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the idea that primordial black holes (pbhs) can comprise most of the dark matter of the universe has recently reacquired a lot of momentum. observational constraints, however, rule out this possibility for most of the pbh masses, with a notable exception around 10-12 m⊙. these light pbhs may be originated when a sizable comoving curvature perturbation generated during inflation reenters the horizon during the radiation phase. during such a stage, it is unavoidable that gravitational waves (gws) are generated. since their source is quadratic in the curvature perturbations, these gws are generated fully non-gaussian. their frequency today is about a millihertz, which is exactly the range where the lisa mission has the maximum of its sensitivity. this is certainly an impressive coincidence. we show that this scenario of pbhs as dark matter can be tested by lisa by measuring the gw two-point correlator. on the other hand, we show that the short observation time (as compared to the age of the universe) and propagation effects of the gws across the perturbed universe from the production point to the lisa detector suppress the bispectrum to an unobservable level. this suppression is completely general and not specific to our model. | testing primordial black holes as dark matter with lisa |
we study the decoupling process of neutrinos in the early universe in the presence of three-flavour oscillations. the evolution of the neutrino spectra is found by solving the corresponding momentum-dependent kinetic equations for the neutrino density matrix, including for the first time the proper collision integrals for both diagonal and off-diagonal elements. this improved calculation modifies the evolution of the off-diagonal elements of the neutrino density matrix and changes the deviation from equilibrium of the frozen neutrino spectra. however, it does not vary the contribution of neutrinos to the cosmological energy density in the form of radiation, usually expressed in terms of the effective number of neutrinos, neff. we find a value of neff = 3.045, in agreement with previous theoretical calculations and consistent with the latest analysis of planck data. this result does not depend on the ordering of neutrino masses. we also consider the effect of non-standard neutrino-electron interactions (nsi), predicted in many theoretical models where neutrinos acquire mass. for two sets of nsi parameters allowed by present data, we find that neff can be reduced down to 3.040 or enhanced up to 3.059. | relic neutrino decoupling with flavour oscillations revisited |
the phenomenon of cosmological gravitational particle production (cgpp) is expected to occur during the period of inflation and the transition into a hot big bang cosmology. particles may be produced even if they only couple directly to gravity, and so cgpp provides a natural explanation for the origin of dark matter. in this work we study the gravitational production of massive spin-2 particles assuming two different couplings to matter. we evaluate the full system of mode equations, including the helicity-0 modes, and by solving them numerically we calculate the spectrum and abundance of massive spin-2 particles that results from inflation on a hilltop potential. we conclude that cgpp might provide a viable mechanism for the generation of massive spin-2 particle dark matter during inflation, and we identify the favorable region of parameter space in terms of the spin-2 particle's mass and the reheating temperature. as a secondary product of our work, we identify the conditions under which such theories admit ghost or gradient instabilities, and we thereby derive a generalization of the higuchi bound to friedmann-robertson-walker (frw) spacetimes. | cosmological gravitational particle production of massive spin-2 particles |
within ten nearby (d < 450 pc) gould belt molecular clouds we evaluate statistically the relative orientation between the magnetic field projected on the plane of sky, inferred from the polarized thermal emission of galactic dust observed by planck at 353 ghz, and the gas column density structures, quantified by the gradient of the column density, nh. the selected regions, covering several degrees in size, are analysed at an effective angular resolution of 10' fwhm, thus sampling physical scales from 0.4 to 40 pc in the nearest cloud. the column densities in the selected regions range from nh≈ 1021 to1023 cm-2, and hence they correspond to the bulk of the molecular clouds. the relative orientation is evaluated pixel by pixel and analysed in bins of column density using the novel statistical tool called "histogram of relative orientations". throughout this study, we assume that the polarized emission observed by planck at 353 ghz is representative of the projected morphology of the magnetic field in each region, i.e., we assume a constant dust grain alignment efficiency, independent of the local environment. within most clouds we find that the relative orientation changes progressively with increasing nh, from mostly parallel or having no preferred orientation to mostly perpendicular. in simulations of magnetohydrodynamic turbulence in molecular clouds this trend in relative orientation is a signature of alfvénic or sub-alfvénic turbulence, implying that the magnetic field is significant for the gas dynamics at the scales probed by planck. we compare the deduced magnetic field strength with estimates we obtain from other methods and discuss the implications of the planck observations for the general picture of molecular cloud formation and evolution. | planck intermediate results. xxxv. probing the role of the magnetic field in the formation of structure in molecular clouds |
new data are reported from the operation of the pico-60 dark matter detector, a bubble chamber filled with 36.8 kg of cf3 i and located in the snolab underground laboratory. pico-60 is the largest bubble chamber to search for dark matter to date. with an analyzed exposure of 92.8 livedays, pico-60 exhibits the same excellent background rejection observed in smaller bubble chambers. alpha decays in pico-60 exhibit frequency-dependent acoustic calorimetry, similar but not identical to that reported recently in a c3 f8 bubble chamber. pico-60 also observes a large population of unknown background events, exhibiting acoustic, spatial, and timing behaviors inconsistent with those expected from a dark matter signal. these behaviors allow for analysis cuts to remove all background events while retaining 48.2% of the exposure. stringent limits on weakly interacting massive particles interacting via spin-dependent proton and spin-independent processes are set, and most interpretations of the dama/libra modulation signal as dark matter interacting with iodine nuclei are ruled out. | dark matter search results from the pico-60 cf3 i bubble chamber |
the selection of high-redshift galaxies often involves spectral energy distribution (sed) fitting to photometric data, an expectation for contamination levels, and measurement of sample completeness-all vetted through comparison to spectroscopic redshift measurements of a sub-sample. the first jwst data are now being taken over several extragalactic fields to different depths and across various areas, which will be ideal for the discovery and classification of galaxies out to distances previously uncharted. as spectroscopic redshift measurements for sources in this epoch will not be initially available to compare with the first photometric measurements of z > 8 galaxies, robust photometric redshifts are of the utmost importance. galaxies at z > 8 are expected to have bluer rest-frame ultraviolet (uv) colors than typically used model sed templates, which could lead to catastrophic photometric redshift failures. we use a combination of bpass and cloudy models to create a supporting set of templates that match the predicted rest-uv colors of z > 8 simulated galaxies. we test these new templates by fitting simulated galaxies in a mock catalog, yung et al., which mimic expected field depths and areas of the jwst cosmic evolution early release science survey (m 5σ~ 28.6 over ~100 arcmin2). we use eazy to highlight the improvements in redshift recovery with the inclusion of our new template set and suggest criteria for selecting galaxies at 8 < z < 10 with the jwst, providing an important test case for observers venturing into this new era of astronomy. | spectral templates optimal for selecting galaxies at z > 8 with the jwst |
motivated by its potential use as a starting point for solving various cosmological constant problems, we study f‑theory compactified on the warped product where y8 is a manifold, and the s3 factor is the target space of an wess–zumino–witten (wzw) model at level n. reduction to m‑theory exploits the abelian duality of this wzw model to an orbifold. in the large n limit, the untwisted sector is captured by 11d supergravity. the local dynamics of intersecting 7‑branes in the geometry is controlled by a donaldson–witten twisted gauge theory coupled to defects. at late times, the system is governed by a 1d quantum mechanics system with a ground state annihilated by two real supercharges, which in four dimensions would appear as " supersymmetry" on a curved background. this leads to a cancellation of zero point energies in the 4d field theory but a split mass spectrum for superpartners of order specified by the ir and uv cutoffs of the model. this is suggestively close to the tev scale in some scenarios. the classical 4d geometry has an intrinsic instability which can produce either a collapsing or expanding universe, the latter providing a promising starting point for a number of cosmological scenarios. the resulting 1d quantum mechanics in the time direction also provides an appealing starting point for a more detailed study of quantum cosmology.motivated by its potential use as a starting point for solving various cosmological constant problems, f‑theory is studied compactified on the warped product rtime × s3 × y8 where y8 is a spin(7) manifold, and the s3 factor is the target space of an su(2) wess–zumino–witten (wzw) model at level n. reduction to m‑theory exploits the abelian duality of this wzw model to an s3/zn orbifold. in the large n limit, the untwisted sector is captured by 11d supergravity. the local dynamics of intersecting 7‑branes in the spin(7) geometry is controlled by a donaldson–witten twisted gauge theory coupled to defects. at late times, the system is governed by a 1d quantum mechanics system with a ground state annihilated by two real supercharges, which in four dimensions would appear as "n = 1/2 supersymmetry" on a curved background. this leads to a cancellation of zero point energies in the 4d field theory but a split mass spectrum for superpartners which is suggestively close to the tev scale in some scenarios. the classical 4d geometry has an intrinsic instability which can produce either a collapsing or expanding universe, the latter providing a promising starting point for a number of cosmological scenarios. the resulting 1d quantum mechanics in the time direction also provides an appealing starting point for a more detailed study of quantum cosmology. | f‑theory and dark energy |
we present the first catalog of gamma-ray sources emitting above 56 and 100 tev with data from the high altitude water cherenkov observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred tev. nine sources are observed above 56 tev, all of which are likely galactic in origin. three sources continue emitting past 100 tev, making this the highest-energy gamma-ray source catalog to date. we report the integral flux of each of these objects. we also report spectra for three highest-energy sources and discuss the possibility that they are pevatrons. | multiple galactic sources with emission above 56 tev detected by hawc |
we investigate the possibility of phantom crossing in the dark energy sector and solution for the hubble tension between early and late universe observations. we use robust combinations of different cosmological observations, namely the cmb, local measurement of hubble constant ($h_0$), bao and snia for this purpose. for a combination of cmb+bao data which is related to early universe physics, phantom crossing in the dark energy sector is confirmed at $95$\% confidence level and we obtain the constraint $h_0=71.0^{+2.9}_{-3.8}$ km/s/mpc at 68\% confidence level which is in perfect agreement with the local measurement by riess et al. we show that constraints from different combination of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. for the combination of all data considered, we obtain the constraint $h_0=70.25\pm 0.78$ km/s/mpc at 68\% confidence level and the phantom crossing happening at the scale factor $a_m=0.851^{+0.048}_{-0.031}$ at 68\% confidence level. | dark energy with phantom crossing and the h0 tension |
we present measurements of the redshift-dependent clustering of a desi-like luminous red galaxy (lrg) sample selected from the legacy survey imaging data set, and use the halo occupation distribution (hod) framework to fit the clustering signal. the photometric lrg sample in this study contains 2.7 million objects over the redshift range of 0.4 < z < 0.9 over 5655 deg2. we have developed new photometric redshift (photo-z) estimates using the legacy survey decam and wise photometry, with σnmad = 0.02 precision for lrgs. we compute the projected correlation function using new methods that maximize signal-to-noise ratio while incorporating redshift uncertainties. we present a novel algorithm for dividing irregular survey geometries into equal-area patches for jackknife resampling. for a five-parameter hod model fit using the multidark halo catalogue, we find that there is little evolution in hod parameters except at the highest redshifts. the inferred large-scale structure bias is largely consistent with constant clustering amplitude over time. in an appendix, we explore limitations of markov chain monte carlo fitting using stochastic likelihood estimates resulting from applying hod methods to n-body catalogues, and present a new technique for finding best-fitting parameters in this situation. accompanying this paper, we have released the photometric redshifts for the legacy surveys catalogue of photo-z's obtained by applying the methods used in this work to the full legacy survey data release 8 data set. this catalogue provides accurate photometric redshifts for objects with z < 21 over more than 16 000 deg2 of sky. | the clustering of desi-like luminous red galaxies using photometric redshifts |
