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primordial black holes formed in the early universe via gravitational collapse of over-dense regions may contribute a significant amount to the present dark matter relic density. inflation provides a natural framework for the production mechanism of primordial black holes. for example, single field inflation models with a fine-tuned scalar potential may exhibit a period of ultra-slow roll, during which the curvature perturbation may be enhanced to become seeds of the primordial black holes formed as the corresponding scales reenter the horizon. in this work, we propose an alternative mechanism for the primordial black hole formation. we consider a model in which a scalar field is coupled to the gauss-bonnet term and show that primordial black holes may be seeded when a scalar potential term and the gauss-bonnet coupling term are nearly balanced. large curvature perturbation in this model not only leads to the production of primordial black holes, but it also sources gravitational waves at the second order. we calculate the present density parameter of the gravitational waves and discuss the detectability of the signals by comparing them with sensitivity bounds of future gravitational wave experiments. | primordial black holes from gauss-bonnet-corrected single field inflation |
the standard model could be self-consistent up to the planck scale according to the present measurements of the higgs boson mass and top quark yukawa coupling. it is therefore possible that new physics is only coupled to the standard model through planck suppressed higher dimensional operators. in this case the weakly interacting massive particle miracle is a mirage, and instead minimality as dictated by occam's razor would indicate that dark matter is related to the planck scale, where quantum gravity is anyway expected to manifest itself. assuming within this framework that dark matter is a planckian interacting massive particle, we show that the most natural mass larger than 0.01 mp is already ruled out by the absence of tensor modes in the cosmic microwave background (cmb). this also indicates that we expect tensor modes in the cmb to be observed soon for this type of minimal dark matter model. finally, we touch upon the kaluza-klein graviton mode as a possible realization of this scenario within uv complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. this paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark matter. | planckian interacting massive particles as dark matter |
the λcdm model provides a good fit to most astronomical observations but harbors large areas of phenomenology and ignorance. with the improvements in the precision and number of observations, discrepancies between key cosmological parameters of this model have emerged. among them, the most notable tension is the 4σ to 6σ deviation between the hubble constant (h0) estimations measured by the local distance ladder and the cosmic microwave background (cmb) measurement. in this review, we revisit the h0 tension based on the latest research and sort out evidence from solutions to this tension that might imply new physics beyond the λcdm model. the evidence leans more towards modifying the late-time universe. | hubble tension: the evidence of new physics |
the mysterious dark energy remains one of the greatest puzzles of modern science. current detections for it are mostly indirect. the spacetime effects of dark energy can be locally described by the sds wmetric. understanding these local effects exactly is an essential step toward the direct probe of dark energy. from first principles, we prove that dark energy can exert a repulsive dark force on astrophysical scales, different from the newtonian attraction of both visible and dark matter. one way of measuring local effects of dark energy is through the gravitational deflection of light. we geometrize the bending of light in any curved static spacetime. first of all, we define a generalized deflection angle, referred to as the gaussian deflection angle, in a mathematically strict and conceptually clean way. basing on the gauss-bonnet theorem, we then prove that the gaussian deflection angle is equivalent to the surface integral of the gaussian curvature over a chosen lensing patch. as an application of the geometrization, we study the problem of whether dark energy affects the bending of light and provide a strict solution to this problem in the sds wspacetime. according to this solution, we propose a method to overcome the difficulty of measuring local dark energy effects. exactly speaking, we find that the lensing effect of dark energy can be enhanced by 14 orders of magnitude when properly choosing the lensing patch in certain cases. it means that we can probe the existence and nature of dark energy directly in our solar system. this points to an exciting direction to help unraveling the great mystery of dark energy. | geometrization of light bending and its application to sds wspacetime |
context. the agn bolometric correction is a key element for understanding black hole (bh) demographics and computing accurate bh accretion histories from agn luminosities. however, current estimates still differ from each other by up to a factor of two to three, and rely on extrapolations at the lowest and highest luminosities.aims: here we revisit this fundamental question by presenting general hard x-ray (kx) and optical (ko) bolometric corrections, computed by combining several agn samples spanning the widest (about 7 dex) luminosity range ever used for this type of studies.methods: we analysed a total of ∼1000 type 1 and type 2 agn for which we performed a dedicated sed-fitting.results: we provide a bolometric correction separately for type 1 and type 2 agn; the two bolometric corrections agree in the overlapping luminosity range. based on this we computed for the first time a universal bolometric correction for the whole agn sample (both type 1 and type 2). we found that kx is fairly constant at log(lbol/l⊙) < 11, while it increases up to about one order of magnitude at log(lbol/l⊙) ∼ 14.5. a similar increasing trend has been observed when its dependence on either the eddington ratio or the bh mass is considered, while no dependence on redshift up to z ∼ 3.5 has been found. in contrast, the optical bolometric correction appears to be fairly constant (i.e. ko ∼ 5) regardless of the independent variable. we also verified that our bolometric corrections correctly predict the agn bolometric luminosity functions. according to this analysis, our bolometric corrections can be applied to the whole agn population in a wide range of luminosity and redshift. | universal bolometric corrections for active galactic nuclei over seven luminosity decades |
photometric redshifts are a key component of many science objectives in the hyper suprime-cam subaru strategic program (hsc-ssp). in this paper, we describe and compare the codes used to compute photometric redshifts for hsc-ssp, how we calibrate them, and the typical accuracy we achieve with the hsc five-band photometry (grizy). we introduce a new point estimator based on an improved loss function and demonstrate that it works better than other commonly used estimators. we find that our photo-z's are most accurate at 0.2 ≲ zphot ≲ 1.5, where we can straddle the 4000 å break. we achieve σ[δzphot/(1 + zphot)] ∼ 0.05 and an outlier rate of about 15% for galaxies down to i = 25 within this redshift range. if we limit ourselves to a brighter sample of i < 24, we achieve σ ∼ 0.04 and ∼8% outliers. our photo-z's should thus enable many science cases for hsc-ssp. we also characterize the accuracy of our redshift probability distribution function (pdf) and discover that some codes over-/underestimate the redshift uncertainties, which has implications for n(z) reconstruction. our photo-z products for the entire area in public data release 1 are publicly available, and both our catalog products (such as point estimates) and full pdfs can be retrieved from the data release site, "https://hsc-release.mtk.nao.ac.jp/". | photometric redshifts for hyper suprime-cam subaru strategic program data release 1 |
we present a suite of 18 synthetic sky catalogs designed to support science analysis of galaxies in the dark energy survey year 1 (des y1) data. for each catalog, we use a computationally efficient empirical approach, addgals, to embed galaxies within light-cone outputs of three dark matter simulations that resolve halos with masses above ~5x10^12 h^-1 m_sun at z <= 0.32 and 10^13 h^-1 m_sun at z~2. the embedding method is tuned to match the observed evolution of galaxy counts at different luminosities as well as the spatial clustering of the galaxy population. galaxies are lensed by matter along the line of sight --- including magnification, shear, and multiple images --- using calclens, an algorithm that calculates shear with 0.42 arcmin resolution at galaxy positions in the full catalog. the catalogs presented here, each with the same lcdm cosmology (denoted buzzard), contain on average 820 million galaxies over an area of 1120 square degrees with positions, magnitudes, shapes, photometric errors, and photometric redshift estimates. we show that the weak-lensing shear catalog, redmagic galaxy catalogs and redmapper cluster catalogs provide plausible realizations of the same catalogs in the des y1 data by comparing their magnitude, color and redshift distributions, angular clustering, and mass-observable relations, making them useful for testing analyses that use these samples. we make public the galaxy samples appropriate for the des y1 data, as well as the data vectors used for cosmology analyses on these simulations. | the buzzard flock: dark energy survey synthetic sky catalogs |
quantum scale symmetry is the realization of scale invariance in a quantum field theory. no parameters with dimension of length or mass are present in the quantum effective action. quantum scale symmetry is generated by quantum fluctuations via the presence of fixed points for running couplings. as for any global symmetry, the ground state or cosmological state may be scale invariant or not. spontaneous breaking of scale symmetry leads to massive particles and predicts a massless goldstone boson. a massless particle spectrum follows from scale symmetry of the effective action only if the ground state is scale symmetric. approximate scale symmetry close to a fixed point leads to important predictions for observations in various areas of fundamental physics. we review consequences of scale symmetry for particle physics, quantum gravity and cosmology. for particle physics, scale symmetry is closely linked to the tiny ratio between the fermi scale of weak interactions and the planck scale for gravity. for quantum gravity, scale symmetry is associated to the ultraviolet fixed point which allows for a non-perturbatively renormalizable quantum field theory for all known interactions. the interplay between gravity and particle physics at this fixed point permits to predict couplings of the standard model or other "effective low energy models" for momenta below the planck mass. in particular, quantum gravity determines the ratio of higgs boson mass and top quark mass. in cosmology, approximate scale symmetry explains the almost scale-invariant primordial fluctuation spectrum which is at the origin of all structures in the universe. the pseudo-goldstone boson of spontaneously broken approximate scale symmetry may be responsible for dynamical dark energy and a solution of the cosmological constant problem. | quantum scale symmetry |
we study the theory and phenomenology of massive spin-2 fields during the inflation with nonzero background chemical potential, and extend the cosmological collider physics to tensor modes. we identify a unique dimension-5 and parity-violating chemical potential operator for massive spin-2 fields, which leads to a ghost-free linear theory propagating one scalar mode and two tensor modes. the chemical potential greatly boosts the production of one tensor mode even for very heavy spin-2 particles, and thereby leads to large and distinct cosmological collider signals for massive spin-2 particles. the large signals show up at the tree-level in both the curvature trispectrum and the tensor-curvature mixed bispectrum. | large spin-2 signals at the cosmological collider |
in this white paper, we present the megamapper concept. the megamapper is a proposed ground-based experiment to measure inflation parameters and dark energy from galaxy redshifts at $2<z<5$. in order to achieve path-breaking results with a mid-scale investment, the megamapper combines existing technologies for critical path elements and pushes innovative development in other design areas. to this aim, we envision a 6.5-m magellan-like telescope, with a newly designed wide field, coupled with desi spectrographs, and small-pitch robots to achieve multiplexing of at least 26,000. this will match the expected achievable target density in the redshift range of interest and provide a 10x capability over the existing state-of the art, without a 10x increase in project budget. | the megamapper: a stage-5 spectroscopic instrument concept for the study of inflation and dark energy |
quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. to date, only a few quasars have been reported at z> 6.5 (<800 myr after the big bang). in this work, we present six additional z≳ 6.5 quasars discovered using the pan-starrs1 survey. we use a sample of 15 z≳ 6.5 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. we report four main results: (1) the majority of z≳ 6.5 quasars show large blueshifts of the broad c iv λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3× higher than a quasar sample at z∼ 1; (2) we estimate the quasars’ black hole masses ({m}{bh} ∼ (0.3-5) × 109 m ⊙) via modeling of the mg ii λ2798 emission line and rest-frame uv continuum and find that quasars at high redshift accrete their material (with < ({l}{bol}/{l}{edd})> =0.39) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the fe ii/mg ii abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for z∼ 6 quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. finally, we present new millimeter observations of the [c ii] 158 μm emission line and underlying dust continuum from noema for four quasars and provide new accurate redshifts and [c ii]/infrared luminosity estimates. the analysis presented here shows the large range of properties of the most distant quasars. | physical properties of 15 quasars at z ≳ 6.5 |
we report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range 6.3 < z ≤ 7.64, including 32 quasars at z > 6.5, forming the largest quasar near-infrared spectral sample at this redshift. the spectra, taken with keck, gemini, vlt, and magellan, allow investigations of central black hole mass and quasar rest-frame ultraviolet spectral properties. the black hole masses derived from the mg ii emission lines are in the range (0.3-3.6) × 109 m ⊙, which requires massive seed black holes with masses ≳103-104 m ⊙, assuming eddington accretion since z = 30. the eddington ratio distribution peaks at λ edd ~ 0.8 and has a mean of 1.08, suggesting high accretion rates for these quasars. the c iv-mg ii emission-line velocity differences in our sample show an increase of c iv blueshift toward higher redshift, but the evolutionary trend observed from this sample is weaker than the previous results from smaller samples at similar redshift. the fe ii/mg ii flux ratios derived for these quasars up to z = 7.6, compared with previous measurements at different redshifts, do not show any evidence of strong redshift evolution, suggesting metal-enriched environments in these quasars. using this quasar sample, we create a quasar composite spectrum for z > 6.5 quasars and find no significant redshift evolution of quasar broad emission lines and continuum slope, except for a blueshift of the c iv line. our sample yields a strong broad absorption line quasar fraction of ~24%, higher than the fractions in lower-redshift quasar samples, although this could be affected by small sample statistics and selection effects. | probing early supermassive black hole growth and quasar evolution with near-infrared spectroscopy of 37 reionization-era quasars at 6.3 < z ≤ 7.64 |
