refinement of cosmological parameters using the spatial and redshift distribution of low-bias gas-rich galaxies. for context we provide an overview of recent and planned large-scale hi surveys. combined with existing and new multi-wavelength sky surveys, wallaby will enable an exciting new generation of panchromatic studies of the local universe. — first results from the wallaby pilot survey are revealed, with initial data products publicly available in the csiro askap science data archive (casda). | wallaby - an ska pathfinder hi survey |
our understanding of the state of the universe between the end of inflation and big bang nucleosynthesis (bbn) is incomplete. the dynamics at the end of inflation are rich and a potential source of observational signatures. reheating, the energy transfer between the inflaton and standard model fields (possibly through intermediaries) and their subsequent thermalization, can provide clues to how inflation fits in with known high-energy physics. we provide an overview of our current understanding of the nonperturbative, nonlinear dynamics at the end of inflation, some salient features of realistic particle physics models of reheating, and how the universe reaches a thermal state before bbn. in addition, we review the analytical and numerical tools available in the literature to study preheating and reheating and discuss potential observational signatures from this fascinating era. | nonperturbative dynamics of reheating after inflation: a review |
in the past twenty years, the reconnaissance of 12co and 13co emission in the milky way by single-dish millimeter-wave telescopes has expanded our view and understanding of interstellar molecular gas. we enumerate the major surveys of co emission along the galactic plane and summarize the various approaches that leverage these data to determine the large-scale distribution of molecular gas: its radial and vertical distributions, its concentration into clouds, and its relationship to spiral structure. the integrated properties of molecular clouds are compiled from catalogs derived from the co surveys using uniform assumptions regarding the galactic rotation curve, solar radius, and the co-to-h2 conversion factor. we discuss the radial variations of cloud surface brightness, the distributions of cloud mass and size, and scaling relations between velocity dispersion, cloud size, and surface density that affirm that the larger clouds are gravitationally bound. measures of density structure and gas kinematics within nearby, well-resolved clouds are examined and attributed to the effects of magnetohydrodynamic turbulence. we review the arguments for short, intermediate, and long molecular lifetimes based on the observational record. the review concludes with questions that shall require further observational attention. | molecular clouds in the milky way |
we compute the tree-level late-time graviton four-point correlation function, and the related quartic wavefunction coefficient, for einstein gravity in de sitter spacetime. we derive this result in several ways: by direct calculation, using the in-in formalism and the wavefunction of the universe; by a heuristic derivation leveraging the flat space wave-function coefficient; and by using the boostless cosmological bootstrap, in particular the combination of the cosmological optical theorem, the amplitude limit, and the manifestly local test. we find agreement among the different methods. | the graviton four-point function in de sitter space |
the λcdm cosmology passes demanding tests that establish it as a good approximation to reality. the theory is incomplete, of course, and open issues are being examined in active research programs. i offer a review of less widely discussed anomalies that might also point to hints to a still better cosmological theory if more closely examined. | anomalies in physical cosmology |
motivated by the recently reported anomaly in w boson mass by the cdf collaboration with 7σ statistical significance, we consider a singlet-doublet (sd) majorana fermion dark matter (dm) model where the required correction to w boson mass arises from radiative corrections induced by sd fermions. while a single generation of sd fermions, odd under an unbroken z2 symmetry, can not explain the w boson mass anomaly while being consistent with dm phenomenology, two generations of sd fermions can do so with the heavier generation playing the dominant role in w-mass correction and lighter generation playing the role in dm phenomenology. additionally, such multiple generations of sd fermions can also generate light neutrino masses radiatively if a z2-odd singlet scalar is included. | singlet-doublet fermion origin of dark matter, neutrino mass and w-mass anomaly |