weak galaxy lensing surveys have consistently reported a lower amplitude for the matter fluctuation spectrum, as measured by the s8 parameter, than expected in the λcdm cosmology favoured by planck. however, the expansion history follows the predictions of the planck λcdm cosmology to high accuracy, as do measurements of lensing of the cosmic microwave background anisotropies. redshift space distortion measurements also appear to be consistent with planck λcdm. in this paper, we argue that these observations can be reconciled with the planck λcdm cosmology if the matter power spectrum is suppressed more strongly on non-linear scales than assumed in analyses of weak galaxy lensing. we demonstrate this point by fitting a one-parameter model, characterizing a suppression of the non-linear power spectrum, to the kids-1000 weak lensing measurements. such a suppression could be attributed to new properties of the dark matter that affect non-linear scales, or to a response of the matter fluctuations to baryonic feedback processes that are stronger than expected from recent cosmological simulations. our proposed explanation can be tested using measurements of the amplitude of the matter fluctuation spectrum on linear scales, in particular via high precision redshift space distortion measurements from forthcoming galaxy and quasar redshift surveys. | a non-linear solution to the s8 tension? |
a haloscope of the quax-a γ experiment, composed of an high-q resonant cavity immersed in a 8 t magnet and cooled to ∼4.5 k is operated to search for galactic axions with mass ma≃42.8 μ ev , not accessible to other running experiments. the design of the cavity with hollow dielectric cylinders concentrically inserted in a ofhc cu cavity, allowed us to maintain a loaded quality-factor q ∼300000 during the measurements in presence of magnetic field. through the cavity tuning mechanism it was possible to modulate the resonance frequency of the haloscope in the region 10.35337 −10.35345 ghz and thus acquire different datasets at different resonance frequencies. acquiring each datasets for about 50 minutes, combining them and correcting for the axion's signal estimation-efficiency, we set a limit on the axion-photon coupling ga γ γ<0.731 ×10-13 gev-1 with the confidence level set at 90%. | search for galactic axions with a high-q dielectric cavity |
the early dark energy (ede) solution to the hubble tension comes at the cost of an increased clustering amplitude that has been argued to worsen the fit to galaxy clustering data. we explore whether freeing the total neutrino mass mν, which can suppress small-scale structure growth, improves ede's fit to galaxy clustering. using planck cosmic microwave background and boss galaxy clustering data, a bayesian analysis shows that freeing mν does not appreciably increase the inferred ede fraction fede: we find the 95 per cent c.l. upper limits fede < 0.092 and $m_{\nu }\lt 0.15\, {\rm ev}$. similarly, in a frequentist profile likelihood setting (where our results support previous findings that prior volume effects are important), we find that the baseline ede model (with $m_{\nu }=0.06\, {\rm ev}$) provides the overall best fit. for instance, compared to baseline ede, a model with $m_\nu =0.24\, {\rm ev}$ maintains the same h0(km/s/mpc) = (70.08, 70.11, respectively) whilst decreasing s8 = (0.837, 0.826) to the λcdm level, but worsening the fit significantly by δχ2 = 7.5. for the datasets used, these results are driven not by the clustering amplitude, but by background modifications to the late-time expansion rate due to massive neutrinos, which worsen the fit to measurements of the bao scale. | restoring cosmological concordance with early dark energy and massive neutrinos? |
recently, the hydrogen epoch of reionization array (hera) has produced the experiment's first upper limits on the power spectrum of 21 cm fluctuations at z ~ 8 and 10. here, we use several independent theoretical models to infer constraints on the intergalactic medium (igm) and galaxies during the epoch of reionization from these limits. we find that the igm must have been heated above the adiabatic-cooling threshold by z ~ 8, independent of uncertainties about igm ionization and the radio background. combining hera limits with complementary observations constrains the spin temperature of the z ~ 8 neutral igm to 27 k $\langle {\overline{t}}_{s}\rangle $ 630 k (2.3 k $\langle {\overline{t}}_{s}\rangle $ 640 k) at 68% (95%) confidence. they therefore also place a lower bound on x-ray heating, a previously unconstrained aspects of early galaxies. for example, if the cosmic microwave background dominates the z ~ 8 radio background, the new hera limits imply that the first galaxies produced x-rays more efficiently than local ones. the z ~ 10 limits require even earlier heating if dark-matter interactions cool the hydrogen gas. if an extra radio background is produced by galaxies, we rule out (at 95% confidence) the combination of high radio and low x-ray luminosities of lr,ν /sfr > 4 × 1024 w hz-1 ${m}_{\odot }^{-1}$ yr and lx /sfr < 7.6 × 1039 erg s-1 ${m}_{\odot }^{-1}$ yr. the new hera upper limits neither support nor disfavor a cosmological interpretation of the recent experiment to detect the global eor signature (edges) measurement. the framework described here provides a foundation for the interpretation of future hera results. | hera phase i limits on the cosmic 21 cm signal: constraints on astrophysics and cosmology during the epoch of reionization |
we present measurements of the spectral properties for a total of 526,265 quasars, out of which 63% have a continuum signal-to-noise ratio > 3 pixel-1, selected from the fourteenth data release of the sloan digital sky survey (sdss-dr14) quasar catalog. we performed a careful and homogeneous analysis of the sdss spectra of these sources to estimate the continuum and line properties of several emission lines such as hα, hβ, hγ, mg ii, c iii], c iv, and lyα. from the derived emission line parameters, we estimated single-epoch virial black hole masses (mbh) for the sample using hβ, mg ii, and c iv emission lines. the sample covers a wide range in bolometric luminosity ( $\mathrm{log}{l}_{\mathrm{bol}};$ erg s-1) between 44.4 and 47.3 and $\mathrm{log}{m}_{\mathrm{bh}}$ between 7.1 and 9.9 m⊙. using the ratio of lbol to the eddington luminosity as a measure of the accretion rate, the logarithm of the accretion rate is found to be in the range between -2.06 and 0.43. we performed several correlation analyses between different emission line parameters and found them to match the correlation known earlier using smaller samples. we note that strong fe ii sources with a large balmer line width and highly accreting sources with large mbh are rare in our sample. we make an extended and complete catalog available online that contains various spectral properties of 526,265 quasars derived in this work along with other properties culled from the sdss-dr14 quasar catalog. | spectral properties of quasars from sloan digital sky survey data release 14: the catalog |
for the newly discovered w -boson mass anomaly, one of the simplest dark matter (dm) models that can account for the anomaly without violating other astrophysical and experimental constraints is the inert two higgs doublet model, in which the dm mass (ms) is found to be within ∼54 - 74 gev . in this model, the annihilation of dm via s s →b b ¯ and s s →w w* would produce antiprotons and gamma rays, and may account for the excesses identified previously in both particles. motivated by this, we reanalyze the ams-02 antiproton and fermi-lat galactic center γ -ray data. for the antiproton analysis, the novel treatment is the inclusion of the charge-sign-dependent three-dimensional solar modulation model as constrained by the time-dependent proton data. we find that the excess of antiprotons is more distinct than previous results based on the force-field solar modulation model. the interpretation of this excess as the annihilation of s s →w w* (s s →b b ¯) requires a dm mass of ∼40 - 80 (40-60) gev and a velocity-averaged cross section of o (10-26) cm3 s-1 . as for the γ -ray data analysis, besides adopting the widely used spatial template fitting, we employ an orthogonal approach with a data-driven spectral template analysis. the fitting to the gev γ -ray excess yields dm model parameters overlapped with those to fit the antiproton excess via the w w* channel. the consistency of the dm particle properties required to account for the w -boson mass anomaly, the gev antiproton excess, and the gev γ -ray excess suggests a common origin of them. | explaining the gev antiproton excess, gev γ -ray excess, and w -boson mass anomaly in an inert two higgs doublet model |
we show that a scalar excited state with large occupation numbers during inflation leads to an enhancement of tensor modes and a characteristic pattern of order-one oscillations in the associated stochastic gravitational wave background (sgwb) sourced during inflation. an effective excited state, i.e. a departure from the bunch-davies vacuum, can emerge dynamically as the result of a transient non-adiabatic evolution, e.g. a sharp feature along the inflationary history. we provide an explicit example in a multifield context where the sharp feature triggering the excited state is identified with a strong turn in the inflationary trajectory. en passant, we derive a universal expression for the tensor power spectrum sourced at second order by an arbitrary number of scalar degrees of freedom during inflation, crucially taking into account the nontrivial structure of the hilbert space in multifield setups. the sgwb sourced during inflation can overcome the standard scalar-induced sgwb sourced at horizon re-entry of the fluctuations after inflation, while being less constrained by perturbativity and backreaction bounds. in addition, one may entertain the possibility of detecting both since they peak at different frequencies exhibiting oscillations with distinct periods. | primordial gravitational waves from excited states |
the energy spectrum of high-energy neutrinos reported by the icecube collaboration shows a dip between 400 tev and 1 pev. one intriguing explanation is that high-energy neutrinos scatter with the cosmic neutrino background through an ∼mev mediator. taking the density matrix approach, we develop a formalism to study the propagation of pev neutrinos in the presence of the new neutrino interaction. if the interaction is flavored such as the gauged lμ-lτ model we consider, the resonant collision may not suppress the pev neutrino flux completely. the new force mediator may also contribute to the number of effectively massless degrees of freedom in the early universe and change the diffusion time of neutrinos from the supernova core. astrophysical observations such as big bang nucleosynthesis and supernova cooling provide an interesting test for the explanation. | coherent propagation of pev neutrinos and the dip in the neutrino spectrum at icecube |
we present a new solution to the electroweak hierarchy problem. we introduce n copies of the standard model with varying values of the higgs mass parameter. this generically yields a sector whose weak scale is parametrically removed from the cutoff by a factor of 1 /√{n }. ensuring that reheating deposits a majority of the total energy density into this lightest sector requires a modification of the standard cosmological history, providing a powerful probe of the mechanism. current and near-future experiments can explore much of the natural parameter space. furthermore, supersymmetric completions that preserve grand unification predict superpartners with mass below mwmpl/mgut∼10 tev . | solving the hierarchy problem at reheating with a large number of degrees of freedom |
primordial black holes (pbhs) represent a natural candidate for one of the components of the dark matter (dm) in the universe. in this review, we shall discuss the basics of their formation, abundance and signatures. some of their characteristic signals are examined, such as the emission of particles due to hawking evaporation and the accretion of the surrounding matter, effects which could leave an impact in the evolution of the universe and the formation of structures. the most relevant probes capable of constraining their masses and population are discussed. | a brief review on primordial black holes as dark matter |