we consider gravity mediated by non-metricity, with vanishing curvature and torsion. the gravitational action, including an arbitrary function of the non-metric scalar, is investigated in view of characterizing the dark energy effects. in particular, we present a method to reconstruct the f (q) action without resorting to a priori assumptions on the cosmological model. to this purpose, we adopt a method based on rational padé approximations, which provides a stable behaviour of the cosmographic series at high redshifts, alleviating the convergence issues proper of the standard approach. we thus describe how to reconstruct f (q) through a numerical inversion procedure based on the current observational bounds on cosmographic parameters. our analysis suggests that the best approximation for describing the accelerated expansion of the universe is represented by a scenario with f (q) = α + βqn. finally, possible deviations from the standard λcdm model are discussed. | model-independent reconstruction of f(q) non-metric gravity |
cosmological observations are used to test for imprints of an ultralight axionlike field (ula), with a range of potentials v (ϕ )∝[1 -cos (ϕ /f )]n set by the axion-field value ϕ and decay constant f . scalar field dynamics dictate that the field is initially frozen and then begins to oscillate around its minimum when the hubble parameter drops below some critical value. for n =1 , once dynamical, the axion energy density dilutes as matter; for n =2 it dilutes as radiation and for n =3 it dilutes faster than radiation. both the homogeneous evolution of the ula and the dynamics of its linear perturbations are included, using an effective fluid approximation generalized from the usual n =1 case. ula models are parametrized by the redshift zc when the field becomes dynamical, the fractional energy density fzc≡ωa(zc)/ωtot(zc) in the axion field at zc, and the effective sound speed cs2. using planck, bao and jla data, constraints on fzcare obtained. ulas are degenerate with dark energy for all three potentials if 1 +zc≲10 . when 3 ×104≳1 +zc≳10 , fz c is constrained to be ≲0.004 for n =1 and fzc≲0.02 for the other two potentials. the constraints then relax with increasing zc. these results have implications for ulas as a resolution to cosmological tensions, such as discrepant measurements of the hubble constant, or the edges measurement of the global 21 cm signal. | cosmological implications of ultralight axionlike fields |
the edelweiss collaboration has performed a search for dark matter particles with masses below the gev scale with a 33.4-g germanium cryogenic detector operated in a surface lab. the energy deposits were measured using a neutron-transmutation-doped ge thermal sensor with a 17.7 ev (rms) baseline heat energy resolution leading to a 60 ev analysis energy threshold. despite a moderate lead shielding and the high-background environment, the first sub-gev spin-independent dark matter limit based on a germanium target has been achieved. the experiment provides the most stringent, nuclear-recoil-based, above-ground limit on spin-independent interactions above 600 mev /c2 . the experiment also provides the most stringent limits on spin-dependent interactions with protons and neutrons below 1.3 gev /c2 . furthermore, the dark matter search results were studied in the context of strongly interacting massive particles, taking into account earth-shielding effects, for which new regions of the available parameter space have been excluded. finally, the dark matter search has also been extended to interactions via the migdal effect, resulting for the first time in the exclusion of particles with masses between 45 and 150 mev /c2 with spin-independent cross sections ranging from 10-29 to 10-26 cm2. | searching for low-mass dark matter particles with a massive ge bolometer operated above ground |
we study the production of primordial black hole (pbh) binaries and the resulting merger rate, accounting for an extended pbh mass function and the possibility of a clustered spatial distribution. under the hypothesis that the gravitational wave events observed by ligo were caused by pbh mergers, we show that it is possible to satisfy all present constraints on the pbh abundance, and find the viable parameter range for the lognormal pbh mass function. the non-observation of a gravitational wave background allows us to derive constraints on the fraction of dark matter in pbhs, which are stronger than any other current constraint in the pbh mass range 0.5-30msolar. we show that the predicted gravitational wave background can be observed by the coming runs of ligo, and its non-observation would indicate that the observed events are not of primordial origin. as the pbh mergers convert matter into radiation, they may have interesting cosmological implications, for example in the context of relieving the tension between high and low redshift measurements of the hubble constant. however, we find that these effects are suppressed as, after recombination, no more that 1% of dark matter can be converted into gravitational waves. | gravitational waves from primordial black hole mergers |
this paper presents an overview of the polarized sky as seen by planck hfi at 353 ghz, which is the most sensitive planck channel for dust polarization. we construct and analyse maps of dust polarization fraction and polarization angle at 1° resolution, taking into account noise bias and possible systematic effects. the sensitivity of the planck hfi polarization measurements allows for the first time a mapping of galactic dust polarized emission on large scales, including low column density regions. we find that the maximum observed dust polarization fraction is high (pmax = 19.8%), in particular in some regions of moderate hydrogen column density (nh < 2 × 1021 cm-2). the polarization fraction displays a large scatter at nh below a few 1021 cm-2. there is a general decrease in the dust polarization fraction with increasing column density above nh ≃ 1 × 1021 cm-2 and in particular a sharp drop above nh ≃ 1.5 × 1022 cm-2. we characterize the spatial structure of the polarization angle using the angle dispersion function. we find that the polarization angle is ordered over extended areas of several square degrees, separated by filamentary structures of high angle dispersion function. these appear as interfaces where the sky projection of the magnetic field changes abruptly without variations in the column density. the polarization fraction is found to be anti-correlated with the dispersion of polarization angles. these results suggest that, at the resolution of 1°, depolarization is due mainly to fluctuations in the magnetic field orientation along the line of sight, rather than to the loss of grain alignment in shielded regions. we also compare the polarization of thermal dust emission with that of synchrotron measured with planck, low-frequency radio data, and faraday rotation measurements toward extragalactic sources. these components bear resemblance along the galactic plane and in some regions such as the fan and north polar spur regions. the poor match observed in other regions shows, however, that dust, cosmic-ray electrons, and thermal electrons generally sample different parts of the line of sight. appendices are available in electronic form at http://www.aanda.org | planck intermediate results. xix. an overview of the polarized thermal emission from galactic dust |
within the standard three-neutrino framework, the absolute neutrino masses and their ordering (either normal, no, or inverted, io) are currently unknown. however, the combination of current data coming from oscillation experiments, neutrinoless double beta (0 ν β β ) decay searches, and cosmological surveys, can provide interesting constraints for such unknowns in the sub-ev mass range, down to o (10-1) ev in some cases. we discuss current limits on absolute neutrino mass observables by performing a global data analysis that includes the latest results from oscillation experiments, 0 ν β β decay bounds from the kamland-zen experiment, and constraints from representative combinations of planck measurements and other cosmological data sets. in general, no appears to be somewhat favored with respect to io at the level of ∼2 σ , mainly by neutrino oscillation data (especially atmospheric), corroborated by cosmological data in some cases. detailed constraints are obtained via the χ2 method, by expanding the parameter space either around separate minima in no and io or around the absolute minimum in any ordering. implications for upcoming oscillation and nonoscillation neutrino experiments, including β -decay searches, are also discussed. | global constraints on absolute neutrino masses and their ordering |
an important unsolved problem that affects practically all attempts to connect string theory to cosmology and phenomenology is how to distinguish effective field theories belonging to the string landscape from those that are not consistent with a quantum theory of gravity at high energies (the "string swampland"). it was recently proposed that potentials of the string landscape must satisfy at least two conditions, the "swampland criteria", that severely restrict the types of cosmological dynamics they can sustain. the first criterion states that the (multi-field) effective field theory description is only valid over a field displacement δ phi <= δ ~ script o(1) (in units where the planck mass is 1), measured as a distance in the target space geometry. a second, more recent, criterion asserts that, whenever the potential v is positive, its slope must be bounded from below, and suggests |∇ v| / v >= c ~ script o(1). a recent analysis concluded that these two conditions taken together practically rule out slow-roll models of inflation. in this note we show that the two conditions rule out inflationary backgrounds that follow geodesic trajectories in field space, but not those following curved, non-geodesic, trajectories (which are parametrized by a non-vanishing bending rate ω of the multi-field trajectory). we derive a universal lower bound on ω (relative to the hubble parameter h) as a function of δ, c and the number of efolds ne, assumed to be at least of order 60. if later studies confirm c and δ to be strictly script o(1), the bound implies strong turns with ω / h >= 3 ne ~ 180. slow-roll inflation in the landscape is not ruled out, but it is strongly multi-field. | the string swampland constraints require multi-field inflation |
we present the unwise catalog, containing the positions and fluxes of roughly 2 billion objects observed by the wide-field infrared survey explorer (wise) over the full sky. the unwise catalog has two advantages over the existing wise catalog (allwise): first, it is based on significantly deeper imaging, and second, it features improved modeling of crowded regions. the deeper imaging used in the unwise catalog comes from the coaddition of all publicly available 3-5 μm wise imaging, including that from the ongoing neowise-reactivation mission, thereby increasing the total exposure time by a factor of 5 relative to allwise. at these depths, even at high galactic latitudes, many sources are blended with their neighbors; accordingly, the unwise analysis simultaneously fits thousands of sources to obtain accurate photometry. our new catalog detects sources roughly 0.7 magnitudes fainter than the allwise catalog at 5σ, and more accurately models millions of faint sources in the galactic plane, enabling a wealth of galactic and extragalactic science. in particular, relative to allwise, unwise doubles the number of galaxies detected between redshifts 0 and 1 and triples the number between redshifts 1 and 2, cataloging more than half a billion galaxies over the whole sky. | the unwise catalog: two billion infrared sources from five years of wise imaging |
using a 10d lift of nonperturbative volume stabilization in type iib string theory, we study the limitations for obtaining de sitter vacua. based on this we find that the simplest kachru, kallosh, linde, and trivedi vacua with a single kähler modulus stabilized by a gaugino condensate cannot be uplifted to de sitter. rather, the uplift flattens out due to stronger backreaction on the volume modulus than has previously been anticipated, resulting in vacua which are metastable and supersymmetry breaking, but that are always anti-de sitter (ads). however, we also show that setups such as racetrack stabilization can avoid this issue. in these models it is possible to obtain supersymmetric ads vacua with a cosmological constant that can be tuned to zero while retaining finite moduli stabilization. in this regime, it seems that de sitter uplifts are possible with negligible backreaction on the internal volume. we exhibit this behavior also from the 10d perspective. | toward de sitter space from ten dimensions |
we consider single-field inflation in light of string-motivated ‘swampland’ conjectures suggesting that effective scalar field theories with a consistent uv completion must have field excursion , in combination with a sufficiently steep potential, . here, we show that the swampland conjectures are inconsistent with existing observational constraints on single-field inflation. focusing on the observationally favoured class of concave potentials, we map the allowed swampland region onto the ns -r ‘zoo plot’ of inflationary models, and find that consistency with the planck satellite and bicep2/keck array requires and , in strong tension with swampland conjectures. extension to non-canonical models such as dbi inflation does not significantly weaken the bound. | the zoo plot meets the swampland: mutual (in)consistency of single-field inflation, string conjectures, and cosmological data |
we present a set of tools to assess the capabilities of lisa to detect and reconstruct the spectral shape and amplitude of a stochastic gravitational wave background (sgwb) . we first provide the lisa power-law sensitivity curve and binned power-law sensitivity curves, based on the latest updates on the lisa design. these curves are useful to make a qualitative assessment of the detection and reconstruction prospects of a sgwb . for a quantitative reconstruction of a sgwb with arbitrary power spectrum shape, we propose a novel data analysis technique: by means of an automatized adaptive procedure, we conveniently split the lisa sensitivity band into frequency bins, and fit the data inside each bin with a power law signal plus a model of the instrumental noise. we apply the procedure to sgwb signals with a variety of representative frequency profiles, and prove that lisa can reconstruct their spectral shape. our procedure, implemented in the code sgwbinner, is suitable for homogeneous and isotropic sgwbs detectable at lisa, and it is also expected to work for other gw observatories. | reconstructing the spectral shape of a stochastic gravitational wave background with lisa |
this white paper envisions a revolutionary post-desi, post-lsst dark energy program based on intensity mapping of the redshifted 21cm emission line from neutral hydrogen at radio frequencies. the proposed intensity mapping survey has the unique capability to quadruple the volume of the universe surveyed by optical programs, provide a percent-level measurement of the expansion history to $z \sim 6$, open a window to explore physics beyond the concordance $\lambda$cdm model, and to significantly improve the precision on standard cosmological parameters. in addition, characterization of dark energy and new physics will be powerfully enhanced by cross-correlations with optical surveys and cosmic microwave background measurements. the rich dataset obtained by the proposed intensity mapping instrument will be simultaneously useful in exploring the time-domain physics of fast radio transients and pulsars, potentially in live "multi-messenger" coincidence with other observatories. the core dark energy/inflation science advances enabled by this program are the following: (i) measure the expansion history of the universe over $z=0.3-6$ with a single instrument, extending the range deep into the pre-acceleration era, providing an unexplored window for new physics; (ii) measure the growth rate of structure in the universe over the same redshift range; (iii) observe, or constrain, the presence of inflationary relics in the primordial power spectrum, improving existing constraints by an order of magnitude; (iv) observe, or constrain, primordial non-gaussianity with unprecedented precision, improving constraints on several key numbers by an order of magnitude. detailed mapping of the enormous, and still largely unexplored, volume of cosmic space will thus provide unprecedented information on fundamental questions of the vacuum energy and early-universe physics. | inflation and early dark energy with a stage ii hydrogen intensity mapping experiment |