to account for the dark-matter content in our universe, postinflationary scenarios predict for the qcd axion a mass in the range (10 - 103) μ ev . searches with haloscope experiments in this mass range require the monitoring of resonant cavity modes with frequency above 5 ghz, where several experimental limitations occur due to linear amplifiers, small volumes, and low quality factors of copper resonant cavities. in this paper, we deal with the last issue, presenting the result of a search for galactic axions using a haloscope based on a 36 cm3 nbti superconducting cavity. the cavity worked at t =4 k in a 2 t magnetic field and exhibited a quality factor q0=4.5 ×105 for the tm010 mode at 9 ghz. with such values of q , the axion signal is significantly increased with respect to copper cavity haloscopes. operating this setup, we set the limit ga γ γ<1.03 ×10-12 gev-1 on the axion photon coupling for a mass of about 37 μ ev . a comprehensive study of the nbti cavity at different magnetic fields, temperatures, and frequencies is also presented. | galactic axions search with a superconducting resonant cavity |
we present a catalog of sources detected above 10 gev by the fermi large area telescope (lat) in the first 7 years of data using the pass 8 event-level analysis. this is the third catalog of hard fermi-lat sources (3fhl), containing 1556 objects characterized in the 10 gev-2 tev energy range. the sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous lat catalog at the same energies (1fhl). the vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (z > 2). of the sources, 8% have galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). the high-latitude sky and the galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10-11 ph cm-2 s-1, respectively (this is approximately 0.5% and 1% of the crab nebula flux above 10 gev). the catalog includes 214 new γ-ray sources. the substantial increase in the number of photons (more than 4 times relative to 1fhl and 10 times to 2fhl) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. furthermore, we estimate that for the same flux limit of 10-12 erg cm-2 s-1, the energy range above 10 gev has twice as many sources as the range above 50 gev, highlighting the importance, for future cherenkov telescopes, of lowering the energy threshold as much as possible. | 3fhl: the third catalog of hard fermi-lat sources |
the origin of ultrahigh-energy cosmic rays (uhecrs) is a half-century-old enigma1. the mystery has been deepened by an intriguing coincidence: over ten orders of magnitude in energy, the energy generation rates of uhecrs, pev neutrinos and isotropic sub-tev γ-rays are comparable, which hints at a grand unified picture2. here we report that powerful black hole jets in aggregates of galaxies can supply the common origin for all of these phenomena. once accelerated by a jet, low-energy cosmic rays confined in the radio lobe are adiabatically cooled; higher-energy cosmic rays leaving the source interact with the magnetized cluster environment and produce neutrinos and γ-rays; the highest-energy particles escape from the host cluster and contribute to the observed cosmic rays above 100 pev. the model is consistent with the spectrum, composition and isotropy of the observed uhecrs, and also explains the icecube neutrinos and the non-blazar component of the fermi γ-ray background, assuming a reasonable energy output from black hole jets in clusters. | linking high-energy cosmic particles by black-hole jets embedded in large-scale structures |
the question of whether cosmic microwave background (cmb) temperature and polarization data from planck favor a spatially closed universe with curvature parameter ωk < 0 has been the subject of recent intense discussions. attempts to break the geometrical degeneracy combining planck data with external data sets such as baryon acoustic oscillation (bao) measurements all point toward a spatially flat universe at the cost of significant tensions with planck, which makes the resulting data set combination problematic. settling this issue requires identifying a data set that can break the geometrical degeneracy while avoiding these tensions. we argue that cosmic chronometers (ccs), measurements of the expansion rate h(z) from the relative ages of massive early-type passively evolving galaxies, are the data set we are after. furthermore, ccs come with the additional advantage of being virtually free of cosmological model assumptions. combining planck 2018 cmb temperature and polarization data with the latest ccs, we break the geometrical degeneracy and find ωk = -0.0054 ± 0.0055, consistent with a spatially flat universe and competitive with the planck+bao constraint. our results are stable against minimal parameter space extensions and cc systematics, and we find no substantial tension between planck and cc data within a nonflat universe, making the resulting combination reliable. our results allow us to assert with confidence that the universe is spatially flat to the ${ \mathcal o }({10}^{-2})$ level, a finding that might possibly settle the ongoing spatial curvature debate and lends even more support to the already very successful inflationary paradigm. | eppur è piatto? the cosmic chronometers take on spatial curvature and cosmic concordance |