the core cosmology library (ccl) provides routines to compute basic cosmological observables to a high degree of accuracy, which have been verified with an extensive suite of validation tests. predictions are provided for many cosmological quantities, including distances, angular power spectra, correlation functions, halo bias, and the halo mass function through state-of-the-art modeling prescriptions available in the literature. fiducial specifications for the expected galaxy distributions for the large synoptic survey telescope (lsst) are also included, together with the capability of computing redshift distributions for a user-defined photometric redshift model. a rigorous validation procedure, based on comparisons between ccl and independent software packages, allows us to establish a well-defined numerical accuracy for each predicted quantity. as a result, predictions for correlation functions of galaxy clustering, galaxy-galaxy lensing, and cosmic shear are demonstrated to be within a fraction of the expected statistical uncertainty of the observables for the models and in the range of scales of interest to lsst. ccl is an open source software package written in c, with a python interface and publicly available at https://github.com/lsstdesc/ccl. | core cosmology library: precision cosmological predictions for lsst |
theories of dark energy and modified gravity can be strongly constrained by astrophysical or cosmological observations, as illustrated by the recent observation of the gravitational wave event gw170817 and of its electromagnetic counterpart grb 170817a, which showed that the speed of gravitational waves, cg , is the same as the speed of light, within deviations of order 10-15 . this observation implies severe restrictions on scalar-tensor theories, in particular theories whose action depends on second derivatives of a scalar field. working in the very general framework of degenerate higher-order scalar-tensor (dhost) theories, which encompass horndeski and beyond horndeski theories, we present the dhost theories that satisfy cg=c . we then examine, for these theories, the screening mechanism that suppresses scalar interactions on small scales, namely the vainshtein mechanism, and compute the corresponding gravitational laws for a nonrelativistic spherical body. we show that it can lead to a deviation from standard gravity inside matter, parametrized by three coefficients which satisfy a consistency relation and can be constrained by present and future astrophysical observations. | scalar-tensor theories and modified gravity in the wake of gw170817 |
primordial black holes (pbh) could be the cold dark matter of the universe. they could have arisen from large (order one) curvature fluctuations produced during inflation that reentered the horizon in the radiation era. at reentry, these fluctuations source gravitational waves (gw) via second order anisotropic stresses. these gw, together with those (possibly) sourced during inflation by the same mechanism responsible for the large curvature fluctuations, constitute a primordial stochastic gw background (sgwb) that unavoidably accompanies the pbh formation. we study how the amplitude and the range of frequencies of this signal depend on the statistics (gaussian versus χ2) of the primordial curvature fluctuations, and on the evolution of the pbh mass function due to accretion and merging. we then compare this signal with the sensitivity of present and future detectors, at pta and lisa scales. we find that this sgwb will help to probe, or strongly constrain, the early universe mechanism of pbh production. the comparison between the peak mass of the pbh distribution and the peak frequency of this sgwb will provide important information on the merging and accretion evolution of the pbh mass distribution from their formation to the present era. different assumptions on the statistics and on the pbh evolution also result in different amounts of cmb μ-distortions. therefore the above results can be complemented by the detection (or the absence) of μ-distortions with an experiment such as pixie. | gravitational wave signatures of inflationary models from primordial black hole dark matter |
the stochastic gravitational wave background (sgwb) is expected to be a key observable for gravitational wave (gw) interferometry. its detection will open a new window to early universe cosmology and to the astrophysics of compact objects. using a boltzmann approach, we study the angular anisotropies of the gw energy density, which is an important tool to disentangle the different cosmological and astrophysical contributions to the sgwb. anisotropies in the cosmological background are imprinted both at its production and by gw propagation through the large-scale scalar and tensor perturbations of the universe. the first contribution is not present in the cosmic microwave background radiation (as the universe is not transparent to photons before recombination), causing an order 1 dependence of the anisotropies on frequency. moreover, we provide a new method to characterize the cosmological sgwb through its possible deviation from gaussian statistics. in particular, the sgwb will become a new probe of the primordial non-gaussianity of the large-scale cosmological perturbations. | anisotropies and non-gaussianity of the cosmological gravitational wave background |
we present simulations from the new “figuring out gas & galaxies in enzo” (foggie) project. in contrast to most extant simulations of galaxy formation, which concentrate computational resources on galactic disks and spheroids with fluid and particle elements of fixed mass, the foggie simulations focus on extreme spatial and mass resolution in the circumgalactic medium (cgm) surrounding galaxies. using the enzo code and a new refinement scheme, foggie reaches spatial resolutions of 381 comoving h -1 pc and resolves extremely low masses (≲1-100 {{{m}}}⊙ ) out to 100 comoving h -1 kpc from the central halo. at these resolutions, cloud and filament-like structures giving rise to simulated absorption are smaller, and better resolved, than the same structures simulated with standard density-dependent refinement. most of the simulated absorption arises in identifiable and well-resolved structures with masses ≲104 {{{m}}}⊙ , well below the mass resolution of typical zoom simulations. however, integrated quantities such as mass surface density and ionic covering fractions change at only the ≲30% level as resolution is varied. these relatively small changes in projected quantities—even when the sizes and distribution of absorbing clouds change dramatically—indicate that commonly used observables provide only weak constraints on the physical structure of the underlying gas. comparing the simulated absorption features to the kodiaq (keck observatory database of ionized absorption toward quasars) survey of z ∼ 2-3.5 lyman limit systems, we show that high-resolution foggie runs better resolve the internal kinematic structure of detected absorption and better match the observed distribution of absorber properties. these results indicate that circumgalactic medium resolution is key in properly testing simulations of galaxy evolution with circumgalactic observations. | figuring out gas & galaxies in enzo (foggie). i. resolving simulated circumgalactic absorption at 2 ≤ z ≤ 2.5 |
we present the most comprehensive global fits to date of three supersymmetric models motivated by grand unification: the constrained minimal supersymmetric standard model (cmssm), and its non-universal higgs mass generalisations nuhm1 and nuhm2. we include likelihoods from a number of direct and indirect dark matter searches, a large collection of electroweak precision and flavour observables, direct searches for supersymmetry at lep and runs i and ii of the lhc, and constraints from higgs observables. our analysis improves on existing results not only in terms of the number of included observables, but also in the level of detail with which we treat them, our sampling techniques for scanning the parameter space, and our treatment of nuisance parameters. we show that stau co-annihilation is now ruled out in the cmssm at more than 95% confidence. stop co-annihilation turns out to be one of the most promising mechanisms for achieving an appropriate relic density of dark matter in all three models, whilst avoiding all other constraints. we find high-likelihood regions of parameter space featuring light stops and charginos, making them potentially detectable in the near future at the lhc. we also show that tonne-scale direct detection will play a largely complementary role, probing large parts of the remaining viable parameter space, including essentially all models with multi-tev neutralinos. | global fits of gut-scale susy models with gambit |
the initial data from the event horizon telescope (eht) on m 87* , the supermassive black hole at the center of the m87 galaxy, provide direct observational information on its mass, spin, and accretion disk properties. a combination of the eht data and other constraints provides evidence that m 87* has a mass ∼6.5 ×109 m⊙ . eht also inferred the dimensionless spin parameter |a*|≳0.5 from jet properties; a separate recent analysis using only the light from near m 87* as measured by the eht collaboration found |a*|=0.9 ±0.1 . these determinations disfavor ultralight bosons of mass μb∈(0.85 ,4.6 )×10-21 ev for spin-one bosons and μb∈(2.9 ,4.6 )×10-21 ev for spin-zero bosons, within the range considered for fuzzy dark matter, invoked to explain dark matter distribution on approximately kiloparsec scales. future observations of m 87* could be expected to strengthen our conclusions. | ultralight boson dark matter and event horizon telescope observations of m 87* |
energy conditions can play an important role in defining the cosmological evolution. specifically acceleration/deceleration of cosmic fluid, as well as the emergence of big rip singularities, can be related to the constraints imposed by the energy conditions. here we discuss this issue for f (r) gravity considering also conformal transformations. cosmological solutions and equations of state can be classified according to energy conditions. the qualitative change of some energy conditions when transformation from the jordan frame to the einstein frame done is also observed. | the role of energy conditions in f(r) cosmology |
axion-like early dark energy (ede) as an extension to $\lambda$cdm has been proposed as a possible solution to the 'hubble tension'. we revisit this model using a new cosmic microwave background (cmb) temperature and polarization likelihood constructed from the {\it planck} npipe data release. in a bayesian analysis, we find that the maximum fractional contribution of ede to the total energy density is $f_{\rm ede} < 0.061$ (without sh0es) over the redshift range $z\in[10^3,10^4]$ and that the hubble constant is constrained to lie within the range $ 66.9 < h_0 < 69.5$ km/s/mpc (both at 95 \% c.l.). the data therefore favour a model close to $\lambda$cdm, leaving a residual tension of $3.7\sigma$ with the sh$0$es cepheid-based measurement of $h_0$. a comparison with the likelihood profile shows that our conclusions are robust to prior-volume effects. our new cmb likelihood provides no evidence in favour of a significant ede component. | improved planck constraints on axion-like early dark energy as a resolution of the hubble tension |
i present a review of how late observations of supernovae, of the nebular phase, and much later of supernova remnants (snrs), and their analysis in 2023 made progress towards breakthroughs in supporting the jittering jets explosion mechanism (jjem) for core-collapse supernovae (ccsne) and in introducing the group of lonely white dwarf (wd) scenarios for type ia supernovae (sne ia). the new analyses of ccsn remnants (ccsnrs) reveal point-symmetric morphologies in a way unnoticed before in three ccsnrs. comparison to multipolar planetary nebulae that are shaped by jets suggests that jets exploded these ccsne, as predicted by the jjem, but incompatible with the prediction of the delayed neutrino explosion mechanism. the spherical morphology of the ejecta pa 30 of the historical type iax supernova (sn iax) of 1181 ad, which studies in 2023 revealed, is mostly compatible with the explosion of a lonely wd. namely, at the explosion time, there is only a wd, without any close companion, although the wd was formed via a close binary interaction, i.e., binary merger. an identification of point-symmetry in snr g1.9+0.3, a normal sn ia and the youngest sn in the galaxy, suggests an sn explosion of a lonely wd inside a planetary nebula (an snip). the group of lonely wd scenarios includes the core degenerate scenario and the double degenerate scenario with a merger to explosion delay (med) time. sn ia explosions of lonely wds are common, and might actually account for most (or even all) normal sne ia. | supernovae in 2023 (review): breakthroughs by late observations |
we revisit the one-loop corrections on cmb scale perturbations induced from small scale modes in single field models which undergo a phase of ultra slow-roll inflation. there were concerns that large loop corrections are against the notion of the decoupling of scales and they are cancelled out once the boundary terms are included in hamiltonian. we highlight that the non-linear coupling between the long and short modes and the modulation of the short mode power spectrum by the long mode are the key physical reasons behind the large loop corrections. in particular, in order for the modulation by the long mode to be significant there should be a strong scale-dependent enhancement in power spectrum of the short mode which is the hallmark of the usr inflation. we highlight the important roles played by the would-be decaying mode which were not taken into account properly in recent works claiming the loop cancellation. we confirm the original conclusion that the loop corrections are genuine and they can be dangerous for pbhs formation unless the transition to the final attractor phase is mild. | revisiting loop corrections in single field usr inflation |