we introduce darkbit, an advanced software code for computing dark matter constraints on various extensions to the standard model of particle physics, comprising both new native code and interfaces to external packages. this release includes a dedicated signal yield calculator for gamma-ray observations, which significantly extends current tools by implementing a cascade-decay monte carlo, as well as a dedicated likelihood calculator for current and future experiments ( gamlike). this provides a general solution for studying complex particle physics models that predict dark matter annihilation to a multitude of final states. we also supply a direct detection package that models a large range of direct detection experiments ( ddcalc), and that provides the corresponding likelihoods for arbitrary combinations of spin-independent and spin-dependent scattering processes. finally, we provide custom relic density routines along with interfaces to darksusy, micromegas, and the neutrino telescope likelihood package nulike. darkbit is written in the framework of the global and modular beyond the standard model inference tool ( gambit), providing seamless integration into a comprehensive statistical fitting framework that allows users to explore new models with both particle and astrophysics constraints, and a consistent treatment of systematic uncertainties. in this paper we describe its main functionality, provide a guide to getting started quickly, and show illustrative examples for results obtained with darkbit (both as a stand-alone tool and as a gambit module). this includes a quantitative comparison between two of the main dark matter codes ( darksusy and micromegas), and application of darkbit 's advanced direct and indirect detection routines to a simple effective dark matter model. | darkbit: a gambit module for computing dark matter observables and likelihoods |
we consider the production of matter and radiation during reheating after inflation, restricting our attention solely to gravitational interactions. processes considered are the exchange of a graviton, hμ ν , involved in the scattering of the inflaton or particles in the newly created radiation bath. in particular, we consider the gravitational production of dark matter (scalar or fermionic) from the thermal bath as well as from scattering of the inflaton condensate. we also consider the gravitational production of radiation from inflaton scattering. in the latter case, we also derive a lower bound on the maximal temperature of order of 1012 gev for a typical α -attractor scenario from ϕ ϕ →hμ ν→ standard model fields (dominated by the production of higgs bosons). this lower gravitational bound becomes the effective maximal temperature for reheating temperatures, trh≲109 gev . the processes we consider are all minimal in the sense that they are present in any nonminimal extension of the standard model theory based on einstein gravity and cannot be neglected. we compare each of these processes to determine their relative importance in the production of both radiation and dark matter. | gravitational portals in the early universe |
we analyze phase transitions in the minimal extension of the sm with a real singlet scalar field. the novelty of our study is that we identify and analyze in detail the region of parameter space where the first order phase transition can occur and in particular when the bubbles with true vacuum can reach relativistic velocities. this region is interesting since it can lead to the new recently discussed baryogenesis and dark matter production mechanisms. we fully analyze different models for the production of dark matter and baryogenesis as well as the possibilities of discovery at the current and future experiments. | ultra-relativistic bubbles from the simplest higgs portal and their cosmological consequences |
we study direct detection bounds on cosmic ray-upscattered dark matter in simplified models including light mediators. we find that the energy dependence in the scattering cross section is significant, and produces stronger bounds than previously found (which assumed constant cross sections) by many orders of magnitude at low dark matter mass. finally, we compute the "neutrino-floor" that will limit future direct detection searches for cosmic ray-upscattered dark matter. while we focus on vector interactions for illustration, we emphasize that the energy dependence is critical in determining accurate bounds on any particle physics model of dark matter-cosmic ray interactions from experimental data on this scenario. | bounds on cosmic ray-boosted dark matter in simplified models and its corresponding neutrino-floor |
despite solid theoretical and observational grounds for the pairing of supermassive black holes (smbhs) after galaxy mergers, definitive evidence for the existence of close (sub-parsec) separation smbh binaries (smbhbs) approaching merger is yet to be found. this chapter reviews techniques aimed at discovering such smbhbs in galactic nuclei. we motivate the search with a brief overview of smbhb formation and evolution, and the gaps in our present-day theoretical understanding. we then present existing observational evidence for smbhbs and discuss ongoing efforts to provide definitive evidence for a population at sub-parsec orbital separations, where many of the aforementioned theoretical gaps lie. we conclude with future prospects for discovery with electromagnetic (primarily time-domain) surveys, high-resolution imaging experiments, and low-frequency gravitational-wave detectors. | observational signatures of supermassive black hole binaries |
we constrain six possible extensions to the λ cold dark matter (cdm) model using measurements from the dark energy survey's first three years of observations, alone and in combination with external cosmological probes. the des data are the two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. we use simulated data vectors and blind analyses of real data to validate the robustness of our results to astrophysical and modeling systematic errors. in many cases, constraining power is limited by the absence of theoretical predictions beyond the linear regime that are reliable at our required precision. the λ cdm extensions are dark energy with a time-dependent equation of state, nonzero spatial curvature, additional relativistic degrees of freedom, sterile neutrinos with ev-scale mass, modifications of gravitational physics, and a binned σ8(z ) model which serves as a phenomenological probe of structure growth. for the time-varying dark energy equation of state evaluated at the pivot redshift we find (wp,wa)=(-0.9 9-0.17+0.28,-0.9 ±1.2 ) at 68% confidence with zp=0.24 from the des measurements alone, and (wp,wa)=(-1.0 3-0.03+0.04,-0. 4-0.3+0.4) with zp=0.21 for the combination of all data considered. curvature constraints of ωk=0.0009 ±0.0017 and effective relativistic species neff=3.1 0-0.16+0.15 are dominated by external data, though adding des information to external low-redshift probes tightens the ωk constraints that can be made without cosmic microwave background observables by 20%. for massive sterile neutrinos, des combined with external data improves the upper bound on the mass meff by a factor of 3 compared to previous analyses, giving 95% limits of (δ neff,meff)≤(0.28 ,0.20 ev ) when using priors matching a comparable planck analysis. for modified gravity, we constrain changes to the lensing and poisson equations controlled by functions σ (k ,z )=σ0ωλ(z )/ωλ ,0 and μ (k ,z )=μ0ωλ(z )/ωλ ,0, respectively, to σ0=0. 6-0.5+0.4 from des alone and (σ0,μ0)=(0.04 ±0.05 ,0.0 8-0.19+0.21) for the combination of all data, both at 68% confidence. overall, we find no significant evidence for physics beyond λ cdm . | dark energy survey year 3 results: constraints on extensions to λ cdm with weak lensing and galaxy clustering |
the standard cosmological model predicts statistically isotropic cosmic microwave background (cmb) fluctuations. however, several summary statistics of cmb isotropy have anomalous values, including: the low level of large-angle temperature correlations, $s_{1/2}$; the excess power in odd versus even low-$\ell$ multipoles, $r^{tt}$; the (low) variance of large-scale temperature anisotropies in the ecliptic north, but not the south, $\sigma^2_{16}$; and the alignment and planarity of the quadrupole and octopole of temperature, $s_{qo}$. individually, their low $p$-values are weak evidence for violation of statistical isotropy. the correlations of the tail values of these statistics have not to this point been studied. we show that the joint probability of all four of these happening by chance in $\lambda$cdm is likely $\leq3\times10^{-8}$. this constitutes more than $5\sigma$ evidence for violation of statistical isotropy. | the universe is not statistically isotropic |
we present an overview of the design and status of the polarbear-2 and the simons array experiments. polarbear-2 is a cosmic microwave background polarimetry experiment which aims to characterize the arc-minute angular scale b-mode signal from weak gravitational lensing and search for the degree angular scale b-mode signal from inflationary gravitational waves. the receiver has a 365 mm diameter focal plane cooled to 270 mk. the focal plane is filled with 7588 dichroic lenslet-antenna-coupled polarization sensitive transition edge sensor (tes) bolometric pixels that are sensitive to 95 and 150 ghz bands simultaneously. the tes bolometers are read-out by squids with 40 channel frequency domain multiplexing. refractive optical elements are made with high-purity alumina to achieve high optical throughput. the receiver is designed to achieve noise equivalent temperature of 5.8 \upmu k_cmb√{s} in each frequency band. polarbear-2 will deploy in 2016 in the atacama desert in chile. the simons array is a project to further increase sensitivity by deploying three polarbear-2 type receivers. the simons array will cover 95, 150, and 220 ghz frequency bands for foreground control. the simons array will be able to constrain tensor-to-scalar ratio and sum of neutrino masses to σ (r) = 6× 10^{-3} at r = 0.1 and sum m_{\upnu } (σ =1) to 40 mev. | the polarbear-2 and the simons array experiments |
the standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. it is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. the einstein telescope is expected to produce 104-105 gravitational wave detections per year, 50-100 of which will be lensed. here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. we demonstrate that just 10 such systems can provide a hubble constant uncertainty of 0.68% for a flat lambda cold dark matter universe in the era of third-generation ground-based detectors. | precision cosmology from future lensed gravitational wave and electromagnetic signals |
the recently obtained hairy kerr black holes, due to additional sources or surrounding fluid, like dark matter, with conserved energy-momentum tensor, have a deviation α and primary hair l0, apart from rotation parameter a and mass m. in the wake of the event horizon telescope (eht) observations of the supermassive black hole m87*, a recent surge in interest in black hole shadows suggests comparing the black holes in general relativity and modified theories of gravity to assess these models' differences. motivated by this, we take on an extensive study of the rotating hairy kerr black holes, which encompasses, in particular cases, the kerr black hole (α = 0). we investigate ergosphere and shadows of the black holes to infer that their size and shape are affected due to the l0 and are found to harbour a richer chaotic structure. in particular, the hairy kerr black holes possess smaller size but more distorted shadows when compared with kerr black holes. we also estimate the parameters l0 and a associated with hairy kerr black holes using the shadow observables. the inferred circularity deviation δc ≤ 0.1 for the m87* black hole is satisfied, whereas shadow angular diameter θd = 42 ± 3μas, within 1σ region, for a given choice of α, places bounds on the parameters a and l0. interestingly, the shadow axial ratio obeying 1 < dx ≲ 4/3 is in agreement with the eht results and thus eventuates in the hairy kerr black holes being suitable candidates for astrophysical black holes. | parameter estimation of hairy kerr black holes from its shadow and constraints from m87* |
we present and characterize the galaxy shape catalogue from the first 3 yr of dark energy survey (des) observations, over an effective area of 4143 deg2 of the southern sky. we describe our data analysis process and our self-calibrating shear measurement pipeline metacalibration, which builds and improves upon the pipeline used in the des year 1 analysis in several aspects. the des year 3 weak-lensing shape catalogue consists of 100 204 026 galaxies, measured in the riz bands, resulting in a weighted source number density of neff = 5.59 gal arcmin-2 and corresponding shape noise σe = 0.261. we perform a battery of internal null tests on the catalogue, including tests on systematics related to the point spread function (psf) modelling, spurious catalogue b-mode signals, catalogue contamination, and galaxy properties. | dark energy survey year 3 results: weak lensing shape catalogue |
in this paper, we discuss the possible effects of dark matter on a schwarzschild black hole with the correction of extended uncertainty principle (eup), such as the parameter α and the large fundamental length scale l∗. in particular, we surround the eup black hole of mass m with a static spherical shell of dark matter described by the parameters mass m, inner radius rs, and thickness δrs . in this study, we find that there is no deviation in the event horizon, which readily implies that the black hole temperature due to the hawking radiation is independent of any dark matter concentration. in addition, we show some effects of the eup parameter on the innermost stable circular orbit (isco) radius of time-like particles, photon sphere, shadow radius, and weak deflection angle. it is found that time-like orbits are affected by deviation of low values of mass m. a greater dark matter density is needed to have remarkable effects on the null orbits. using the analytic expression for the shadow radius and the approximation δrs > >rs , it is revealed that l∗ should not be lower than 2 m . to broaden the scope of this study, we also calculate the analytic expression for the weak deflection angle using the ishihara et al. method (ishihara et al., 2016). as a result, we show that δrs is improved by a factor of (1 + 4 αm2 / l∗2) due to the eup correction parameters. the calculated shadow radius and weak deflection angle are then compared using the estimated values of the galactic mass from sgr a*, m87, and ugc 7232, as well as the mass of the supermassive black hole at their center. | shadow and weak deflection angle of extended uncertainty principle black hole surrounded with dark matter |
we constrain effective field theories by going beyond the familiar positivity bounds that follow from unitarity, analyticity, and crossing symmetry of the scattering amplitudes. as interesting examples, we discuss the implications of the bounds for the galileon and ghost-free massive gravity. the combination of our theoretical bounds with the experimental constraints on the graviton mass implies that the latter is either ruled out or unable to describe gravitational phenomena, let alone to consistently implement the vainshtein mechanism, down to the relevant scales of fifth-force experiments, where general relativity has been successfully tested. we also show that the galileon theory must contain symmetry-breaking terms that are at most one-loop suppressed compared to the symmetry-preserving ones. we comment as well on other interesting applications of our bounds. | beyond positivity bounds and the fate of massive gravity |