most of the celestial γ rays detected by the large area telescope (lat) on board the fermi gamma-ray space telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. here, we describe the development of the galactic interstellar emission model (giem), which is the standard adopted by the lat collaboration and is publicly available. this model is based on a linear combination of maps for interstellar gas column density in galactocentric annuli and for the inverse-compton emission produced in the galaxy. in the giem, we also include large-scale structures like loop i and the fermi bubbles. the measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with galactocentric distance beyond 5 kpc from the galactic center. the measurements also suggest a softening of the proton spectrum with galactocentric distance. we observe that the fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20° and we observe an enhanced emission toward their base extending in the north and south galactic directions and located within ∼4° of the galactic center. | development of the model of galactic interstellar emission for standard point-source analysis of fermi large area telescope data |
the tension between early and late universe probes of the hubble constant has motivated various new flrw cosmologies. here, we reanalyse the hubble tension with a recent age of the universe constraint. this allows us to restrict attention to matter and a dark energy sector that we treat without assuming a specific model. assuming analyticity of the hubble parameter h(z), and a generic low redshift modification to flat λcdm, we find that low redshift data (z ≲ 2.5) and well-motivated priors only permit a dark energy sector close to the cosmological constant λ. this restriction rules out late universe modifications within flrw. we show that early universe physics that alters the sound horizon can yield an upper limit of h0 ~ 71 ± 1 km s-1 mpc-1. since various local determinations may be converging to h0 ~ 73 km s-1 mpc-1, a breakdown of the flrw framework is a plausible resolution. we outline how future data, in particular strongly lensed quasar data, could also provide further confirmations of such a resolution. | does hubble tension signal a breakdown in flrw cosmology? |
recent pulsar timing data reported by the nanograv collaboration may indicate the existence of a stochastic gravitational wave background around f ∼10-8 hz. we explore a possibility to generate such low-frequency gravitational waves from a dark sector phase transition. assuming that the dark sector is completely decoupled from the visible sector except via the gravitational interaction, we find that some amount of dark radiation should remain until present. the nanograv data implies that the amount of dark radiation is close to the current upper bound, which may help mitigate the so-called hubble tension. if the existence of dark radiation is not confirmed in the future cmb-s4 experiment, it would imply the existence of new particles feebly interacting with the standard model sector at an energy scale of o (1 - 100) mev. | gravitational waves and dark radiation from dark phase transition: connecting nanograv pulsar timing data and hubble tension |
we derive a set of no-go theorems and yes-go examples for the parity-odd primordial trispectrum of curvature perturbations. we work at tree-level in the decoupling limit of the effective field theory of inflation and assume scale invariance and a bunch-davies vacuum. we show that the parity-odd scalar trispectrum vanishes in the presence of any number of scalar fields with arbitrary mass and any parity-odd scalar correlator vanishes in the presence of any number of spinning fields with massless de sitter mode functions, in agreement with the findings of liu, tong, wang and xianyu [1]. the same is true for correlators with an odd number of conformally-coupled external fields. we derive these results using both the (boostless) cosmological bootstrap, in particular the cosmological optical theorem, and explicit perturbative calculations. we then discuss a series of yes-go examples by relaxing the above assumptions one at the time. in particular, we provide explicit results for the parity-odd trispectrum for (i) violations of scale invariance in single-clock inflation, (ii) the modified dispersion relation of the ghost condensate (non-bunch-davies vacuum), and (iii) interactions with massive spinning fields. our results establish the parity-odd trispectrum as an exceptionally sensitive probe of new physics beyond vanilla inflation. | parity violation in the scalar trispectrum: no-go theorems and yes-go examples |