single field models of inflation capable of producing primordial black holes usually require a significant departure from the standard, perturbative slow-roll regime. in fact, in many of these scenarios, the size of the slow-roll parameter |η | becomes larger than one during a short phase of inflationary evolution. in order to develop an analytical control on these systems, we explore the limit of |η | large, and promote 1 /|η | to a small quantity to be used for perturbative expansions. formulas simplify, and we obtain analytic expressions for the two and three point functions of curvature fluctuations, which share some of the features found in realistic inflationary models generating primordial black holes. we study one-loop corrections in this framework: we discuss criteria for adsorbing ultraviolet divergences into the available parameters, leaving log-enhanced infrared contributions of controllable size. | large |η | approach to single field inflation |
hot spots, or plasmoids, which form due to magnetic reconnection in current sheets, are conjectured to power frequent x-ray and near-infrared flares from sgr a*, the black hole in the center of our galaxy. it is unclear how, where, and when current sheets form in black hole accretion disks. we perform axisymmetric general-relativistic resistive magnetohydrodynamics simulations to model reconnection and plasmoid formation in a range of accretion flows. current sheets and plasmoids are ubiquitous features that form regardless of the initial magnetic field in the disk, the magnetization in the quasisteady-state phase of accretion, and the spin of the black hole. within 10 schwarzschild radii from the event horizon, we observe plasmoids forming, after which they can merge, grow to macroscopic scales of the order of a few schwarzschild radii, and are ultimately advected along the jet's sheath or into the disk. large plasmoids are energized to relativistic temperatures via reconnection and contribute to the jet's limb brightening. we find that only hot spots forming in magnetically arrested disks can potentially explain the energetics of sgr a* flares. the flare period is determined by the reconnection rate, which we find to be between $0.01c$ and $0.03c$ in all cases, consistent with studies of reconnection in isolated harris-type current sheets. we quantify magnetic dissipation and nonideal electric fields, which can efficiently inject nonthermal particles. we show that explicit resistivity allows for converged numerical solutions, such that the electromagnetic energy evolution and dissipation become independent of the grid scale for the extreme resolutions considered here. | magnetic reconnection and hot spot formation in black hole accretion disks |
strongly-coupled theories at the tev can naturally drive a long period of supercooling in the early universe. trapped into the deconfined phase, the universe could inflate and cool down till the temperature reaches the qcd strong scale. we show how at these low temperatures qcd effects are important and could trigger the exit from the long supercooling era. we also study the implications on relic abundances. in particular, the latent heat released at the end of supercooling could be the reason for the similarities between dark matter and baryon energy densities. the axion abundance could also be significantly affected, allowing for larger values of the axion decay constant. finally, we discuss how a long supercooling epoch could lead to an enhanced gravitational wave signal. | the supercooled universe |
many attempts to solve the hubble tension with extended cosmological models combine an enhanced relic radiation density, acting at the level of background cosmology, with new physical ingredients affecting the evolution of cosmological perturbations. several authors have pointed out the ability of combined baryon acoustic oscillation (bao) and big bang nucleosynthesis (bbn) data to probe the background cosmological history independently of both cmb maps and supernovae data. using state-of-the-art assumptions on bbn, we confirm that combined bao, deuterium, and helium data are in tension with the sh0es measurements under the λcdm assumption at the 3.2σ level, while being in close agreement with the cmb value. we subsequently show that floating the radiation density parameter neff only reduces the tension down to the 2.6σ level. this conclusion, totally independent of any cmb data, shows that a high neff accounting for extra relics (either free-streaming or self-interacting) does not provide an obvious solution to the crisis, not even at the level of background cosmology. to circumvent this strong bound, (i) the extra radiation has to be generated after bbn to avoid helium bounds, and (ii) additional ingredients have to be invoked at the level of perturbations to reconcile this extra radiation with cmb and lss data. | the bao+bbn take on the hubble tension |
we study the existence and stability of classical de sitter solutions of type ii supergravities with parallel dp-branes and orientifold op-planes. together with the dilaton and volume scalar fields, we consider a third one that distinguishes between parallel and transverse directions to the dp/op. we derive the complete scalar potential for these three fields. this formalism allows us to reproduce known constraints obtained in 10d, and to derive new ones. specifying to group manifolds with constant fluxes, we exclude a large region of parameter space, forbidding de sitter solutions on nilmanifolds, semi-simple group manifolds, and some solvmanifolds. in the small remaining region, we identify a stability island, where the three scalars could be stabilized in any de sitter solution. we discuss these results in the swampland context. | new constraints on classical de sitter: flirting with the swampland |
we first show that the effective nonrelativistic theory of gravitationally interacting, massive integer-spin fields (spin-0, 1, and 2 in particular) is described by a 2 s +1 component schrödinger-poisson action, where s is the spin of the field. we then construct s +1 distinct, gravitationally supported solitons in this nonrelativistic theory from identically polarized plane waves. such solitons are extremally polarized, with macroscopically large spin, but no orbital angular momentum. these s +1 solitons form a basis set, out of which partially polarized solitons can be constructed. all such solitons are ground states, have a spherically symmetric energy density but not field configurations. we discuss how solitons in higher-spin fields can be distinguished from scalar solitons, and potential gravitational and nongravitational probes of them. | polarized solitons in higher-spin wave dark matter |
primordial black hole (pbh) fluctuations can induce a stochastic gravitational wave background at second order, and since this procedure is sensitive to the underlying gravitational theory it can be used as a novel tool to test general relativity and extract constraints on possible modified gravity deviations. we apply this formalism in the framework of f(t) gravity, considering three viable mono-parametric models. in particular, we investigate the induced modifications at the level of the gravitational-wave source, which is encoded in terms of the power spectrum of the pbh gravitational potential, as well as at the level of their propagation, described in terms of the green function which quantifies the propagator of the tensor perturbations. we find that, within the observationally allowed range of the f(t) model-parameters, the obtained deviations from general relativity, both at the levels of source and propagation, are practically negligible. hence, we conclude that realistic and viable f(t) theories can safely pass the primordial black hole constraints, which may offer an additional argument in their favor. | no constraints for f(t) gravity from gravitational waves induced from primordial black hole fluctuations |
models that produce axionlike particles (alps) after cosmological inflation due to spontaneous u (1 ) symmetry breaking also produce cosmic-string networks. those axionic strings lose energy through gravitational-wave emission during the whole cosmological history, generating a stochastic background of gravitational waves that spans many decades in frequency. we can therefore constrain the axion decay constant and axion mass from limits on the gravitational-wave spectrum and compatibility with dark matter abundance as well as dark radiation. we derive such limits from analyzing the most recent nanograv data from pulsar timing arrays (ptas). the limits are similar to the neff bounds on dark radiation for alp masses ma≲10-22 ev . on the other hand, for heavy alps with ma≳0.1 gev and ndw≠1 , new regions of parameter space can be probed by pta data due to the dominant domain-wall contribution to the gravitational-wave background. | constraining postinflationary axions with pulsar timing arrays |
i present a fast python tool, spectres, for carrying out the resampling of spectral flux densities and their associated uncertainties onto different wavelength grids. the function works with any grid of wavelength values, including non-uniform sampling, and preserves the integrated flux. this may be of use for binning data to increase the signal to noise ratio, obtaining synthetic photometry, or resampling model spectra to match the sampling of observed data for spectral energy distribution fitting. the function can be downloaded from https://www.github.com/accarnall/spectres. | spectres: a fast spectral resampling tool in python |
we show that the well-known problem of frame dependence and violation of local lorentz invariance in the usual formulation of f(t) gravity is a consequence of neglecting the role of spin connection. we re-formulate f(t) gravity starting from, instead of the ‘pure tetrad’ teleparallel gravity, the covariant teleparallel gravity, using both the tetrad and the spin connection as dynamical variables, resulting in a fully covariant, consistent, and frame-independent version of f(t) gravity, which does not suffer from the notorious problems of the usual, pure tetrad, f(t) theory. we present the method to extract solutions for the most physically important cases, such as the minkowski, the friedmann-robertson-walker (frw) and the spherically symmetric ones. we show that in covariant f(t) gravity we are allowed to use an arbitrary tetrad in an arbitrary coordinate system along with the corresponding spin connection, resulting always in the same physically relevant field equations. | the covariant formulation of f(t) gravity |
we present a theoretical analysis of some unexplored aspects of relaxed bose-einstein condensate dark matter (becdm) haloes. this type of ultralight bosonic scalar field dark matter is a viable alternative to the standard cold dark matter (cdm) paradigm, as it makes the same large-scale predictions as cdm and potentially overcomes cdm's small-scale problems via a galaxy-scale de broglie wavelength. we simulate becdm halo formation through mergers, evolved under the schrödinger-poisson equations. the formed haloes consist of a soliton core supported against gravitational collapse by the quantum pressure tensor and an asymptotic r-3 nfw-like profile. we find a fundamental relation of the core-to-halo mass with the dimensionless invariant ξ ≡ |e|/m3/(gm/ℏ)2 or mc/m ≃ 2.6ξ1/3, linking the soliton to global halo properties. for r ≥ 3.5 rc core radii, we find equipartition between potential, classical kinetic and quantum gradient energies. the haloes also exhibit a conspicuous turbulent behaviour driven by the continuous reconnection of vortex lines due to wave interference. we analyse the turbulence 1d velocity power spectrum and find a k-1.1 power law. this suggests that the vorticity in becdm haloes is homogeneous, similar to thermally-driven counterflow bec systems from condensed matter physics, in contrast to a k-5/3 kolmogorov power law seen in mechanically-driven quantum systems. the mode where the power spectrum peaks is approximately the soliton width, implying that the soliton-sized granules carry most of the turbulent energy in becdm haloes. | galaxy formation with becdm - i. turbulence and relaxation of idealized haloes |
the stochastic gravitational wave background (sgwb) recently detected by the pta collaborations could be the gravitational waves (gws) induced by curvature perturbations. however, primordial black holes (pbhs) might be overproduced if the sgwb is explained by the gws induced by the curvature perturbations that follow the gaussian distribution. this motivates models associated with the non-gaussianity of the curvature perturbations that suppress the pbh production rate. in this work, we show that the axion curvaton model can produce the curvature perturbations that induce gws for the detected sgwb while preventing the pbh overproduction with the non-gaussianity. | axion curvaton model for the gravitational waves observed by pulsar timing arrays |
the total mass of a galaxy cluster is one of its most fundamental properties. together with the redshift, the mass links observation and theory, allowing us to use the cluster population to test models of structure formation and to constrain cosmological parameters. building on the rich heritage from x-ray surveys, new results from sunyaev-zeldovich and optical surveys have stimulated a resurgence of interest in cluster cosmology. these studies have generally found fewer clusters than predicted by the baseline planck λcdm model, prompting a renewed effort on the part of the community to obtain a definitive measure of the true cluster mass scale. here we review recent progress on this front. our theoretical understanding continues to advance, with numerical simulations being the cornerstone of this effort. on the observational side, new, sophisticated techniques are being deployed in individual mass measurements and to account for selection biases in cluster surveys. we summarise the state of the art in cluster mass estimation methods and the systematic uncertainties and biases inherent in each approach, which are now well identified and understood, and explore how current uncertainties propagate into the cosmological parameter analysis. we discuss the prospects for improvements to the measurement of the mass scale using upcoming multi-wavelength data, and the future use of the cluster population as a cosmological probe. | the galaxy cluster mass scale and its impact on cosmological constraints from the cluster population |