we present the vla-cosmos 3 ghz large project based on 384 h of observations with the karl g. jansky very large array (vla) at 3 ghz (10 cm) toward the two square degree cosmic evolution survey (cosmos) field. the final mosaic reaches a median rms of 2.3 μjy beam-1 over the two square degrees at an angular resolution of 0.75″. to fully account for the spectral shape and resolution variations across the broad (2 ghz) band, we image all data with a multiscale, multifrequency synthesis algorithm. we present a catalog of 10 830 radio sources down to 5σ, out of which 67 are combined from multiple components.comparing the positions of our 3 ghz sources with those from the very long baseline array (vlba)-cosmos survey, we estimate that the astrometry is accurate to 0.01″ at the bright end (signal-to-noise ratio, s/n3 ghz > 20). survival analysis on our data combined with the vla-cosmos 1.4 ghz joint project catalog yields an expected median radio spectral index of α = -0.7. we compute completeness corrections via monte carlo simulations to derive the corrected 3 ghz source counts. our counts are in agreement with previously derived 3 ghz counts based on single-pointing (0.087 square degrees) vla data. in summary, the vla-cosmos 3 ghz large project simultaneously provides the largest and deepest radio continuum survey at high (0.75″) angular resolution to date, bridging the gap between last-generation and next-generation surveys. the 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/602/a1 | the vla-cosmos 3 ghz large project: continuum data and source catalog release |
this report summarises progress made in estimating the local density of dark matter (ρdm,⊙), a quantity that is especially important for dark matter direct detection experiments. we outline and compare the most common methods to estimate ρdm,⊙ and the results from recent studies, including those that have benefited from the observations of the esa/gaia satellite. the result of most local analyses coincide within a range of ${\rho }_{\mathrm{d}\mathrm{m},\odot }\simeq 0.4\text{--}0.6\enspace \mathrm{g}\mathrm{e}\mathrm{v}\enspace \mathrm{c}{\mathrm{m}}^{-3}=0.011\text{--}0.016\enspace {m}_{\odot }/\mathrm{p}{\mathrm{c}}^{3}$, while a slightly lower range of ${\rho }_{\mathrm{d}\mathrm{m},\odot }\simeq 0.3\text{--}0.5\enspace \mathrm{g}\mathrm{e}\mathrm{v}\enspace \mathrm{c}{\mathrm{m}}^{-3}=0.008\text{--}0.013\enspace {m}_{\odot }/\mathrm{p}{\mathrm{c}}^{3}$ is preferred by most global studies. in light of recent discoveries, we discuss the importance of going beyond the approximations of what we define as the ideal galaxy (a steady-state galaxy with axisymmetric shape and a mirror symmetry across the mid-plane) in order to improve the precision of ρdm,⊙ measurements. in particular, we review the growing evidence for local disequilibrium and broken symmetries in the present configuration of the milky way, as well as uncertainties associated with the galactic distribution of baryons. finally, we comment on new ideas that have been proposed to further constrain the value of ρdm,⊙, most of which would benefit from gaia's final data release. | dark matter local density determination: recent observations and future prospects |
femtolensing of gamma ray bursts (grbs) has been put forward as an exciting possibility to probe exotic astrophysical objects with masses below 10-13 solar masses such as small primordial black holes or ultra-compact dark matter minihalos, made up for instance of qcd axions. in this paper we critically review this idea, properly taking into account the extended nature of the source as well as wave optics effects. we demonstrate that most grbs are inappropriate for femtolensing searches due to their large sizes. this removes the previous femtolensing bounds on primordial black holes, implying that vast regions of parameter space for primordial black hole dark matter are not robustly constrained. still, we entertain the possibility that a small fraction of grbs, characterized by fast variability can have smaller sizes and be useful. however, a large number of such bursts would need to be observed to achieve meaningful constraints. we study the sensitivity of future observations as a function of the number of detected grbs and of the size of the emission region. | femtolensing by dark matter revisited |
we present a comprehensive analysis of the evolution of the morphological and structural properties of a large sample of galaxies at z = 3-9 using early james webb space telescope (jwst) ceers nircam observations. our sample consists of 850 galaxies at z > 3 detected in both hubble space telescope (hst)/wfc3 and ceers jwst/nircam images, enabling a comparison of hst and jwst morphologies. we conduct a set of visual classifications, with each galaxy in the sample classified three times. we also measure quantitative morphologies across all nircam filters. we find that galaxies at z > 3 have a wide diversity of morphologies. galaxies with disks make up 60% of galaxies at z = 3, and this fraction drops to ~30% at z = 6-9, while galaxies with spheroids make up ~30%-40% across the redshift range, and pure spheroids with no evidence for disks or irregular features make up ~20%. the fraction of galaxies with irregular features is roughly constant at all redshifts (~40%-50%), while those that are purely irregular increases from ~12% to ~20% at z > 4.5. we note that these are apparent fractions, as many observational effects impact the visibility of morphological features at high redshift. on average, spheroid-only galaxies have a higher sérsic index, smaller size, and higher axis ratio than disk or irregular galaxies. across all redshifts, smaller spheroid and disk galaxies tend to be rounder. overall, these trends suggest that galaxies with established disks and spheroids exist across the full redshift range of this study, and further work with large samples at higher redshift is needed to quantify when these features first formed. | ceers key paper. iii. the diversity of galaxy structure and morphology at z = 3-9 with jwst |
composed of ultralight bosons, fuzzy dark matter provides an intriguing solution to challenges that the standard cold dark matter model encounters on subgalactic scales. the ultralight dark matter with mass m ∼10-23 ev will induce a periodic oscillation in gravitational potentials with a frequency in the nanohertz band, leading to observable effects in the arrival times of radio pulses from pulsars. unlike scalar dark matter, pulsar timing signals induced by the vector dark matter are dependent on the oscillation direction of the vector fields. in this work, we search for ultralight vector dark matter in the mass range of [2 ×10-24,2 ×10-22] ev through its gravitational effect in the parkes pulsar timing array (ppta) second data release. since no statistically significant detection is made, we place 95% upper limits on the local dark matter density as ρvf≲5 gev/cm 3 for m ≲10-23 ev . as no preferred direction is found for the vector dark matter, these constraints are comparable to those given by the scalar dark matter search with an earlier 12-year dataset of ppta. | constraining ultralight vector dark matter with the parkes pulsar timing array second data release |
we analyze the phase transition in improved holographic qcd to obtain an estimate of the gravitational wave signal emitted in the confinement transition of a pure su(3) yang-mills dark sector. we derive the effective action from holography and show that the energy budget and duration of the phase transition can be calculated with minor errors. these are used as input to obtain a prediction of the gravitational wave signal. to our knowledge, this is the first computation of the gravitational wave signal in a holographic model designated to match lattice data on the thermal properties of pure yang-mills. | gravitational waves from dark su(3) yang-mills theory |
the edges collaboration has recently reported the detection of a stronger-than-expected absorption feature in the global 21-cm spectrum, centered at a frequency corresponding to a redshift of z ≃17 . this observation has been interpreted as evidence that the gas was cooled during this era as a result of scattering with dark matter. in this letter, we explore this possibility, applying constraints from the cosmic microwave background, light element abundances, supernova 1987a, and a variety of laboratory experiments. after taking these constraints into account, we find that the vast majority of the parameter space capable of generating the observed 21-cm signal is ruled out. the only viable models are those in which a small fraction, ∼0.3 %- 2 % , of the dark matter consists of particles with a mass of ∼10 - 80 mev and which couple to the photon through a small electric charge, roughly 10-6- 10-4 as large as the electron charge. furthermore, in order to avoid being overproduced in the early universe, such models must be supplemented with an additional depletion mechanism, such as annihilations through a lμ-lτ gauge boson or annihilations to a pair of rapidly decaying hidden sector scalars. | severely constraining dark-matter interpretations of the 21-cm anomaly |
we report the results from a haloscope search for axion dark matter in the $3.3\text{-}4.2~{\mu}$ev mass range. this search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible" axion dark matter, the ksvz model. this sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise josephson parametric amplifier, and sub-kelvin temperatures. the validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals. | search for "invisible" axion dark matter in the $3.3\\text{-}4.2~{\\mu}$ev mass range |
there has recently been renewed interest in the possibility that the dark matter in the universe consists of primordial black holes (pbhs). current observational constraints leave only a few pbh mass ranges for this possibility. one of them is around 10-12 m⊙ . if pbhs with this mass are formed due to an enhanced scalar-perturbation amplitude, their formation is inevitably accompanied by the generation of gravitational waves (gws) with frequency peaked in the mhz range, precisely around the maximum sensitivity of the lisa mission. we show that, if these primordial black holes are the dark matter, lisa will be able to detect the associated gw power spectrum. although the gw source signal is intrinsically non-gaussian, the signal measured by lisa is a sum of the signal from a large number of independent sources suppressing the non-gaussianity at detection to an unobservable level. we also discuss the effect of the gw propagation in the perturbed universe. pbh dark matter generically leads to a detectable, purely isotropic, gaussian and unpolarized gw signal, a prediction that is testable with lisa. | primordial black hole dark matter: lisa serendipity |
the λ cold dark matter model (λcdm) represents the current standard model in cosmology. within this, there is a tension between the value of the hubble constant, h0, inferred from local distance indicators and the angular scale of fluctuations in the cosmic microwave background (cmb). in terms of bayseian evidence, we investigate whether the tension is significant enough to warrant new physics in the form of modifying or adding energy components to the standard cosmological model. we find that late time dark energy explanations are not favoured by data whereas a pre-cmb decoupling extra dark energy component has a positive, although not substantial, bayesian evidence. a constant equation of state of the additional early energy density is constrained to 0.086+0.04-0.03. although this value deviates significantly from 1/3, valid for dark radiation, the latter is favoured based on the bayesian evidence. if the tension persists, future estimates of h0 at the 1% level will be able to decisively determine which of the proposed explanations is favoured. | does the hubble constant tension call for new physics? |
in canonical single-field inflation, the production of primordial black holes (pbh) requires a transient violation of the slow-roll condition. the transient ultra slow-roll inflation is an example of such scenarios, and more generally, one can consider the transient constant-roll inflation. we investigate the squeezed bispectrum in the transient constant-roll inflation and find that maldacena's consistency relation holds for a sufficiently long-wavelength mode, whereas it is violated for modes around the peak scale for the non-attractor case. we also demonstrate how the one-loop corrections are modified compared to the case of the transient ultra slow-roll inflation, focusing on representative one-loop terms originating from a time derivative of the second slow-roll parameter in the cubic action. we find that the perturbativity requirement on those terms does not rule out the production of pbh from the transient constant-roll inflation. therefore, it is a simple counterexample of the recently claimed no-go theorem of pbh production from single-field inflation. | squeezed bispectrum and one-loop corrections in transient constant-roll inflation |
polarization of the cosmic microwave background (cmb) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar "axionlike" field. such a field may be responsible for early dark energy (ede), which is active prior to recombination and provides a solution to the so-called hubble tension. the ede field coupled to photons in a parity-violating manner would rotate the plane of linear polarization of the cmb and produce a cross-correlation power spectrum of e - and b -mode polarization fields with opposite parities. in this letter, we fit the e b power spectrum predicted by the photon-axion coupling of the ede model with a potential v (ϕ )∝[1 -cos (ϕ /f )]3 to polarization data from planck. we find that the unique shape of the predicted e b power spectrum is not favored by the data and obtain a first constraint on the photon-axion coupling constant, g =(0.04 ±0.16 )mpl-1 (68% c.l.), for the ede model that best fits the cmb and galaxy clustering data. this constraint is independent of the miscalibration of polarization angles of the instrument or the polarized galactic foreground emission. our limit on g may have important implications for embedding ede in fundamental physics, such as string theory. | constraints on early dark energy from isotropic cosmic birefringence |
the hubble tension between the λcdm-model-dependent prediction of the current expansion rate h0 using planck data and direct, model-independent measurements in the local universe from the sh0es collaboration disagree at >3.5σ. moreover, there exists a milder ~ 2σ tension between similar predictions for the amplitude s8 of matter fluctuations and its measurement in the local universe. as explanations relying on unresolved systematics have not been found, theorists have been exploring explanations for these anomalies that modify the cosmological model, altering early-universe-based predictions for these parameters. however, new cosmological models that attempt to resolve one tension often worsen the other. in this paper, we investigate a decaying dark matter (ddm) model as a solution to both tensions simultaneously. here, a fraction of dark matter density decays into dark radiation. the decay rate γ is proportional to the hubble rate h through the constant αdr, the only additional parameter of this model. then, this model deviates most from λcdm in the early universe, with αdr being positively correlated with h0 and negatively with s8. hence, increasing αdr (and allowing dark matter to decay in this way) can then diminish both tensions simultaneously. when only considering planck cmb data and the local sh0es prior on h0, ~ 1% dark matter decays, decreasing the s8 tension to 0.3σ and increasing the best-fit h0 by 1.6 km/s/mpc. however, the addition of intermediate-redshift data (the jla supernova dataset and baryon acoustic oscillation data) weakens the effectiveness of this model. only ~ 0.5% of the dark matter decays bringing the s8 tension back up to ~ 1.5 σ and the increase in the best-fit h0 down to 0.4 km/s/mpc. | alleviating the h0 and σ8 anomalies with a decaying dark matter model |
liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. the darkside-50 dark matter search here reports the first wimp search results obtained using a target of low-radioactivity argon. darkside-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the laboratori nazionali del gran sasso. the underground argon is shown to contain 39ar at a level reduced by a factor (1.4 ±0.2 )×103 relative to atmospheric argon. we report a background-free null result from (2616 ±43 ) kg d of data, accumulated over 70.9 live days. when combined with our previous search using an atmospheric argon, the 90% c.l. upper limit on the wimp-nucleon spin-independent cross section, based on zero events found in the wimp search regions, is 2.0 ×10-44 cm2 (8.6 ×10-44 cm2 , 8.0 ×10-43 cm2 ) for a wimp mass of 100 gev /c2 (1 tev /c2 , 10 tev /c2 ). | results from the first use of low radioactivity argon in a dark matter search |