we present a dedicated complementarity study of gravitational wave and collider measurements of the simplest extension of the higgs sector: the singlet scalar augmented standard model. we study the following issues: ( i) the electroweak phase transition patterns admitted by the model, and the proportion of parameter space for each pattern; ( ii) the regions of parameter space that give detectable gravitational waves at future space-based detectors; and ( iii) the current and future collider measurements of di-higgs production, as well as searches for a heavy weak diboson resonance, and how these searches interplay with regions of parameter space that exhibit strong gravitational wave signals. we carefully investigate the behavior of the normalized energy released during the phase transition as a function of the model parameters, address subtle issues pertaining to the bubble wall velocity, and provide a description of different fluid velocity profiles. on the collider side, we identify the subset of points that are most promising in terms of di-higgs and weak diboson production studies while also giving detectable signals at lisa, setting the stage for future benchmark points that can be used by both communities. | collider and gravitational wave complementarity in exploring the singlet extension of the standard model |
a model of cosmological inflation is proposed in which field space is a hyperbolic plane. the inflaton never slow-rolls, and instead orbits the bottom of the potential, buoyed by a centrifugal force. though initial velocities redshift away during inflation, in negatively curved spaces angular momentum naturally starts exponentially large and remains relevant throughout. quantum fluctuations produce perturbations that are adiabatic and approximately scale invariant; strikingly, in a certain parameter regime the perturbations can grow double exponentially during horizon crossing. | hyperbolic inflation |
we search for evidence of parity-violating physics in the planck 2018 polarization data and report on a new measurement of the cosmic birefringence angle β . the previous measurements are limited by the systematic uncertainty in the absolute polarization angles of the planck detectors. we mitigate this systematic uncertainty completely by simultaneously determining β and the angle miscalibration using the observed cross-correlation of the e - and b -mode polarization of the cosmic microwave background and the galactic foreground emission. we show that the systematic errors are effectively mitigated and achieve a factor-of-2 smaller uncertainty than the previous measurement, finding β =0.35 ±0.14 deg (68% c.l.), which excludes β =0 at 99.2% c.l. this corresponds to the statistical significance of 2.4 σ . | new extraction of the cosmic birefringence from the planck 2018 polarization data |
we present the first ge-based constraints on sub-mev /c2 dark matter (dm) particles interacting with electrons using a 33.4 g ge cryogenic detector with a 0.53 electron-hole pair (rms) resolution, operated underground at the laboratoire souterrain de modane. competitive constraints are set on the dm-electron scattering cross section, as well as on the kinetic mixing parameter of dark photons down to 1 ev /c2 . in particular, the most stringent limits are set for dark photon dm in the 6 to 9 ev /c2 range. these results demonstrate the high relevance of ge cryogenic detectors for the search of dm-induced ev-scale electron signals. | first germanium-based constraints on sub-mev dark matter with the edelweiss experiment |
inflation is the leading theory of the first instant of the universe. inflation, which postulates that the universe underwent a period of rapid expansion an instant after its birth, provides convincing explanation for cosmological observations. recent advancements in detector technology have opened opportunities to explore primordial gravitational waves generated by the inflation through "b-mode" (divergent-free) polarization pattern embedded in the cosmic microwave background anisotropies. if detected, these signals would provide strong evidence for inflation, point to the correct model for inflation, and open a window to physics at ultra-high energies. litebird is a satellite mission with a goal of detecting degree-and-larger-angular-scale b-mode polarization. litebird will observe at the second lagrange point with a 400 mm diameter telescope and 2622 detectors. it will survey the entire sky with 15 frequency bands from 40 to 400 ghz to measure and subtract foregrounds. the us litebird team is proposing to deliver sub-kelvin instruments that include detectors and readout electronics. a lenslet-coupled sinuous antenna array will cover low-frequency bands (40-235 ghz) with four frequency arrangements of trichroic pixels. an orthomode-transducer-coupled corrugated horn array will cover high-frequency bands (280-402 ghz) with three types of single frequency detectors. the detectors will be made with transition edge sensor (tes) bolometers cooled to a 100 milli-kelvin base temperature by an adiabatic demagnetization refrigerator. the tes bolometers will be read out using digital frequency multiplexing with superconducting quantum interference device (squid) amplifiers. up to 78 bolometers will be multiplexed with a single squid amplifier. we report on the sub-kelvin instrument design and ongoing developments for the litebird mission. | the litebird satellite mission: sub-kelvin instrument |