we discuss the nonlinear corrections entering in the calculation of the primordial black hole abundance from the nonlinear radiation transfer function and the determination of the true physical horizon crossing. we show that the current standard techniques to calculate the abundance of primordial black holes suffer from uncertainties and argue that the primordial black hole abundance may be much smaller than what routinely considered. this would imply, among other consequences, that the interpretation of the recent pulsar timing arrays data from scalar-induced gravitational waves may not be ruled out because of an overproduction of primordial black holes. | how well do we know the primordial black hole abundance: the crucial role of nonlinearities when approaching the horizon |
on a time scale of years to decades, gravitational wave (gw) astronomy will become a reality. low frequency (nanohz) gws are detectable through long-term timing observations of the most stable pulsars. radio observatories worldwide are currently carrying out observing programmes to detect gws, with data sets being shared through the international pulsar timing array project. one of the most likely sources of low frequency gws are supermassive black hole binaries (smbhbs), detectable as a background due to a large number of binaries, or as continuous or burst emission from individual sources. no gw signal has yet been detected, but stringent constraints are already being placed on galaxy evolution models. the ska will bring this research to fruition. in this chapter, we describe how timing observations using ska1 will contribute to detecting gws, or can confirm a detection if a first signal already has been identified when ska1 commences observations. we describe how ska observations will identify the source(s) of a gw signal, search for anisotropies in the background, improve models of galaxy evolution, test theories of gravity, and characterise the early inspiral phase of a smbhb system. we describe the impact of the large number of millisecond pulsars to be discovered by the ska; and the observing cadence, observation durations, and instrumentation required to reach the necessary sensitivity. we describe the noise processes that will influence the achievable precision with the ska. we assume a long-term timing programme using the ska1-mid array and consider the implications of modifications to the current design. we describe the possible benefits from observations using ska1-low. finally, we describe gw detection prospects with ska1 and ska2, and end with a description of the expectations of gw astronomy. | gravitational wave astronomy with the ska |
the broadening of atomic emission lines by high-velocity motion of gas near accreting supermassive black holes is an observational hallmark of quasars1. observations of broad emission lines could potentially constrain the mechanism for transporting gas inwards through accretion disks or outwards through winds2. the size of regions for which broad emission lines are observed (broad-line regions) has been estimated by measuring the delay in light travel time between the variable brightness of the accretion disk continuum and the emission lines3—a method known as reverberation mapping. in some models the emission lines arise from a continuous outflow4, whereas in others they arise from orbiting gas clouds5. directly imaging such regions has not hitherto been possible because of their small angular size (less than 10-4 arcseconds3,6). here we report a spatial offset (with a spatial resolution of 10-5 arcseconds, or about 0.03 parsecs for a distance of 550 million parsecs) between the red and blue photo-centres of the broad paschen-α line of the quasar 3c 273 perpendicular to the direction of its radio jet. this spatial offset corresponds to a gradient in the velocity of the gas and thus implies that the gas is orbiting the central supermassive black hole. the data are well fitted by a broad-line-region model of a thick disk of gravitationally bound material orbiting a black hole of 3 × 108 solar masses. we infer a disk radius of 150 light days; a radius of 100-400 light days was found previously using reverberation mapping7-9. the rotation axis of the disk aligns in inclination and position angle with the radio jet. our results support the methods that are often used to estimate the masses of accreting supermassive black holes and to study their evolution over cosmic time. | spatially resolved rotation of the broad-line region of a quasar at sub-parsec scale |
we investigate the prospects of detecting gravitational waves from coalescing massive black hole binaries in the universe with the tianqin observatory, a space-based gravitational wave interferometer proposed to be launched in the 2030s. to frame the scientific scope of the mission, in this paper, we carry out a preliminary estimation of the signal-to-noise ratio, detection rate, and parameter estimation precision of massive black hole binaries detectable by tianqin. in order to make our results as robust as possible, we consider several models of the growth history of massive black holes, exploring the effect of some key astrophysical prescriptions as well as the impact of the employed computational methods. in the most optimistic model, tianqin can detect as many as approximately 60 mergers per year. if tianqin detects a merger at redshift of 15, it will be capable of estimating its luminosity distance to within an accuracy of 10%; for a nearby event at redshift approximately 2, tianqin can issue early warnings 24 hours before coalescence, with a timing accuracy of around three hours and a sky localization ability of approximately 80 deg2 , thus enabling multimessenger observations. | science with the tianqin observatory: preliminary results on massive black hole binaries |
code investigating galaxy emission (cigale) is a powerful multiwavelength spectral energy distribution (sed) fitting code for extragalactic studies. however, the current version of cigale is not able to fit x-ray data, which often provide unique insights into active galactic nucleus (agn) intrinsic power. we develop a new x-ray module for cigale, allowing it to fit seds from the x-ray to infrared (ir). we also improve the agn fitting of cigale from uv-to-ir wavelengths. we implement a modern clumpy two-phase torus model, skirtor. to account for moderately extincted type 1 agns, we implement polar-dust extinction. we publicly release the source code (named 'x-cigale'). we test x-cigale with x-ray detected agns in sdss, cosmos, and akari-nep. the fitting quality (as indicated by reduced χ2) is good in general, indicating that x-cigale is capable of modelling the observed sed from x-ray to ir. we discuss constrainability and degeneracy of model parameters in the fitting of akari-nep, for which excellent mid-ir photometric coverage is available. we also test fitting a sample of akari-nep galaxies for which only x-ray upper limits are available from chandra observations, and find that the upper limit can effectively constrain the agn sed contribution for some systems. finally, using x-cigale, we assess the ability of athena to constrain the agn activity in future extragalactic studies. | x-cigale: fitting agn/galaxy seds from x-ray to infrared |
we present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts. in the process, we establish a simple way of comparing such surveys with optical galaxy redshift surveys. we explore a wide range of experimental configurations and assess how well a number of cosmological observables (the expansion rate, growth rate, and angular diameter distance) and parameters (the densities of dark energy and dark matter, spatial curvature, the dark energy equation of state, etc.) will be measured by an extensive roster of upcoming experiments. a number of potential contaminants and systematic effects are also studied in detail. the overall picture is encouraging—if autocorrelation calibration can be controlled to a sufficient level, phase i of the square kilometre array should be able to constrain the dark energy equation of state about as well as a detf stage iv galaxy redshift survey like euclid, in roughly the same time frame. | late-time cosmology with 21 cm intensity mapping experiments |
we study a model of inflation in which a scalar field χ is non-minimally coupled to starobinsky's r2 gravity. after transforming it to the einstein frame, a new scalar field, the scalaron phi, will appear and couple to χ with a nontrivial field metric, while χ acquires a positive mass via the non-minimal coupling. initially inflation occurs along the phi direction with χ trapped near its origin by this induced mass. after phi crosses a critical value, it starts rolling down rapidly and proceeds to damped oscillations around an effective local minimum determined by the value of χ, while inflation still continues, driven by the χ field at this second stage where the effect of the non-minimal coupling becomes negligible. the presence of the damped oscillations during the transition from the first to second stage of inflation causes enhancement and oscillation features in the power spectrum of the curvature perturbation. assuming that the oscillations may be treated perturbatively, we calculate these features by using the δ n formalism, and discuss its observational implications to large scale cmb anomalies or primordial black hole formation, depending on the scale of the features. | scalaron from r2-gravity as a heavy field |
we consider the cosmology derived from f( t, b) gravity where t is the torsion scalar and b=2/epartial _{μ }(e t^{μ }) a boundary term. in particular we discuss how it is possible to recover, under the same standard, the teleparallel f( t) gravity, the curvature f( r) gravity, and the teleparallel-curvature f( r, t) gravity, which are particular cases of f( t, b). we adopt the noether symmetry approach to study the related dynamical systems and to find cosmological solutions. | noether symmetry approach in f( t, b) teleparallel cosmology |
we present the data and initial results from the first pilot survey of the evolutionary map of the universe (emu), observed at 944 mhz with the australian square kilometre array pathfinder (askap) telescope. the survey covers $270 deg^2$ of an area covered by the dark energy survey, reaching a depth of 25-30 $μjy beam^{-1}$ rms at a spatial resolution of $∼$ 11-18 arcsec, resulting in a catalogue of $∼$ 220 000 sources, of which $∼$ 180 000 are single-component sources. here we present the catalogue of single-component sources, together with (where available) optical and infrared cross-identifications, classifications, and redshifts. this survey explores a new region of parameter space compared to previous surveys. specifically, the emu pilot survey has a high density of sources, and also a high sensitivity to low surface brightness emission. these properties result in the detection of types of sources that were rarely seen in or absent from previous surveys. we present some of these new results here. | the evolutionary map of the universe pilot survey |
discovery of pulsars is one of the main goals for large radio telescopes. the five-hundred-meter aperture spherical radio telescope (fast), that incorporates an l-band 19-beam receiver with a system temperature of about 20 k, is the most sensitive radio telescope utilized for discovering pulsars. we designed the snapshot observation mode for a fast key science project, the galactic plane pulsar snapshot (gpps) survey, in which every four nearby pointings can observe a cover of a sky patch of 0.1575 square degrees through beam-switching of the l-band 19-beam receiver. the integration time for each pointing is 300 seconds so that the gpps observations for a cover can be made in 21 minutes. the goal of the gpps survey is to discover pulsars within the galactic latitude of ± 10° from the galactic plane, and the highest priority is given to the inner galaxy within ± 5°. up to now, the gpps survey has discovered 201 pulsars, including currently the faintest pulsars which cannot be detected by other telescopes, pulsars with extremely high dispersion measures (dms) which challenge the currently widely used models for the galactic electron density distribution, pulsars coincident with supernova remnants, 40 millisecond pulsars, 16 binary pulsars, some nulling and mode-changing pulsars and rotating radio transients (rrats). the follow-up observations for confirmation of new pulsars have polarization-signals recorded for polarization profiles of the pulsars. re-detection of previously known pulsars in the survey data also leads to significant improvements in parameters for 64 pulsars. the gpps survey discoveries are published and will be updated at http://zmtt.bao.ac.cn/gpps/. ⋆news and views on this paper | the fast galactic plane pulsar snapshot survey: i. project design and pulsar discoveries |