determining the distribution of redshifts of galaxies observed by wide-field photometric experiments like the dark energy survey (des) is an essential component to mapping the matter density field with gravitational lensing. in this work we describe the methods used to assign individual weak lensing source galaxies from the des year 3 weak lensing source catalogue to four tomographic bins and to estimate the redshift distributions in these bins. as the first application of these methods to data, we validate that the assumptions made apply to the des y3 weak lensing source galaxies and develop a full treatment of systematic uncertainties. our method consists of combining information from three independent likelihood functions: self-organizing map p(z) (sompz), a method for constraining redshifts from galaxy photometry; clustering redshifts (wz), constraints on redshifts from cross-correlations of galaxy density functions; and shear ratios (srs), which provide constraints on redshifts from the ratios of the galaxy-shear correlation functions at small scales. finally, we describe how these independent probes are combined to yield an ensemble of redshift distributions encapsulating our full uncertainty. we calibrate redshifts with combined effective uncertainties of σ⟨z⟩ ~ 0.01 on the mean redshift in each tomographic bin. | dark energy survey year 3 results: redshift calibration of the weak lensing source galaxies |
early dark energy (ede) offers a particularly interesting theoretical approach to the hubble tension, albeit one that introduces its own set of challenges, including a new "why then" problem related to the ede injection time at matter-radiation equality, and a mild worsening of the large-scale structure (lss) tension. both these challenges center on the properties of dark matter, which becomes the dominant component of the universe at ede injection and is also responsible for seeding lss. motivated by this, we present the potential of couplings between ede and dark matter to address these challenges, focusing on a mechanism similar to chameleon dark energy theories, deeming this chameleon early dark energy (cede). we present relevant background and perturbation equations and study the dynamics of the case of a quartic scalar potential and an exponential coupling. | chameleon early dark energy and the hubble tension |
we present an optimized variant of the halo model, designed to produce accurate matter power spectra well into the non-linear regime for a wide range of cosmological models. to do this, we introduce physically motivated free parameters into the halo-model formalism and fit these to data from high-resolution n-body simulations. for a variety of λ cold dark matter (λcdm) and wcdm models, the halo-model power is accurate to ≃ 5 per cent for k ≤ 10h mpc-1 and z ≤ 2. an advantage of our new halo model is that it can be adapted to account for the effects of baryonic feedback on the power spectrum. we demonstrate this by fitting the halo model to power spectra from the owls (overwhelmingly large simulations) hydrodynamical simulation suite via parameters that govern halo internal structure. we are able to fit all feedback models investigated at the 5 per cent level using only two free parameters, and we place limits on the range of these halo parameters for feedback models investigated by the owls simulations. accurate predictions to high k are vital for weak-lensing surveys, and these halo parameters could be considered nuisance parameters to marginalize over in future analyses to mitigate uncertainty regarding the details of feedback. finally, we investigate how lensing observables predicted by our model compare to those from simulations and from halofit for a range of k-cuts and feedback models and quantify the angular scales at which these effects become important. code to calculate power spectra from the model presented in this paper can be found at https://github.com/alexander-mead/hmcode. | an accurate halo model for fitting non-linear cosmological power spectra and baryonic feedback models |
we present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 jwst fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of ~145 arcmin2. we homogeneously reduce the new jwst data and combine them with existing observations from the hubble space telescope. we select a robust sample of ~80 candidate quiescent and quenching galaxies at 3 < z < 5 using two methods: (1) based on their rest-frame uvj colors, and (2) a novel quantitative approach based on gaussian mixture modeling of the near-uv - u, u - v, and v - j rest-frame color space, which is more sensitive to recently quenched objects. we measure comoving number densities of massive (m ⋆ ≥ 1010.6 m ⊙) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. however, we find significant field-to-field variations of the number densities up to a factor of 2-3, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at z > 3, as could be expected for highly clustered massive systems. importantly, jwst enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. all data products, including the literature compilation, are made publicly available. | an atlas of color-selected quiescent galaxies at z > 3 in public jwst fields |
we present a public catalog of transients from the zwicky transient facility (ztf) bright transient survey, a magnitude-limited (m < 19 mag in either the g or r filter) survey for extragalactic transients in the ztf public stream. we introduce cuts on survey coverage, sky visibility around peak light, and other properties unconnected to the nature of the transient, and show that the resulting statistical sample is spectroscopically 97% complete at <18 mag, 93% complete at <18.5 mag, and 75% complete at <19 mag. we summarize the fundamental properties of this population, identifying distinct duration-luminosity correlations in a variety of supernova (sn) classes and associating the majority of fast optical transients with well-established spectroscopic sn types (primarily sn ibn and ii/iib). we measure the type ia sn and core-collapse (cc) sn rates and luminosity functions, which show good consistency with recent work. about 7% of cc sne explode in very low-luminosity galaxies (mi > -16 mag), 10% in red-sequence galaxies, and 1% in massive ellipticals. we find no significant difference in the luminosity or color distributions between the host galaxies of sne type ii and sne type ib/c, suggesting that line-driven wind stripping does not play a major role in the loss of the hydrogen envelope from their progenitors. future large-scale classification efforts with ztf and other wide-area surveys will provide high-quality measurements of the rates, properties, and environments of all known types of optical transients and limits on the existence of theoretically predicted but as yet unobserved explosions. * an interactive catalog with all data used in this paper is available at https://sites.astro.caltech.edu/ztf/bts and is updated in real time. | the zwicky transient facility bright transient survey. ii. a public statistical sample for exploring supernova demographics |
perturbation theory alone fails to describe thermodynamics of the electroweak phase transition. we review a technique combining perturbative and non-perturbative methods to overcome this challenge. accordingly, the principal theme is a tutorial of hightemperature dimensional reduction. we present an explicit derivation with a real singlet scalar and compute the thermal effective potential at two-loop order. in particular, we detail the dimensional reduction for a real-singlet extended standard model. the resulting effective theory will impact future non-perturbative studies based on lattice simulations as well as purely perturbative investigations. | robust approach to thermal resummation: standard model meets a singlet |
we present a systematic analysis of the x-ray emission of a sample of 17 optically selected, x-ray-detected tidal disruption events (tdes) discovered between 2014 and 2021. the x-ray light curves show a diverse range of temporal behaviors, with most sources not following the expected power-law decline. the x-ray spectra are mostly extremely soft and consistent with thermal emission from the inner region of an accretion disk that cools as the accretion rate decreases. three sources show the formation of a hard x-ray corona around 200 days after the uv/optical peak. the shape of the spectral energy distribution, traced by the ratio ($l_{\rm bb}/l_{\rm x}$) between the uv/optical and x-ray luminosities, shows a wide range $l_{\rm bb}/l_{\rm x} \in (0.5, 3000)$ at early-times, and converges to disk-like values $l_{\rm bb}/l_{\rm x} \in (0.5, 10)$ at late-times. the evolution of the derived physical parameters favors a decrease in the optical depth of a reprocessing layer instead of delayed disk formation to explain the late-time x-ray brightening found in several sources. we estimate the fraction of optically discovered tdes with $l_{\rm x}\geq 10^{42}$ erg s$^{-1}$ to be at least $40\%$, and find that the x-ray loudness is independent of black hole mass. we combine our sample with those from x-ray surveys to construct an x-ray luminosity function, best fitted by a broken power-law with a brake at $\sim 10^{44}$ erg s$^{-1}$. we show that there is no dichotomy between optically and x-ray selected tdes; instead, there is a continuum of early time $l_{\rm bb}/l_{\rm x}$, at least as wide as $l_{\rm bb}/l_{\rm x} \in (0.1, 3000)$, with optical/x-ray surveys selecting preferentially, but not exclusively, from the higher/lower end of the distribution. our findings are consistent with an orientation-dependent and time-evolving reprocessing layer, and support viewing-angle unification models. | a systematic analysis of the x-ray emission in optically selected tidal disruption events: observational evidence for the unification of the optically and x-ray selected populations |
spectra of the highest redshift galaxies taken with jwst are now allowing us to see into the heart of the reionization epoch. many of these observed galaxies exhibit strong damping wing absorption redward of their lyman-$\alpha$ emission. these observations have been used to measure the redshift evolution of the neutral fraction of the intergalactic medium and sizes of ionized bubbles. however, these estimates have been made using a simple analytic model for the intergalactic damping wing. we explore the recent observations with models of inhomogeneous reionization from the sherwood-relics simulation suite. we carry out a comparison between the damping wings calculated from the simulations and from the analytic model. we find that although the agreement is good on the red side of the lyman-$\alpha$ emission, there is a discrepancy on the blue side due to residual neutral hydrogen present in the simulations, which saturates the intergalactic absorption. for this reason, we find that it is difficult to reproduce the claimed observations of large bubble sizes at z ~ 7, which are driven by a detection of transmitted flux blueward of the lyman-$\alpha$ emission. we suggest instead that the observations can be explained by a model with smaller ionized bubbles and larger intrinsic lyman-$\alpha$ emission from the host galaxy. | jwst observations of galaxy damping wings during reionization interpreted with cosmological simulations |
high-resolution james webb space telescope (jwst) observations can test confusion-limited hubble space telescope (hst) observations for a photometric bias that could affect extragalactic cepheids and the determination of the hubble constant. we present jwst nircam observations in two epochs and three filters of >320 cepheids in ngc 4258 (which has a 1.5% maser-based geometric distance) and in ngc 5584 (host of sn ia 2007af), near the median distance of the sh0es hst sn ia host sample and with the best leverage among them to detect such a bias. jwst provides far superior source separation from line-of-sight companions than hst in the near-infrared to largely negate confusion or crowding noise at these wavelengths, where extinction is minimal. the result is a remarkable >2.5× reduction in the dispersion of the cepheid period-luminosity relations, from 0.45 to 0.17 mag, improving individual cepheid precision from 20% to 7%. two-epoch photometry confirmed identifications, tested jwst photometric stability, and constrained cepheid phases. the p-l relation intercepts are in very good agreement, with differences (jwst-hst) of 0.00 ± 0.03 and 0.02 ± 0.03 mag for ngc 4258 and ngc 5584, respectively. the difference in the determination of h0 between hst and jwst from these intercepts is 0.02 ± 0.04 mag, insensitive to jwst zero-points or count rate nonlinearity thanks to error cancellation between rungs. we explore a broad range of analysis variants (including passband combinations, phase corrections, measured detector offsets, and crowding levels) indicating robust baseline results. these observations provide the strongest evidence yet that systematic errors in hst cepheid photometry do not play a significant role in the present hubble tension. upcoming jwst observations of >12 sn ia hosts should further refine the local measurement of the hubble constant. | crowded no more: the accuracy of the hubble constant tested with high-resolution observations of cepheids by jwst |
the optically thin critical densities and the effective excitation densities to produce a 1 k km/s (or 0.818 jy km/s $(\frac{\nu_{jk}}{100 \rm{ghz}})^2 \, (\frac{\theta_{beam}}{10^{\prime\prime}})^2$) spectral line are tabulated for 12 commonly observed dense gas molecular tracers. the dependence of the critical density and effective excitation density on physical assumptions (i.e. gas kinetic temperature and molecular column density) is analyzed. critical densities for commonly observed dense gas transitions in molecular clouds (i.e. hcn $1-0$, hco$^+$ $1-0$, n$_2$h$^+$ $1-0$) are typically $1 - 2$ orders of magnitude larger than effective excitation densities because the standard definitions of critical density do not account for radiative trapping and 1 k km/s lines are typically produced when radiative rates out of the upper energy level of the transition are faster than collisional depopulation. the use of effective excitation density has a distinct advantage over the use of critical density in characterizing the differences in density traced by species such as nh$_3$, hco$^+$, n$_2$h$^+$, and hcn as well as their isotpologues; but, the effective excitation density has the disadvantage that it is undefined for transitions when $e_u/k \gg t_k$, for low molecular column densities, and for heavy molecules with complex spectra (i.e. ch$_3$cho). | the critical density and the effective excitation density of commonly observed molecular dense gas tracers |
we study the possible gravitational wave signal and the viability of baryogenesis arising from the electroweak phase transition in an extension of the standard model (sm) by a scalar singlet field without a &z;2 symmetry. we first analyze the velocity of the expanding true-vacuum bubbles during the phase transition, confirming our previous finding in the unbroken &z;2 symmetry scenario, where the bubble wall velocity can be computed from first principles only for weak transitions with strength parameters α ≲ 0.05, and the chapman-jouguet velocity defines the maximum velocity for which the wall is stopped by the friction from the plasma. we further provide an analytical approximation to the wall velocity in the general scalar singlet scenario without &z;2 symmetry and test it against the results of a detailed calculation, finding good agreement. we show that in the singlet scenario with a spontaneously broken &z;2 symmetry, the phase transition is always weak and we see no hope for baryogenesis. in contrast, in the case with explicit &z;2 breaking there is a region of the parameter space producing a promising baryon yield in the presence of cp violating interactions via an effective operator involving the singlet scalar and the sm top quarks. yet, we find that this region yields unobservable gravitational waves. finally, we show that the promising region for baryogenesis in this model may be fully tested by direct searches for singlet-like scalars in di-boson final states at the hl-lhc, combined with present and future measurements of the electron electric dipole moment. | the scalar singlet extension of the standard model: gravitational waves versus baryogenesis |