there has been growing interest in $f(q)$ gravity, which has led to significant advancements in the field. however, it is important to note that most studies in this area were based on the coincident gauge, thus overlooking the impact of the connection degrees of freedom. in this work, we pay special attention to the connection when studying perturbations in general teleparallel, metric teleparallel, and symmetric teleparallel theories of gravity. we do not just examine perturbations in the metric, but also in the affine connection. to illustrate this, we investigate cosmological perturbations in $f(g)$, $f(t)$, and $f(q)$ gravity with and without matter in form of an additional scalar field for spatially flat and curved flrw geometries. our perturbative analysis reveals that for general $f(q)$ backgrounds, there are up to seven degrees of freedom, depending on the background connection. this is in perfect agreement with the upper bound on degrees of freedom established for the first time in $\href{https://doi.org/10.1002/prop.202300185}{fortschr. phys. 2023, 2300185}$. in $f(g)$ and $f(t)$ gravity theories, only two tensor modes propagate in the gravity sector on generic curved cosmological backgrounds, indicating strong coupling problems. in the context of $f(q)$ cosmology, we find that for a particular background connection, where all seven modes propagate, there is at least one ghost degree of freedom. for all other choices of the connection the ghost can be avoided at the cost of strong coupling problem, where only four degrees of freedom propagate. hence, all of the cosmologies within the teleparallel families of theories in form of $f(g)$, $f(t)$, and $f(q)$ suffer either from strong coupling or from ghost instabilities. a direct coupling of the matter field to the connection or non-minimal couplings might alter these results. | cosmological teleparallel perturbations |
we present early results regarding the morphological and structural properties of galaxies seen with the james webb space telescope (jwst) at z > 3 in the early release observations toward the smacs 0723 cluster field. using jwst we investigate, for the first time, the optical morphologies of a significant number of z > 3 galaxies with accurate photometric redshifts in this field to determine the form of galaxy structure in the relatively early universe. we use visual morphologies and morfometryka measures to perform quantitative morphology measurements, both parametric with light profile fitting (sérsic indices) and nonparametric (concentration, asymmetry, and smoothness (cas) values). using these, we measure the relative fraction of disk, spheroidal, and peculiar galaxies at 3 < z < 8. we discover the surprising result that at z > 1.5 disk galaxies dominate the overall fraction of morphologies, with a factor of ~10 relative higher number of disk galaxies than seen by the hubble space telescope at these redshifts. our visual morphological estimates of galaxies align closely with their locations in cas parameter space and their sérsic indices. | panic! at the disks: first rest-frame optical observations of galaxy structure at z > 3 with jwst in the smacs 0723 field |
within the lambda cold dark matter (λcdm) model, measurements from recent cosmic microwave background (cmb) and weak lensing (wl) surveys have uncovered a ~3σ disagreement in the inferred value of the parameter $s_8 \equiv \sigma _8\sqrt{\omega _\mathrm{ m}/0.3}$, quantifying the amplitude of late-time matter fluctuations. before questioning whether the s8 discrepancy calls for new physics, it is important to assess the view of measurements other than cmb and wl ones on the discrepancy. here, we examine the role of measurements of the growth rate f(z) in arbitrating the s8 discrepancy, considering measurements of fσ8(z) from redshift-space distortions (rsds). our baseline analysis combines rsd measurements with geometrical measurements from baryon acoustic oscillations (bao) and type ia supernovae (sneia), given the key role of the latter in constraining ωm. from this combination and within the λcdm model, we find $s_8 = 0.762^{+0.030}_{-0.025}$, and quantify the agreement between rsd + bao + sneia and planck to be at the 2.2σ level: the mild disagreement is therefore compatible with a statistical fluctuation. we discuss combinations of rsd measurements with other data sets, including the eg statistic. this combination increases the discrepancy with planck, but we deem it significantly less robust. our earlier results are stable against an extension where we allow the dark energy equation of state w to vary. we conclude that, from the point of view of combined growth rate and geometrical measurements, there are hints, but no strong evidence yet, for the planck λcdm cosmology overpredicting the amplitude of matter fluctuations at redshifts z ≲ 1. from this perspective, it might therefore still be premature to claim the need for new physics from the s8 discrepancy. | arbitrating the s8 discrepancy with growth rate measurements from redshift-space distortions |
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