we define compactness of a gravitational lens as the scaled closest distance of approach (i.e., $r_0/m$) of the null geodesic giving rise to an image. we model forty supermassive dark objects as schwarzschild lenses and compute compactness of lenses (determined by the formation of the first order relativistic image). we then obtain a novel formula for the compactness of a lens as a function of mass to the distance ratio ($m/d_d$) and the ratio of lens-source to the observer-source distances ($d_{ds}/d_s$). this formula yields an interesting result: just an observation of a relativistic image would give an incredibly accurate upper bound to the compactness of the lens without having any knowledge of mass of the lens, angular source position, and observer-source and lens-source distances. similarly, we show that the observation of the second order relativistic image would give a lower value of upper bound to the compactness. these results, though obtained for supermassive dark objects at galactic centers, are valid for any object compact enough to give rise to relativistic images. | compactness of supermassive dark objects at galactic centers |
we compute the spherically averaged power spectrum from four seasons of data obtained for the epoch of reionization (eor) project observed with the murchison widefield array (mwa). we measure the eor power spectrum over k = 0.07-3.0 h mpc-1 at redshifts z = 6.5-8.7. the largest aggregation of 110 h on eor0 high band (3340 observations), yields a lowest measurement of (43 mk)2 = 1.8 × 103 mk2 at k = 0.14 h mpc-1 and z = 6.5 (2σ thermal noise plus sample variance). using the real-time system to calibrate and the chips pipeline to estimate power spectra, we select the best observations from the central five pointings within the 2013-2016 observing seasons, observing three independent fields and in two frequency bands. this yields 13 591 2-min snapshots (453 h), based on a quality assurance metric that measures ionospheric activity. we perform another cut to remove poorly calibrated data, based on power in the foreground-dominated and eor-dominated regions of the two-dimensional power spectrum, reducing the set to 12 569 observations (419 h). these data are processed in groups of 20 observations, to retain the capacity to identify poor data, and used to analyse the evolution and structure of the data over field, frequency, and data quality. we subsequently choose the cleanest 8935 observations (298 h of data) to form integrated power spectra over the different fields, pointings, and redshift ranges. | deep multiredshift limits on epoch of reionization 21 cm power spectra from four seasons of murchison widefield array observations |
anti-de sitter (ads) vacua, being theoretically important, might have an unexpected impact on the observable universe. we find that in early dark energy (ede) scenarios the existence of ads vacua around recombination can effectively lift the cmb-inferred h0 value. as an example, we study a phenomenological ede model with an ads phase starting at the redshift z ∼2000 and ending shortly after recombination (hereafter the universe will settle down in a λ >0 phase until now), and obtain a best-fit h0=72.74 km /s /mpc without degrading the cmb fit compared with the standard λ cdm model. | is the hubble tension a hint of ads phase around recombination? |
we search for isotropic stochastic gravitational-wave background (sgwb) in the international pulsar timing array second data release. by modeling the sgwb as a power-law, we find very strong bayesian evidence for a common-spectrum process, and further this process has scalar transverse (st) correlations allowed in general metric theory of gravity as the bayes factor in favor of the st-correlated process versus the spatially uncorrelated common-spectrum process is 30 ± 2. the median and the 90% equal-tail amplitudes of st mode are ${{ \mathcal a }}_{\mathrm{st}}={1.29}_{-0.44}^{+0.51}\times {10}^{-15}$ , or equivalently the energy density parameter per logarithm frequency is ${{\rm{\omega }}}_{\mathrm{gw}}^{\mathrm{st}}={2.31}_{-1.30}^{+2.19}\times {10}^{-9}$ , at frequency of 1 year-1. however, we do not find any statistically significant evidence for the tensor transverse (tt) mode and then place the 95% upper limits as ${{ \mathcal a }}_{\mathrm{tt}}\lt 3.95\times {10}^{-15}$ , or equivalently ${{\rm{\omega }}}_{\mathrm{gw}}^{\mathrm{tt}}\lt 2.16\times {10}^{-9}$ , at frequency of 1 year-1. | searching for isotropic stochastic gravitational-wave background in the international pulsar timing array second data release |
we construct an analytically solvable simplified model that captures the essential features for primordial black hole (pbh) production in most models of single-field inflation. the construction makes use of the wands duality between the constant-roll (or slow-roll) and the preceding ultra-slow-roll phases and can be realized by a simple inflaton potential of two joined parabolas. within this framework, it is possible to formulate explicit inflationary scenarios consistent with the cmb observations and copious production of pbhs of arbitrary mass. we quantify the variability of the shape of the peak in the curvature power spectrum in different inflationary scenarios and discuss its implications for probing pbhs with scalar-induced gravitational wave backgrounds. we find that the cobe/firas μ-distortion constraints exclude the production of pbhs heavier than 104 m ⊙ in single-field inflation. | anatomy of single-field inflationary models for primordial black holes |
we perform an ensemble of n-body simulations with 20483 particles for 101 flat wcdm cosmological models sampled based on a maximin distance sliced latin hypercube design. by using the halo catalogs extracted at multiple redshifts in the range of z = [0,1.48], we develop dark emulator, which enables fast and accurate computations of the halo mass function, halo-matter cross-correlation, and halo autocorrelation as a function of halo masses, redshift, separations, and cosmological models based on principal component analysis and gaussian process regression for the large-dimensional input and output data vector. we assess the performance of the emulator using a validation set of n-body simulations that are not used in training the emulator. we show that, for typical halos hosting cmass galaxies in the sloan digital sky survey, the emulator predicts the halo-matter cross-correlation, relevant for galaxy-galaxy weak lensing, with an accuracy better than 2% and the halo autocorrelation, relevant for galaxy clustering correlation, with an accuracy better than 4%. we give several demonstrations of the emulator. it can be used to study properties of halo mass density profiles such as the concentration-mass relation and splashback radius for different cosmologies. the emulator outputs can be combined with an analytical prescription of halo-galaxy connection, such as the halo occupation distribution at the equation level, instead of using the mock catalogs to make accurate predictions of galaxy clustering statistics, such as galaxy-galaxy weak lensing and the projected correlation function for any model within the wcdm cosmologies, in a few cpu seconds. | dark quest. i. fast and accurate emulation of halo clustering statistics and its application to galaxy clustering |
we use a new and statistically powerful planck likelihood to show that the planck temperature and polarization spectra are consistent with a spatially flat universe, in contrast to recent claims in the literature. when combined with other astrophysical data, particularly geometrical measurements of baryon acoustic oscillations, our likelihood constrains the universe to be spatially flat to extremely high precision. we deduce a curvature density parameter ωk = 0.0004 ± 0.0018 in good agreement with the 2018 results of the planck team. in the context of inflationary cosmology, the observations offer strong support for models of inflation with a large number of e-foldings and disfavour models of incomplete inflation. | the evidence for a spatially flat universe |
we interpret the recent nanograv results in terms of a stochastic gravitational wave background from metastable cosmic strings. the observed amplitude of a stochastic signal can be translated into a range for the cosmic string tension and the mass of magnetic monopoles arising in theories of grand unification. in a sizable part of the parameter space, this interpretation predicts a large stochastic gravitational wave signal in the frequency band of ground-based interferometers, which can be probed in the very near future. we confront these results with predictions from successful inflation, leptogenesis and dark matter from the spontaneous breaking of a gauged b-l symmetry. | from nanograv to ligo with metastable cosmic strings |
fast radio bursts (frbs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances1-3. it has long been speculated that magnetars are the engine powering repeating bursts from frb sources4-13, but no convincing evidence has been collected so far14. recently, the galactic magnetar srg 1935+2154 entered an active phase by emitting intense soft γ-ray bursts15. one frb-like event with two peaks (frb 200428) and a luminosity slightly lower than the faintest extragalactic frbs was detected from the source, in association with a soft γ-ray/hard-x-ray flare18-21. here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-x-ray) data. during the third session, 29 soft-γ-ray repeater (sgr) bursts were detected in γ-ray energies. throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of sgr bursts, but unfortunately we were not observing when the frb was detected. the non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of frb 200428. our results suggest that frb-sgr burst associations are rare. frbs may be highly relativistic and geometrically beamed, or frb-like events associated with sgr bursts may have narrow spectra and characteristic frequencies outside the observed band. it is also possible that the physical conditions required to achieve coherent radiation in sgr bursts are difficult to satisfy, and that only under extreme conditions could an frb be associated with an sgr burst. | no pulsed radio emission during a bursting phase of a galactic magnetar |
we present the grackle chemistry and cooling library for astrophysical simulations and models. grackle provides a treatment of non-equilibrium primordial chemistry and cooling for h, d and he species, including h2 formation on dust grains; tabulated primordial and metal cooling; multiple ultraviolet background models; and support for radiation transfer and arbitrary heat sources. the library has an easily implementable interface for simulation codes written in c, c++ and fortran as well as a python interface with added convenience functions for semi-analytical models. as an open-source project, grackle provides a community resource for accessing and disseminating astrochemical data and numerical methods. we present the full details of the core functionality, the simulation and python interfaces, testing infrastructure, performance and range of applicability. grackle is a fully open-source project and new contributions are welcome. | grackle: a chemistry and cooling library for astrophysics |
large, nonstandard neutrino self-interactions have been shown to resolve the ∼4 σ tension in hubble constant measurements and a milder tension in the amplitude of matter fluctuations. we demonstrate that interactions of the necessary size imply the existence of a force carrier with a large neutrino coupling (>10-4 ) and mass in the kev-100 mev range. this mediator is subject to stringent cosmological and laboratory bounds, and we find that nearly all realizations of such a particle are excluded by existing data unless it carries spin 0 and couples almost exclusively to τ -flavored neutrinos. furthermore, we find that the light neutrinos must be majorana particles, and that a uv-complete model requires a nonminimal mechanism to simultaneously generate neutrino masses and appreciable self-interactions. | constraining the self-interacting neutrino interpretation of the hubble tension |
in the last fifteen years radio detection made it back to the list of promising techniques for extensive air showers, firstly, due to the installation and successful operation of digital radio experiments and, secondly, due to the quantitative understanding of the radio emission from atmospheric particle cascades. the radio technique has an energy threshold of about 100 pev, which coincides with the energy at which a transition from the highest-energy galactic sources to the even more energetic extragalactic cosmic rays is assumed. thus, radio detectors are particularly useful to study the highest-energy galactic particles and ultra-high-energy extragalactic particles of all types. recent measurements by various antenna arrays like lopes, codalema, aera, lofar, tunka-rex, and others have shown that radio measurements can compete in precision with other established techniques, in particular for the arrival direction, the energy, and the position of the shower maximum, which is one of the best estimators for the composition of the primary cosmic rays. the scientific potential of the radio technique seems to be maximum in combination with particle detectors, because this combination of complementary detectors can significantly increase the total accuracy for air-shower measurements. this increase in accuracy is crucial for a better separation of different primary particles, like gamma-ray photons, neutrinos, or different types of nuclei, because showers initiated by these particles differ in average depth of the shower maximum and in the ratio between the amplitude of the radio signal and the number of muons. in addition to air-shower measurements, the radio technique can be used to measure particle cascades in dense media, which is a promising technique for detection of ultra-high-energy neutrinos. several pioneering experiments like ara, arianna, and anita are currently searching for the radio emission by neutrino-induced particle cascades in ice. in the next years these two sub-fields of radio detection of cascades in air and in dense media will likely merge, because several future projects aim at the simultaneous detection of both, high-energy cosmic-rays and neutrinos. ska will search for neutrino and cosmic-ray initiated cascades in the lunar regolith and simultaneously provide unprecedented detail for air-shower measurements. moreover, detectors with huge exposure like grand, sword or eva are being considered to study the highest energy cosmic rays and neutrinos. this review provides an introduction to the physics of radio emission by particle cascades, an overview on the various experiments and their instrumental properties, and a summary of methods for reconstructing the most important air-shower properties from radio measurements. finally, potential applications of the radio technique in high-energy astroparticle physics are discussed. | radio detection of cosmic-ray air showers and high-energy neutrinos |