the pulsar timing array (pta) collaborations have recently suggested the presence of a gravitational wave background at nano-hertz frequencies. in this paper, we explore potential inflationary interpretation of this signal within the context of a simple and health parity-violating gravity model termed the nieh-yan modified teleparallel gravity. through this model, two inflationary scenarios are evaluated, both yielding significant polarized primordial gravitational waves (pgws) that align well with the results from pta observations. furthermore, the resulting pgws can display strong circular polarization and significant anisotropies in the pta frequency band, which are distinct features to be verified by observations of both pta and the cosmic microwave background.the detection of such a distinctive background of pgws is expected to provide strong evidence supporting our scenarios and insights into inflationary dynamics and gravity theory. | explaining pulsar timing array observations with primordial gravitational waves in parity-violating gravity |
we search for strongly lensed and multiply imaged gravitational wave signals in the second observing run of advanced ligo and advanced virgo (o2). we exploit a new source of information, the so-called morse phase, which further mitigates the search background and constrains viable lenses. the best candidate we find is consistent with a strongly lensed signal from a massive binary black hole (bbh) merger, with three detected images consisting of the previously catalogued events gw170104 and gw170814, and a subthreshold trigger, gwc170620. given the number of bbh events detected so far, we estimate an overall false alarm probability $\sim 10^{-4}$ for the observed high degree of parameter coincidence between the three events. on the flip side, we measure the morse phase differences which suggest a complex and atypical lens system, with at least five images including a magnified image at a local maximum of the fermat potential. the low prior probability for multiple lensed images and the amount of fine tuning required in the lens model reduce the credibility of the lensing hypothesis. the long time delays between lensed images point toward a galaxy cluster lens with an internal velocity dispersion $\sigma \sim 650\,{\rm km/s}$, and the observed strain amplitudes imply a likely range $0.4 < z \lesssim 0.7$ for the source redshift. we provide an error ellipse of $\sim 16\,{\rm deg}^2$ for the sky location of the source together with additional specific constraints on the lens-host system, and encourage follow-up efforts to confirm or rule out any viable lens. if this is indeed a lensed event, successfully pinpointing the system would offer a unique opportunity to identify the host galaxy of a bbh merger, and even localize the source within it. | search for lensed gravitational waves including morse phase information: an intriguing candidate in o2 |
we perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography, and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg2 of imaging data by the kilo degree survey (kids-450) overlapping with two spectroscopic surveys: the 2-degree field lensing survey (2dflens) and the baryon oscillation spectroscopic survey (boss). we restrict the galaxy-galaxy lensing and multipole power spectrum measurements to the overlapping regions with kids, and self-consistently compute the full covariance between the different observables using a large suite of n-body simulations. we methodically analyse different combinations of the observables, finding that the galaxy-galaxy lensing measurements are particularly useful in improving the constraint on the intrinsic alignment amplitude, while the multipole power spectra are useful in tightening the constraints along the lensing degeneracy direction. the fully combined constraint on s_8 ≡ σ _8 √{ω _m/0.3}=0.742± 0.035, which is an improvement by 20 per cent compared to kids alone, corresponds to a 2.6σ discordance with planck, and is not significantly affected by fitting to a more conservative set of scales. given the tightening of the parameter space, we are unable to resolve the discordance with an extended cosmology that is simultaneously favoured in a model selection sense, including the sum of neutrino masses, curvature, evolving dark energy and modified gravity. the complementarity of our observables allows for constraints on modified gravity degrees of freedom that are not simultaneously bounded with either probe alone, and up to a factor of three improvement in the s8 constraint in the extended cosmology compared to kids alone. | kids-450 + 2dflens: cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering |
several unexpected features have been observed in the microwave sky at large angular scales, both by wmap and by planck. among those features is a lack of both variance and correlation on the largest angular scales, alignment of the lowest multipole moments with one another and with the motion and geometry of the solar system, a hemispherical power asymmetry or dipolar power modulation, a preference for odd parity modes and an unexpectedly large cold spot in the southern hemisphere. the individual p-values of the significance of these features are in the per mille to per cent level, when compared to the expectations of the best-fit inflationary λcdm model. some pairs of those features are demonstrably uncorrelated, increasing their combined statistical significance and indicating a significant detection of cmb features at angular scales larger than a few degrees on top of the standard model. despite numerous detailed investigations, we still lack a clear understanding of these large-scale features, which seem to imply a violation of statistical isotropy and scale invariance of inflationary perturbations. in this contribution we present a critical analysis of our current understanding and discuss several ideas of how to make further progress. | cmb anomalies after planck |
two experiments from the fermilab, e989 and cdf ii, have reported two anomalies for muon g - 2 and w-boson mass that may indicate the new physics at the low energy scale. here we examine the possibility of a common origin of these two anomalies in the next-to-minimal supersymmetric standard model. considering various experimental and astrophysical constraints such as the higgs mass, collider data, flavor physics, dark matter relic density, and direct detection experiments, we find that lighter electroweakinos and sleptons can generate sufficient contributions to muon g - 2 and mw. moreover, the corresponding bino-like neutralino dark matter mass is in the ∼ 180-280 gev range. interestingly, the favored dark matter (dm) mass region can soon be entirely probed by ongoing direct detection experiments like pandax-4t, xenonnt, lux-zeplin, and darwin. | nmssm neutralino dark matter for cdf ii w-boson mass and muon g - 2 and the promising prospect of direct detection |
we heal the cosmological constant problem by means of a cancellation mechanism that adopts a phase transition during which quantum fluctuations are eliminated. to this purpose, we propose that a generalized scalar (dark) matter field with a non-vanishing pressure term can remove the vacuum energy contribution, if its corresponding thermodynamics is written in terms of a quasi-quintessence representation. in such a picture, pressure differs from quintessence as it shows a zero kinetic contribution. using this field, we investigate a metastable transition phase, in which the universe naturally passes through an inflationary phase. to reach this target, we single out a double exponential potential, describing the metastable inflationary dynamics by considering suitable boundaries and thermodynamic conditions. we analyze stability investigating saddle, stable and unstable points and we thus predict a chaotic inflation that mimics the starobinsky exponential potential. consequently, the role of the proposed dark matter field is investigated throughout the overall universe evolution. to do so, we provide a physical explanation on unifying the dark sector with inflation by healing the cosmological constant problem. | healing the cosmological constant problem during inflation through a unified quasi-quintessence matter field |
combining the stochastic and formalisms, we derive non-perturbative analytical expressions for all correlation functions of scalar perturbations in single-field, slow-roll inflation. the standard, classical formulas are recovered as saddle-point limits of the full results. this yields a classicality criterion that shows that stochastic effects are small only if the potential is sub-planckian and not too flat. the saddle-point approximation also provides an expansion scheme for calculating stochastic corrections to observable quantities perturbatively in this regime. in the opposite regime, we show that a strong suppression in the power spectrum is generically obtained, and we comment on the physical implications of this effect. | correlation functions in stochastic inflation |
the concordance of the λcdm cosmological model in light of current observations has been the subject of an intense debate in recent months. the 2018 planck cosmic microwave background (cmb) temperature anisotropy power spectrum measurements appear at face value to favour a spatially closed universe with curvature parameter ωk < 0 . this preference disappears if baryon acoustic oscillation (bao) measurements are combined with planck data to break the geometrical degeneracy, although the reliability of this combination has been questioned due to the strong tension present between the two datasets when assuming a curved universe. here, we approach this issue from yet another point of view, using measurements of the full-shape (fs) galaxy power spectrum, p(k) , from the baryon oscillation spectroscopic survey dr12 cmass sample. by combining planck data with fs measurements, we break the geometrical degeneracy and find ωk = 0 . 0023 ± 0 . 0028 . this constrains the universe to be spatially flat to sub-percent precision, in excellent agreement with results obtained using bao measurements. however, as with bao, the overall increase in the best-fit χ2 suggests a similar level of tension between planck and p(k) under the assumption of a curved universe. while the debate on spatial curvature and the concordance between cosmological datasets remains open, our results provide new perspectives on the issue, highlighting the crucial role of fs measurements in the era of precision cosmology. | the galaxy power spectrum take on spatial curvature and cosmic concordance |
primordial black holes (pbhs) can be produced by a range of mechanisms in the early universe. a particular formation channel that connects pbhs with inflationary phenomenology invokes enhanced primordial curvature perturbations at small scales. in this paper, we re-examine the impact of the growth of the primordial power spectrum on pbh formation in terms of its implications for the pbh mass function. we elaborate on how rapidly the background can transition between different values of the parameters of the hubble hierarchy, which must ultimately derive from a consistent derivative expansion for the background inflaton field. we discuss artefacts associated with matching calculations, and highlight the robustness of the $k^4$ steepest growth previously found for single-field inflation with conservatively smoothed transitions and limits on how much the amplitude of the power spectrum can grow. we show that the mass function is relatively insensitive to the steepness of the growth of the power spectrum and subsequent decay, depending primarily on the peak amplitude and the presence of any plateaus that last more than an e-fold. the shape of the power spectrum can of course be constrained by other tracers, and so understanding the physical limitations on its shape remains a pertinent question. | steepest growth re-examined: repercussions for primordial black hole formation |
we report the detection of a high density of redshift z ≈ 10 galaxies behind the foreground cluster a2744, selected from imaging data obtained recently with nircam on board jwst by three programs-glass-jwst, uncover, and ddt#2756. to ensure robust estimates of the lensing magnification μ, we use an improved version of our model that exploits the first epoch of nircam images and newly obtained muse spectra and avoids regions with μ > 5 where the uncertainty may be higher. we detect seven bright z ≈ 10 galaxies with demagnified rest frame -22 ≲ m uv ≲ -19 mag, over an area of ~37 arcmin2. taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of z ≈ 10 galaxies in the field is about 10× (3×) larger than the average at m uv ≈ -21 ( -20) mag reported so far. the density is even higher when considering only the glass-jwst data, which are the deepest and the least affected by magnification and incompleteness. the glass-jwst field contains five out of seven galaxies, distributed along an apparent filamentary structure of 2 mpc in projected length, and includes a close pair of candidates with m uv < -20 mag having a projected separation of only 16 kpc. these findings suggest the presence of a z ≈ 10 overdensity in the field. in addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early jwst observations but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering. | early results from glass-jwst. xix. a high density of bright galaxies at z ≈ 10 in the a2744 region |
to gain understanding of the complicated, non-linear, and numerical processes associated with the tidal evolution of dark matter subhaloes in numerical simulation, we perform a large suite of idealized simulations that follow individual n-body subhaloes in a fixed, analytical host halo potential. by varying both physical and numerical parameters, we investigate under what conditions the subhaloes undergo disruption. we confirm the conclusions from our more analytical assessment in van den bosch et al. that most disruption is numerical in origin; as long as a subhalo is resolved with sufficient mass and force resolution, a bound remnant survives. this implies that state-of-the-art cosmological simulations still suffer from significant overmerging. we demonstrate that this is mainly due to inadequate force softening, which causes excessive mass loss and artificial tidal disruption. in addition, we show that subhaloes in n-body simulations are susceptible to a runaway instability triggered by the amplification of discreteness noise in the presence of a tidal field. these two processes conspire to put serious limitations on the reliability of dark matter substructure in state-of-the-art cosmological simulations. we present two criteria that can be used to assess whether individual subhaloes in cosmological simulations are reliable or not, and advocate that subhaloes that satisfy either of these two criteria be discarded from further analysis. we discuss the potential implications of this work for several areas in astrophysics. | dark matter substructure in numerical simulations: a tale of discreteness noise, runaway instabilities, and artificial disruption |
we study cosmic-ray-atmosphere collisions as a permanent production source of exotic millicharged particles (mcps) for all terrestrial experiments. [mcps are also known as charged massive particles (champs).] based on data from super-k, this allows us to derive new limits on mcps that are competitive with, or improve, the currently leading bounds from accelerator-based searches for masses up to 1.5 gev. in models where a subdominant component of dark matter (dm) is fractionally charged, these constraints probe parts of the parameter space that is inaccessible for conventional direct-detection dm experiments, independently of assumptions about the dm abundance. | constraints on millicharged particles from cosmic-ray production |
the search for the curl component (b mode) in the cosmic microwave background (cmb) polarization induced by inflationary gravitational waves is described. the canonical single-field slow-roll model of inflation is presented, and we explain the quantum production of primordial density perturbations and gravitational waves. it is shown how these gravitational waves then give rise to polarization in the cmb. we then describe the geometric decomposition of the cmb polarization pattern into a curl-free component (e mode) and curl component (b mode) and show explicitly that gravitational waves induce b modes. we discuss the b modes induced by gravitational lensing and by galactic foregrounds and show how both are distinguished from those induced by inflationary gravitational waves. issues involved in the experimental pursuit of these b modes are described, and we summarize some of the strategies being pursued. we close with a brief discussion of some other avenues toward detecting/characterizing the inflationary gravitational-wave background. | the quest for b modes from inflationary gravitational waves |
detection of the icecube-170922a neutrino coincident with the flaring blazar txs 0506+056, the first and only ∼3σ high-energy neutrino source association to date, offers a potential breakthrough in our understanding of high-energy cosmic particles and blazar physics. we present a comprehensive analysis of txs 0506+056 during its flaring state, using newly collected swift, nustar, and x-shooter data with fermi observations and numerical models to constrain the blazar’s particle acceleration processes and multimessenger (electromagnetic (em) and high-energy neutrino) emissions. accounting properly for em cascades in the emission region, we find a physically consistent picture only within a hybrid leptonic scenario, with γ-rays produced by external inverse-compton processes and high-energy neutrinos via a radiatively subdominant hadronic component. we derive robust constraints on the blazar’s neutrino and cosmic-ray emissions and demonstrate that, because of cascade effects, the 0.1-100 kev emissions of txs 0506+056 serve as a better probe of its hadronic acceleration and high-energy neutrino production processes than its gev-tev emissions. if the icecube neutrino association holds, physical conditions in the txs 0506+056 jet must be close to optimal for high-energy neutrino production, and are not favorable for ultrahigh-energy cosmic-ray acceleration. alternatively, the challenges we identify in generating a significant rate of icecube neutrino detections from txs 0506+056 may disfavor single-zone models, in which γ-rays and high-energy neutrinos are produced in a single emission region. in concert with continued operations of the high-energy neutrino observatories, we advocate regular x-ray monitoring of txs 0506+056 and other blazars in order to test single-zone blazar emission models, clarify the nature and extent of their hadronic acceleration processes, and carry out the most sensitive possible search for additional multimessenger sources. | a multimessenger picture of the flaring blazar txs 0506+056: implications for high-energy neutrino emission and cosmic-ray acceleration |
the central radio source in m87 provides the best opportunity to study jet formation because it has a large angular size for the gravitational radius of the black hole and has a bright jet that is well resolved by very long baseline interferometry observations. we present intensive monitoring observations from 2007 and 2008, plus roughly annual observations that span 17 years, all made with the the very long baseline array at 43 ghz with a resolution of about 30 by 60r s. our high dynamic range images clearly show the wide opening angle structure and the counterjet. the jet and counterjet are nearly symmetric in the inner 1.5 mas (0.12 pc in projection), with both being edge brightened. both show deviations from parabolic shape in the form of an initial rapid expansion and subsequent contraction followed by further rapid expansion and, beyond the visible counterjet, subsequent collimation. proper motions and counterjet/jet intensity ratios both indicate acceleration from apparent speeds of ≲0.5c to ≳2c in the inner ∼2 mas and suggest a helical flow. the jet displays a sideways shift with an approximately 8-10 yr quasi-periodicity. the shift propagates outward nonballistically and significantly more slowly than the flow speed revealed by the fastest-moving components. polarization data show a systematic structure with magnetic field vectors that suggest a toroidal field close to the core. | the structure and dynamics of the subparsec jet in m87 based on 50 vlba observations over 17 years at 43 ghz |
the recent observation of the shadow of the supermassive black hole m87*, located at the center of the m87 galaxy, by the event horizon telescope collaboration has opened up a new window to probe the strong gravity regime. in this paper, we explicitly demonstrate the consequences of this observation on brane world black holes, characterized by existence of a negative tidal charge. our results based on three observables associated with the shadow, namely, angular diameter, deviation from circularity, and axis ratio reveal that the existence of a negative tidal charge is more favored, possibly marking a deviation from general relativity. | silhouette of m87*: a new window to peek into the world of hidden dimensions |
we develop an exact formalism for the computation of the abundance of primordial black holes (pbhs) in the presence of local non-gaussianity (ng) in the curvature perturbation field. for the first time, we include ng going beyond the widely used quadratic and cubic approximations, and consider a completely generic functional form. adopting threshold statistics on the compaction function, we address the computation of the abundance both for narrow and broad power spectra. while our formulas are generic, we discuss explicit examples of phenomenological relevance considering the physics case of the curvaton field. we carefully assess under which conditions the conventional perturbative approach can be trusted. in the case of a narrow power spectrum, this happens only if the perturbative expansion is pushed beyond the quadratic order (with the optimal order of truncation that depends on the width of the spectrum). most importantly, we demonstrate that the perturbative approach is intrinsically flawed when considering broad spectra, in which case only the nonperturbative computation captures the correct result. finally, we describe the phenomenological relevance of our results for the connection between the abundance of pbhs and the stochastic gravitational wave (gw) background related to their formation. as ngs modify the amplitude of perturbations necessary to produce a given pbh abundance and boost pbh production at large scales for broad spectra, modeling these effects is crucial to connect the pbh scenario to its signatures at current and future gw experiments. | primordial non-gaussianity up to all orders: theoretical aspects and implications for primordial black hole models |
the stochastic gravitational wave background (sgwb) detected recently by the pulsar timing arrays (ptas) observations may have cosmological origins. in this work we consider a model of single field inflation containing an intermediate phase of ultra slow-roll. fixing the amplitude of the peak of curvature perturbations by the pbhs bounds we calculate the gravitational waves (gws) induced from the curvature perturbations enhanced during usr. the spectrum of the induced gws depends on the sharpness of the transition from the usr phase to the final attractor phase as well as to the duration of the usr period. while the model can accommodate the current ptas data but it has non-trivial predictions for the induced gws on higher frequency ranges which can be tested by future observations. | induced gravitational waves from ultra slow-roll inflation and pulsar timing arrays observations |
we present the results obtained from the full-shape cosmology analysis of the redshift-space power spectra for four galaxy samples of the sdss-iii boss dr12 galaxy catalog over 0.2 <z <0.75 . for the theoretical template, we use an emulator that was built from an ensemble set of n -body simulations, which enables fast and accurate computation of the redshift-space power spectrum of "halos." combining with the halo occupation distribution to model the galaxy-halo connection, we can compute the redshift-space power spectrum of boss-like galaxies in less than a cpu second, for an input model under flat λ cdm cosmology. in our cosmology inference, we use the monopole, quadrupole, and hexadecapole moments of the redshift-space power spectrum and include seven nuisance parameters, with broad priors, to model uncertainties in the galaxy-halo connection for each galaxy sample, but do not use any information on the abundance of galaxies. we demonstrate a validation of our analysis pipeline using the mock catalogs of boss-like galaxies, generated using different recipes of the galaxy-halo connection and including the assembly bias effect. assuming weak priors on cosmological parameters, except for the bbn prior on ωbh2 and the cmb prior on ns, we show that our model well reproduces the boss power spectra. including the power-spectrum information up to kmax=0.25 h mpc-1, we find ωm=0.30 1-0.011+0.012, h0=68.2 ±1.4 km s-1 mpc-1, and σ8=0.78 6-0.037+0.036 for the mode and 68% credible interval, after marginalization over galaxy-halo connection parameters. we find little improvement in the cosmological parameters beyond a maximum wavelength kmax≃0.2 h mpc-1 due to the shot noise domination and marginalization of the galaxy-halo connection parameters. our results are consistent with the planck cmb results within 1 σ statistical uncertainties. | full-shape cosmology analysis of the sdss-iii boss galaxy power spectrum using an emulator-based halo model: a 5% determination of σ8 |
we survey systematically the general parametrisations of particle-physics models for a first-order phase transition in the early universe, including models with polynomial potentials both with and without barriers at zero temperature, and coleman-weinberg-like models with potentials that are classically scale-invariant. we distinguish three possibilities for the transition—detonations, deflagrations and hybrids—and consider sound waves and turbulent mechanisms for generating gravitational waves during the transitions in these models, checking in each case the requirement for successful percolation. we argue that in models without a zero-temperature barrier and in scale-invariant models the period during which sound waves generate gravitational waves lasts only for a fraction of a hubble time after a generic first-order cosmological phase transition, whereas it may last longer in some models with a zero-temperature barrier that feature severe supercooling. we illustrate the implications of these results for future gravitational-wave experiments. | gravitational waves from first-order cosmological phase transitions: lifetime of the sound wave source |
using γ -ray data from the fermi large area telescope, various groups have identified a clear excess emission in the inner galaxy, at energies around a few gev. this excess resembles remarkably well a signal from dark-matter annihilation. one of the most compelling astrophysical interpretations is that the excess is caused by the combined effect of a previously undetected population of dim γ -ray sources. because of their spectral similarity, the best candidates are millisecond pulsars. here, we search for this hypothetical source population, using a novel approach based on wavelet decomposition of the γ -ray sky and the statistics of gaussian random fields. using almost seven years of fermi-lat data, we detect a clustering of photons as predicted for the hypothetical population of millisecond pulsar, with a statistical significance of 10.0 σ . for plausible values of the luminosity function, this population explains 100% of the observed excess emission. we argue that other extragalactic or galactic sources, a mismodeling of galactic diffuse emission, or the thick-disk population of pulsars are unlikely to account for this observation. | strong support for the millisecond pulsar origin of the galactic center gev excess |
the kilo-degree survey (kids) is a multi-band imaging survey designed for cosmological studies from weak lensing and photometric redshifts. it uses the european southern observatory vlt survey telescope with its wide-field camera omegacam. kids images are taken in four filters similar to the sloan digital sky survey ugri bands. the best seeing time is reserved for deep r-band observations. the median 5σ limiting ab magnitude is 24.9 and the median seeing is below 0.7 arcsec. initial kids observations have concentrated on the galaxy and mass assembly (gama) regions near the celestial equator, where extensive, highly complete redshift catalogues are available. a total of 109 survey tiles, 1 square degree each, form the basis of the first set of lensing analyses of halo properties of gama galaxies. nine galaxies per square arcminute enter the lensing analysis, for an effective inverse shear variance of 69 arcmin-2. accounting for the shape measurement weight, the median redshift of the sources is 0.53. kids data processing follows two parallel tracks, one optimized for weak lensing measurement and one for accurate matched-aperture photometry (for photometric redshifts). this technical paper describes the lensing and photometric redshift measurements (including a detailed description of the gaussian aperture and photometry pipeline), summarizes the data quality and presents extensive tests for systematic errors that might affect the lensing analyses. we also provide first demonstrations of the suitability of the data for cosmological measurements, and describe our blinding procedure for preventing confirmation bias in the scientific analyses. the kids catalogues presented in this paper are released to the community through http://kids.strw.leidenuniv.nl. | gravitational lensing analysis of the kilo-degree survey |
for primordial black holes (pbh) to be the dark matter in single-field inflation, the slow-roll approximation must be violated by at least o (1 ) in order to enhance the curvature power spectrum within the required number of e -folds between cosmic microwave background scales and pbh mass scales. power spectrum predictions which rely on the inflaton remaining on the slow-roll attractor can fail dramatically leading to qualitatively incorrect conclusions in models like an inflection potential and misestimate the mass scale in a running mass model. we show that an optimized temporal evaluation of the hubble slow-roll parameters to second order remains a good description for a wide range of pbh formation models where up to a 1 07 amplification of power occurs in 10 e -folds or more. | primordial black holes and slow-roll violation |
this paper reviews scalar-tensor theories characterized by a lagrangian that, despite the presence of second-order derivatives, contains a single scalar degree of freedom. these theories, known as degenerate higher-order scalar-tensor (dhost) theories, include horndeski and beyond horndeski theories. they propagate a single scalar mode as a consequence of the degeneracy of their lagrangian and, therefore, are not plagued by an ostrogradsky instability. they have been fully classified up to cubic order in second-order derivatives. the study of their phenomenological consequences restricts the subclass of dhost theories that are compatible with observations. in cosmology, these theories can be described in the language of the unified effective approach to dark energy and modified gravity. compact objects in the context of dhost theories are also discussed. | dark energy and modified gravity in degenerate higher-order scalar-tensor (dhost) theories: a review |
cosmological observations are a powerful probe of neutrino properties, and in particular of their mass. in this review, we first discuss the role of neutrinos in shaping the cosmological evolution at both the background and perturbation level, and describe their effects on cosmological observables such as the cosmic microwave background and the distribution of matter at large scale. we then present the state of the art concerning the constraints on neutrino masses from those observables, and also review the prospects for future experiments. we also briefly discuss the prospects for determining the neutrino hierarchy from cosmology, the complementarity with laboratory experiments, and the constraints on neutrino properties beyond their mass. | status of neutrino properties and future prospects - cosmological and astrophysical constraints |