recent astrophysical transient swift j1913.1+1946 is possibly associated with the gamma-ray burst grb 221009a at the redshift $z ≈ 0.151$. the transient was accompanied by very high-energy gamma rays up to 18 tev observed by lhaaso and a photon-like air shower of 251 tev detected by carpet-2. these energetic gamma rays cannot reach us from the claimed distance of the source because of the pair production on cosmic background radiation. if the identification and redshift measurements are correct, one would require new physics to explain the data. one possibility invokes axion-like particles (alps) which mix with photons but do not attenuate on the background radiation. here we explore the alp parameter space and find that the alp-photon mixing in the milky way, and not in the intergalactic space, may help to explain the observations. however, given the low galactic latitude of the event, misidentification with a galactic transient remains an undiscarded explanation. | parameters of axion-like particles required to explain high-energy photons from grb 221009a |
massive spinning particles acquire helicity-dependent chemical potentials during the inflation from axion-type couplings. such spinning fields can mediate sizable inflaton correlators which we call the helical inflation correlators. helical inflaton correlators are approximately scale invariant, ds boost breaking, parity violating, and are promising observables of cosmological collider physics. in this work, we present complete and analytical results for 4-point helical inflation correlators with tree-level exchanges of massive spinning particles, including both the smooth background and the oscillatory signals. we compute the bulk schwinger-keldysh integrals in two independent ways, including the partial mellin-barnes representation and solving bootstrap equations. we also present new closed-form analytical results for 3-point functions with massive scalar or helical spinning exchanges. the analytical results allow us to concretely and efficiently explore the phenomenological consequences of helicity-dependent chemical potentials. in particular, we show that the chemical potential can exponentially enhance oscillatory signals of both local and nonlocal types, but only affects the background in a rather mild way. our results extend the de sitter bootstrap program to include nonperturbative breaking of de sitter boosts. our results also explicitly verify the recently proposed cutting rule for cosmological collider signals. | helical inflation correlators: partial mellin-barnes and bootstrap equations |
we present lenstronomy, a multi-purpose open-source gravitational lens modelling pythonpackage. lenstronomy is able to reconstruct the lens mass and surface brightness distributions of strong lensing systems using forward modelling. lenstronomy supports a wide range of analytic lens and light models in arbitrary combination. the software is also able to reconstruct complex extended sources (birrer et. al 2015) as well as being able to model point sources. we designed lenstronomy to be stable, flexible and numerically accurate, with a clear user interface that could be deployed across different platforms. throughout its development, we have actively used lenstronomy to make several measurements including deriving constraints on dark matter properties in strong lenses, measuring the expansion history of the universe with time-delay cosmography, measuring cosmic shear with einstein rings and decomposing quasar and host galaxy light. the software is distributed under the mit license. the documentation, starter guide, example notebooks, source code and installation guidelines can be found at https://lenstronomy.readthedocs.io. | lenstronomy: multi-purpose gravitational lens modelling software package |
now that conventional weakly interacting massive particle (wimp) dark matter searches are approaching the neutrino floor, there has been a resurgence of interest in detectors with sensitivity to nuclear recoil directions. a large-scale directional detector is attractive in that it would have sensitivity below the neutrino floor, be capable of unambiguously establishing the galactic origin of a purported dark matter signal, and could serve a dual purpose as a neutrino observatory. we present the first detailed analysis of a 1000 m$^3$-scale detector capable of measuring a directional nuclear recoil signal at low energies. we propose a modular and multi-site observatory consisting of time projection chambers (tpcs) filled with helium and sf$_6$ at atmospheric pressure. depending on the tpc readout technology, 10-20 helium recoils above 6 kevr or only 3-4 recoils above 20 kevr would suffice to distinguish a 10 gev wimp signal from the solar neutrino background. high-resolution charge readout also enables powerful electron background rejection capabilities well below 10 kev. we detail background and site requirements at the 1000 m$^3$-scale, and identify materials that require improved radiopurity. the final experiment, which we name cygnus-1000, will be able to observe 10-40 neutrinos from the sun, depending on the final energy threshold. with the same exposure, the sensitivity to spin independent cross sections will extend into presently unexplored sub-10 gev parameter space. for spin dependent interactions, already a 10 m$^3$-scale experiment could compete with upcoming generation-two detectors, but cygnus-1000 would improve upon this considerably. larger volumes would bring sensitivity to neutrinos from an even wider range of sources, including galactic supernovae, nuclear reactors, and geological processes. | cygnus: feasibility of a nuclear recoil observatory with directional sensitivity to dark matter and neutrinos |
many cosmological phenomena lead to the production of primordial black holes in the early universe. these phenomena often create a population of black holes with extended mass and spin distributions. as these black holes evaporate via hawking radiation, they can modify various cosmological observables, lead to the production of dark matter, modify the number of effective relativistic degrees of freedom, neff, source a stochastic gravitational wave background and alter the dynamics of baryogenesis. we consider the hawking evaporation of primordial black holes that feature nontrivial mass and spin distributions in the early universe. we demonstrate that the shape of such a distribution can strongly affect most of the aforementioned cosmological observables. we outline the numerical machinery we use to undertake this task. we also release a new version of frisbhee that handles the evaporation of primordial black holes with an arbitrary mass and spin distribution throughout cosmic history. | evaporation of primordial black holes in the early universe: mass and spin distributions |
masses of clusters of galaxies from weak gravitational lensing analyses of ever larger samples are increasingly used as the reference to which baryonic scaling relations are compared. in this paper we revisit the analysis of a sample of 50 clusters studied as part of the canadian cluster comparison project. we examine the key sources of systematic error in cluster masses. we quantify the robustness of our shape measurements and calibrate our algorithm empirically using extensive image simulations. the source redshift distribution is revised using the latest state-of-the-art photometric redshift catalogues that include new deep near-infrared observations. none the less we find that the uncertainty in the determination of photometric redshifts is the largest source of systematic error for our mass estimates. we use our updated masses to determine b, the bias in the hydrostatic mass, for the clusters detected by planck. our results suggest 1 - b = 0.76 ± 0.05 (stat) ± 0.06 (syst), which does not resolve the tension with the measurements from the primary cosmic microwave background. | the canadian cluster comparison project: detailed study of systematics and updated weak lensing masses |
in this paper, we explore the nonsingular cosmology within the framework of the effective field theory (eft) of cosmological perturbations. due to the recently proved no-go theorem, any nonsingular cosmological models based on the cubic galileon suffer from pathologies. we show how the eft could help us clarify the origin of the no-go theorem, and offer us solutions to break the no-go. particularly, we point out that the gradient instability can be removed by using some spatial derivative operators in eft. based on the eft description, we obtain a realistic healthy nonsingular cosmological model, and show the perturbation spectrum can be consistent with the observations. | the effective field theory of nonsingular cosmology |
we propose a framework in which the qcd axion has an exponentially large coupling to photons, relying on the "clockwork" mechanism. we discuss the impact of present and future axion experiments on the parameter space of the model. in addition to the axion, the model predicts a large number of pseudoscalars which can be light and observable at the lhc. in the most favorable scenario, axion dark matter will give a signal in multiple axion detection experiments and the pseudo-scalars will be discovered at the lhc, allowing us to determine most of the parameters of the model. | the photo-philic qcd axion |
we report on the first results from a new microwave cavity search for dark matter axions with masses above 20 μ ev . we exclude axion models with two-photon coupling ga γ γ≳2 ×10-14 gev-1 over the range 23.55 <ma<24.0 μ ev . these results represent two important achievements. first, we have reached cosmologically relevant sensitivity an order of magnitude higher in mass than any existing limits. second, by incorporating a dilution refrigerator and josephson parametric amplifier, we have demonstrated total noise approaching the standard quantum limit for the first time in an axion search. | first results from a microwave cavity axion search at 24 μ ev |
an accurate theoretical template for the galaxy power spectrum is key for the success of ongoing and future spectroscopic surveys. we examine to what extent the effective field theory (eft) of large-scale structure is able to provide such a template and correctly estimate cosmological parameters. to that end, we initiate a blinded challenge to infer cosmological parameters from the redshift-space power spectrum of high-resolution mock catalogs mimicking the boss galaxy sample but covering a 100 times larger cumulative volume. this gigantic simulation volume allows us to separate systematic bias due to theoretical modeling from the statistical error due to sample variance. the challenge is to measure three unknown input parameters used in the simulation: the hubble constant, the matter density fraction, and the clustering amplitude. we present analyses done by two independent teams, who have fitted the mock simulation data generated by yet another independent group. this allows us to avoid any confirmation bias by analyzers and to pin down possible tuning of the specific eft implementations. both independent teams have recovered the true values of the input parameters within subpercent statistical errors corresponding to the total simulation volume. | blinded challenge for precision cosmology with large-scale structure: results from effective field theory for the redshift-space galaxy power spectrum |
in this work, we systematically calculate the mass spectra of the s -wave fully-heavy tetraquark states, b b b ¯b ¯, c c c ¯c ¯, and b b c ¯c ¯, in two nonrelativistic quark models. a tetraquark state may be an admixture of a 6c-6¯ c state and a 3¯ c-3c one, where 6c-6¯ c (3¯ c-3c ) denotes the color configuration with a 6c (3¯c) diquark and a 6¯c (3c) antidiquark. for the tetraquark states b b b ¯b ¯ and c c c ¯c ¯ with jp c=0++ , the 6c-6¯ c state is lower than the 3¯c-3c one in both the two quark models, while the order of the b b c ¯c ¯ states depend on models. the 6c-6¯c and 3¯c-3c mixing effects are induced by the hyperfine interactions between the diquark and antidiquark, while the contributions from the one-gluon-exchange coulomb or the linear confinement potentials vanish for the q q q¯ 'q¯ ' system. with the couple-channel effects, we obtain the similar mass spectra. the numerical results show that the ground q q q¯'q¯' (q =b , c and q'=b , c ) tetraquark states are located above the corresponding scattering states, which indicates that there may not exist a bound state in the scheme of the two quark models. | spectrum of the fully-heavy tetraquark state q q q¯ 'q¯ ' |