we present galaxy zoo decals: detailed visual morphological classifications for dark energy camera legacy survey images of galaxies within the sdss dr8 footprint. deeper decals images (r = 23.6 versus r = 22.2 from sdss) reveal spiral arms, weak bars, and tidal features not previously visible in sdss imaging. to best exploit the greater depth of decals images, volunteers select from a new set of answers designed to improve our sensitivity to mergers and bars. galaxy zoo volunteers provide 7.5 million individual classifications over 314 000 galaxies. 140 000 galaxies receive at least 30 classifications, sufficient to accurately measure detailed morphology like bars, and the remainder receive approximately 5. all classifications are used to train an ensemble of bayesian convolutional neural networks (a state-of-the-art deep learning method) to predict posteriors for the detailed morphology of all 314 000 galaxies. we use active learning to focus our volunteer effort on the galaxies which, if labelled, would be most informative for training our ensemble. when measured against confident volunteer classifications, the trained networks are approximately 99 per cent accurate on every question. morphology is a fundamental feature of every galaxy; our human and machine classifications are an accurate and detailed resource for understanding how galaxies evolve. | galaxy zoo decals: detailed visual morphology measurements from volunteers and deep learning for 314 000 galaxies |
we review the field of collisionless numerical simulations for the large-scale structure of the universe. we start by providing the main set of equations solved by these simulations and their connection with general relativity. we then recap the relevant numerical approaches: discretization of the phase-space distribution (focusing on n-body but including alternatives, e.g., lagrangian submanifold and schrödinger-poisson) and the respective techniques for their time evolution and force calculation (direct summation, mesh techniques, and hierarchical tree methods). we pay attention to the creation of initial conditions and the connection with lagrangian perturbation theory. we then discuss the possible alternatives in terms of the micro-physical properties of dark matter (e.g., neutralinos, warm dark matter, qcd axions, bose-einstein condensates, and primordial black holes), and extensions to account for multiple fluids (baryons and neutrinos), primordial non-gaussianity and modified gravity. we continue by discussing challenges involved in achieving highly accurate predictions. a key aspect of cosmological simulations is the connection to cosmological observables, we discuss various techniques in this regard: structure finding, galaxy formation and baryonic modelling, the creation of emulators and light-cones, and the role of machine learning. we finalise with a recount of state-of-the-art large-scale simulations and conclude with an outlook for the next decade. | large-scale dark matter simulations |
is dark matter part of a dark sector? the possibility of a dark sector neutral under standard model (sm) forces furnishes an attractive explanation for the existence of dark matter (dm), and is a compelling new-physics direction to explore in its own right, with potential relevance to fundamental questions as varied as neutrino masses, the hierarchy problem, and the universe's matter-antimatter asymmetry. because dark sectors are generically weakly coupled to ordinary matter, and because they can naturally have mev-to-gev masses and respect the symmetries of the sm, they are only mildly constrained by high-energy collider data and precision atomic measurements. yet upcoming and proposed intensity-frontier experiments will offer an unprecedented window into the physics of dark sectors, highlighted as a priority research direction in the 2018 dark matter new initiatives (dmni) brn report. support for this program -- in the form of dark-sector analyses at multi-purpose experiments, realization of the intensity-frontier experiments receiving dmni funds, an expansion of dmni support to explore the full breadth of dm and visible final-state signatures (especially long-lived particles) called for in the brn report, and support for a robust dark-sector theory effort -- will enable comprehensive exploration of low-mass thermal dm milestones, and greatly enhance the potential of intensity-frontier experiments to discover dark-sector particles decaying back to sm particles. | dark sector physics at high-intensity experiments |
any abundance of black holes that was present in the early universe will evolve as matter, making up an increasingly large fraction of the total energy density as space expands. this motivates us to consider scenarios in which the early universe included an era that was dominated by low-mass ($m < 5\times 10^8$ g) black holes which evaporate prior to primordial nucleosynthesis. in significant regions of parameter space, these black holes will become gravitationally bound within binary systems, and undergo mergers before evaporating. such mergers result in three potentially observable signatures. first, any black holes that have undergone one or more mergers will possess substantial angular momentum, causing their hawking evaporation to produce significant quantities of high-energy gravitons. these products of hawking evaporation are predicted to constitute a background of hot ($\sim$ev-kev) gravitons today, with an energy density corresponding to $\delta n_{\rm eff} \sim 0.01-0.03$. second, these mergers will produce a stochastic background of high-frequency gravitational waves. and third, the energy density of these gravitational waves can be as large as $\delta n_{\rm eff} \sim 0.3$, depending on the length of time between the mergers and evaporation. these signals are each potentially within the reach of future measurements. | hot gravitons and gravitational waves from kerr black holes in the early universe |
we analyze the parsec-scale jet kinematics from 2007 june to 2013 january of a sample of γ-ray bright blazars monitored roughly monthly with the very long baseline array at 43 ghz. in a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 bl lacertae objects (bllacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5 pc (projected) of the core, and knots in bllacs tending to decelerate near the core. using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability doppler factors, lorentz factors, and viewing angles. we estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. we determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. we calculate the intrinsic brightness temperatures of the cores, {t}{{b},{int}}{core}, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ∼30% of {t}{{b},{int}}{core} measurements in the quasars and bllacs deviate from equipartition values by a factor >10. this probably occurs during transient events connected with active states. in the appendix, we briefly describe the behavior of each blazar during the period analyzed. | kinematics of parsec-scale jets of gamma-ray blazars at 43 ghz within the vlba-bu-blazar program |
we present large-scale structure catalogues from the completed extended baryon oscillation spectroscopic survey (eboss). derived from sloan digital sky survey (sdss) iv data release 16 (dr16), these catalogues provide the data samples, corrected for observational systematics, and random positions sampling the survey selection function. combined, they allow large-scale clustering measurements suitable for testing cosmological models. we describe the methods used to create these catalogues for the eboss dr16 luminous red galaxy (lrg) and quasar samples. the quasar catalogue contains 343 708 redshifts with 0.8 < z < 2.2 over 4808 deg2. we combine 174 816 eboss lrg redshifts over 4242 deg2 in the redshift interval 0.6 < z < 1.0 with sdss-iii boss lrgs in the same redshift range to produce a combined sample of 377 458 galaxy redshifts distributed over 9493 deg2. improved algorithms for estimating redshifts allow that 98 per cent of lrg observations result in a successful redshift, with less than one per cent catastrophic failures (δz > 1000 km s-1). for quasars, these rates are 95 and 2 per cent (with δz > 3000 km s-1). we apply corrections for trends between the number densities of our samples and the properties of the imaging and spectroscopic data. for example, the quasar catalogue obtains a χ2/dof = 776/10 for a null test against imaging depth before corrections and a χ2/dof= 6/8 after. the catalogues, combined with careful consideration of the details of their construction found here-in, allow companion papers to present cosmological results with negligible impact from observational systematic uncertainties. | the completed sdss-iv extended baryon oscillation spectroscopic survey: large-scale structure catalogues for cosmological analysis |
in this work, we consider an extension of symmetric teleparallel gravity, namely, f (q ) gravity, where the fundamental block to describe spacetime is the nonmetricity, q . within this formulation of gravitation, we perform an observational analysis of several modified f (q ) models using the redshift approach, where the f (q ) lagrangian is reformulated as an explicit function of the redshift, f (z ). various different polynomial parametrizations of f (z ) are proposed, including new terms which would allow for deviations from the λ cold dark matter model. given a variety of observational probes, such as the expansion rate data from early type galaxies, type ia supernovae, quasars, gamma ray bursts, baryon acoustic oscillations data, and cosmic microwave background distance priors, we have checked the validity of these models at the background level in order to verify if this new formalism provides us with plausible alternative models to explain the late time acceleration of the universe. indeed, this novel approach provides a different perspective on the formulation of observationally reliable alternative models of gravity. | observational constraints of f (q ) gravity |
gravitational-wave observations of extreme mass ratio inspirals (emris) offer the opportunity to probe the environments of active galactic nuclei (agn) through the torques that accretion disks induce on the binary. within a bayesian framework, we study how well such environmental effects can be measured using gravitational wave observations from the laser interferometer space antenna (lisa). we focus on the torque induced by planetary-type migration on quasicircular inspirals and use different prescriptions for geometrically thin and radiatively efficient disks. we find that lisa could detect migration for a wide range of disk viscosities and accretion rates, for both α and β disk prescriptions. for a typical emri with masses 50 m⊙+106m⊙, we find that lisa could distinguish between migration in α and β disks and measure the torque amplitude with ∼20 % relative precision. provided an accurate torque model, we also show how to turn gravitational-wave measurements of the torque into constraints on the disk properties. furthermore, we show that, if an electromagnetic counterpart is identified, the multimessenger observations of the agn emri system will yield direct measurements of the disk viscosity. finally, we investigate the impact of neglecting environmental effects in the analysis of the gravitational-wave signal, finding 3 σ biases in the primary mass and spin, and showing that ignoring such effects can lead to false detection of a deviation from general relativity. this work demonstrates the scientific potential of gravitational observations as probes of accretion-disk physics, accessible so far through electromagnetic observations only. | probing accretion physics with gravitational waves |
we present constraints on extensions to the standard cosmological model of a spatially flat universe governed by general relativity, a cosmological constant (λ), and cold dark matter (cdm) by varying the spatial curvature ωk, the sum of the neutrino masses ∑mν, the dark energy equation of state parameter w, and the hu-sawicki f(r) gravity fr0 parameter. with the combined 3 × 2 pt measurements of cosmic shear from the kilo-degree survey (kids-1000), galaxy clustering from the baryon oscillation spectroscopic survey (boss), and galaxy-galaxy lensing from the overlap between kids-1000, boss, and the spectroscopic 2-degree field lensing survey, we find results that are fully consistent with a flat λcdm model with ωk = 0.011−0.057+0.054, ∑mν < 1.76 ev (95% cl), and w = −0.99−0.13+0.11. the fr0 parameter is unconstrained in our fully non-linear f(r) cosmic shear analysis. considering three different model selection criteria, we find no clear preference for either the fiducial flat λcdm model or any of the considered extensions. in addition to extensions to the flat λcdm parameter space, we also explore restrictions to common subsets of the flat λcdm parameter space by fixing the amplitude of the primordial power spectrum to the planck best-fit value, as well as adding external data from supernovae and lensing of the cosmic microwave background (cmb). neither the beyond-λcdm models nor the imposed restrictions explored in this analysis are able to resolve the ∼3σ tension in s8 between the 3 × 2 pt constraints and the planck temperature and polarisation data, with the exception of wcdm, where the s8 tension is resolved. the tension in the wcdm case persists, however, when considering the joint s8 − w parameter space. the joint flat λcdm cmb lensing and 3 × 2 pt analysis is found to yield tight constraints on ωm = 0.307−0.013+0.008, σ8 = 0.769−0.010+0.022, and s8 = 0.779−0.013+0.013. | kids-1000 cosmology: constraints beyond flat λcdm |
we derive a lower bound on the merger rate of primordial black hole (pbh) binaries by estimating the maximal fraction of binaries that were perturbed between formation in the early universe and merger, and computing a conservative merger rate of perturbed binaries. this implies robust constraints on the pbh abundance in the range 1 - 100 m⊙ . we further show that ligo/virgo design sensitivity has the potential to reach the pbh mass range of 1 0-2- 1 03m⊙ . the constraint from the merger rate of perturbed binaries is stronger if pbhs are initially spatially clustered. | lower bound on the primordial black hole merger rate |
we outline the science motivation for sgso, the southern gamma-ray survey observatory. sgso will be a next-generation wide field-of-view gamma-ray survey instrument, sensitive to gamma-rays in the energy range from 100 gev to hundreds of tev. its science topics include unveiling galactic and extragalactic particle accelerators, monitoring the transient sky at very high energies, probing particle physics beyond the standard model, and the characterization of the cosmic ray flux. sgso will consist of an air shower detector array, located in south america. due to its location and large field of view, sgso will be complementary to other current and planned gamma-ray observatories such as hawc, lhaaso, and cta. | science case for a wide field-of-view very-high-energy gamma-ray observatory in the southern hemisphere |
late times dark energy transitions at redshifts z ≪0.1 can raise the predicted value of the hubble constant to the sh0es value, 74.03 ±1.42 (km s-1 mpc-1) or more, while providing an equally good fit as λ cdm at 67.73 ±0.41 to higher redshift data, in particular from the cosmic microwave background and baryon acoustic oscillations. these models however do not fully resolve the true source of tension between the distance ladder and high redshift observations: the local calibration of supernovae luminosities well out into the hubble flow. when tested in this manner by transferring the sh0es calibration to the pantheon supernovae dataset, the ability of such transitions to raise the hubble constant is reduced to 69.17 ±1.09 . such an analysis should also be used when testing any dynamical dark energy model which can produce similarly fine features in redshift or local void models. | can late dark energy transitions raise the hubble constant? |
we use redshift-space galaxy clustering data from the boss survey to constrain local primordial non-gaussianity (lpng). this is of particular importance due to the consistency relations, which imply that a detection of lpng would rule out all single-field inflationary models. our constraints are based on the consistently analyzed redshift-space galaxy power spectra and bispectra, extracted from the public boss data with optimal window-free estimators. we use a complete perturbation theory model including all one-loop power spectrum corrections generated by lpng. our constraint on the amplitude of the local non-gaussian shape is fnllocal=-33 ±28 at 68% c.l., yielding no evidence for primordial non-gaussianity. the addition of the bispectrum tightens the fnllocal constraints from boss by 20%, and allows breaking of degeneracies with non-gaussian galaxy bias. these results set the stage for the analysis of future surveys, whose larger volumes will yield significantly tighter constraints on lpng. | constraints on multifield inflation from the boss galaxy survey |
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