after the discovery of the higgs boson, understanding the nature of electroweak symmetry breaking and the associated electroweak phase transition has become the most pressing question in particle physics. answering this question is a priority for experimental studies. data from the lhc and future lepton collider-based higgs factories may uncover new physics coupled to the higgs boson, which can induce the electroweak phase transition to become first order. such a phase transition generates a stochastic background of gravitational waves, which could potentially be detected by a space-based gravitational wave interferometer. in this paper, we survey a few classes of models in which the electroweak phase transition is strongly first order. we identify the observables that would provide evidence of these models at the lhc and next-generation lepton colliders, and we assess whether the corresponding gravitational wave signal could be detected by elisa. we find that most of the models with first-order electroweak phase transition can be covered by the precise measurements of higgs couplings at the proposed higgs factories. we also map out the model space that can be probed with gravitational wave detection by elisa. | probing the electroweak phase transition with higgs factories and gravitational waves |
this report summarizes the present status of neutrino non-standard interactions (nsi). after a brief overview, several aspects of nsis are discussed, including connection to neutrino mass models, model-building and phenomenology of large nsi with both light and heavy mediators, nsi phenomenology in both short- and long-baseline neutrino oscillation experiments, neutrino cross-sections, complementarity of nsi with other low- and high-energy experiments, fits with neutrino oscillation and scattering data, dune sensitivity to nsi, effective field theory of nsi, as well as the relevance of nsi to dark matter and cosmology. we also discuss the open questions and interesting future directions that can be pursued by the community at large. this report is based on talks and discussions during the neutrino theory network nsi workshop held at washington university in st. louis from may 29-31, 2019 (https://indico.cern.ch/event/812851/) | neutrino non-standard interactions: a status report |
this note presents an initial survey design for the nancy grace roman high-latitude time domain survey. this is not meant to be a final or exhaustive list of all the survey strategy choices, but instead presents a viable path towards achieving the desired precision and accuracy of dark energy measurements using type ia supernovae (sne ia). we describe a survey strategy that use six filters (rzyjh and f) and the prism on the roman wide field instrument. this survey has two tiers, one "wide" which targets sne ia at redshifts up to 1 and one "deep" targeting redshifts up to 1.7; for each, four filters are used (with y and j used in both tiers). we propose one field each in the north and south continuous viewing zones, and expect to obtain high-quality distances of $\sim$12,000 sne ia with $\sim$5,000 at z > 1. we propose a wide-tier area of $\sim$19 deg$^2$ and a deep tier of $\sim$5 deg$^2$. exposure times range from 100 s to 900 s for imaging and 900 s to 3600 s for the prism. these exposure times would reach $\sim$25.5 mag and $\sim$26.5 mag for the wide and deep tiers respectively, with deep co-add stacks reaching $\sim$28 mag and $\sim$29 mag. the total survey spans two years, with a total allocation time of six months, and a cadence of $\sim$5 days. | a reference survey for supernova cosmology with the nancy grace roman space telescope |
observations reveal a "bulk flow" in the local universe which is faster and extends to much larger scales than are expected around a typical observer in the standard λcdm cosmology. this is expected to result in a scale-dependent dipolar modulation of the acceleration of the expansion rate inferred from observations of objects within the bulk flow. from a maximum-likelihood analysis of the joint light-curve analysis catalogue of type ia supernovae, we find that the deceleration parameter, in addition to a small monopole, indeed has a much bigger dipole component aligned with the cosmic microwave background dipole, which falls exponentially with redshift z: q0 = qm + qd.n̂ exp(-z/s). the best fit to data yields qd = -8.03 and s = 0.0262 (⇒d ∼ 100 mpc), rejecting isotropy (qd = 0) with 3.9σ statistical significance, while qm = -0.157 and consistent with no acceleration (qm = 0) at 1.4σ. thus the cosmic acceleration deduced from supernovae may be an artefact of our being non-copernican observers, rather than evidence for a dominant component of "dark energy" in the universe. the code used here is available at: https://github.com/rameez3333/dipole_jla | evidence for anisotropy of cosmic acceleration |
modifications of general relativity leave their imprint both on the cosmic expansion history through a non-trivial dark energy equation of state, and on the evolution of cosmological perturbations in the scalar and in the tensor sectors. in particular, the modification in the tensor sector gives rise to a notion of gravitational-wave (gw) luminosity distance, different from the standard electromagnetic luminosity distance, that can be studied with standard sirens at gw detectors such as lisa or third-generation ground based experiments. we discuss the predictions for modified gw propagation from some of the best studied theories of modified gravity, such as horndeski or the more general degenerate higher order scalar-tensor (dhost) theories, non-local infrared modifications of gravity, bigravity theories and the corresponding phenomenon of gw oscillation, as well as theories with extra or varying dimensions. we show that modified gw propagation is a completely generic phenomenon in modified gravity. we then use a simple parametrization of the effect in terms of two parameters (ξ0,n), that is shown to fit well the results from a large class of models, to study the prospects of observing modified gw propagation using supermassive black hole binaries as standard sirens with lisa . we construct mock source catalogs and perform detailed markov chain monte carlo studies of the likelihood obtained from lisa standard sirens alone, as well as by combining them with cmb, bao and sne data to reduce the degeneracies between cosmological parameters. we find that the combination of lisa with the other cosmological datasets allows one to measure the parameter ξ0 that characterizes modified gw propagation to the percent level accuracy, sufficient to test several modified gravity theories. lisa standard sirens can also improve constraints on gw oscillations induced by extra field content by about three orders of magnitude relative to the current capability of ground detectors. we also update the forecasts on the accuracy on h0 and on the dark-energy equation of state using more recent estimates for the lisa sensitivity. | testing modified gravity at cosmological distances with lisa standard sirens |
we use the ages of old astrophysical objects (oao) in the redshift range 0 ≲ z ≲ 8 as stringent tests of the late-time cosmic expansion history. since the age of the universe at any redshift is inversely proportional to h0, requiring that the universe be older than the oldest objects it contains at any redshift, provides an upper limit on h0. using a combination of galaxies imaged from the candels program and various high-z quasars, we construct an age-redshift diagram of ≳100 oao up to z ∼ 8. assuming the λcdm model at late times, we find the 95% confidence level upper limit h0 < 73.2km / s / mpc , in slight disagreement with a host of local h0 measurements. taken at face value, and assuming that the oao ages are reliable, this suggests that ultimately a combination of pre- and post-recombination (z ≲ 10) new physics might be required to reconcile cosmic ages with early-time and local h0 measurements. in the context of the hubble tension, our results motivate the study of either a) combined global pre- and post-recombination modifications to λcdm, or b) local new physics which only affects the local h0 measurements. | implications for the hubble tension from the ages of the oldest astrophysical objects |
based on the assumption that quasars (qsos) and gamma-ray bursts (grbs) represent standardizable candles, we provide evidence that the hubble constant h0 adopts larger values in hemispheres aligned with the cosmic microwave background (cmb) dipole direction. if substantiated, this trend signals a departure from friedmann-lemaître-robertson-walker cosmology. in particular, qsos show a definite trend, whereas our findings in grbs are consistent with an isotropic universe, but we show in a sample of grbs calibrated with type ia supernovae (sne) that this conclusion may change as one focuses on grbs more closely (mis)aligned with the cmb dipole direction. the statistical significance in qsos alone is ≳2 σ , and when combined with similar trends in strong lensing, type ia sne, and calibrated grbs, this increases to ∼3 σ . our findings are consistent with reported discrepancies in the cosmic dipole and anisotropies in galaxy cluster scaling relations. the reported variations in h0 across the sky suggest that hubble tension may be a symptom of a deeper cosmological malaise. | larger h0 values in the cmb dipole direction |
primordial black holes can be produced by density fluctuations generated from delayed vacuum decays of first-order phase transition. the primordial black holes generated at the electroweak phase transition have masses of about 10-5 solar mass. such primordial black holes in the mass range can be tested by current and future microlensing observations, such as subaru hsc, ogle, prime and roman telescope. therefore, we may be able to explore new physics models with strongly first-order electroweak phase transition via primordial black holes. we examine this possibility by using models with first-order electroweak phase transition in the standard model effective field theory with dimension 6 and 8 operators. we find that depending on parameters of the phase transition a sufficient number of primordial black holes can be produced to be observed by above mentioned experiments. our results would suggest that primordial black holes can be used as a new probe of models with strongly first-order electroweak phase transition, which has complementarity with measurements of the triple higgs boson coupling at future collider experiments and observations of gravitational waves at future space-based interferometers. | primordial black holes as a probe of strongly first-order electroweak phase transition |
this study presents a catalog of 8107 molecular clouds that covers the entire galactic plane and includes 98% of the 12co emission observed within b+/- 5^\circ . the catalog was produced using a hierarchical cluster identification method applied to the result of a gaussian decomposition of the dame et al. data. the total h2 mass in the catalog is 1.2× {10}9 {m}⊙ , in agreement with previous estimates. we find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. the most probable cloud size is r∼ 30 pc. we find that m\propto {r}2.2+/- 0.2, with no correlation between the cloud surface density, σ, and r. in contrast with the general idea, we find a rather large range of values of σ, from 2 to 300 m⊙ pc-2, and a systematic decrease with increasing galactic radius, {r}{gal}. the cloud velocity dispersion and the normalization {σ }0={σ }v/{r}1/2 both decrease systematically with {r}{gal}. when studied over the whole galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between {σ }v and {{σ }} r. the normalization of this correlation is constant to better than a factor of two for {r}{gal}< 20 {kpc}. this relation is used to disentangle the ambiguity between near and far kinematic distances. we report a strong variation of the turbulent energy injection rate. in the outer galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner galaxy. | physical properties of molecular clouds for the entire milky way disk |
we introduce new modules in the open-source pycbc gravitational-wave astronomy toolkit that implement bayesian inference for compact-object binary mergers. we review the bayesian inference methods implemented and describe the structure of the modules. we demonstrate that the pycbc inference modules produce unbiased estimates of the parameters of a simulated population of binary black hole mergers. we show that the parameters’ posterior distributions obtained using our new code agree well with the published estimates for binary black holes in the first advanced ligo-virgo observing run. | pycbc inference: a python-based parameter estimation toolkit for compact binary coalescence signal |
we have performed the first three-dimensional simulations of strong first-order thermal phase transitions in the early universe. for deflagrations, we find that the rotational component of the fluid velocity increases as the transition strength is increased. for detonations, however, the rotational velocity component remains constant and small. we also find that the efficiency with which kinetic energy is transferred to the fluid falls below theoretical expectations as we increase the transition strength. the probable origin of the kinetic energy deficit is the formation of reheated droplets of the metastable phase during the collision, slowing the bubble walls. the rate of increase in the gravitational wave energy density for deflagrations in strong transitions is suppressed compared to that predicted in earlier work. this is largely accounted for by the reduction in kinetic energy. current modeling therefore substantially overestimates the gravitational wave signal for strong transitions with deflagrations, in the most extreme case by a factor of 103. detonations are less affected. | vorticity, kinetic energy, and suppressed gravitational-wave production in strong first-order phase transitions |
the nature of dark matter, the invisible substance making up over $80\%$ of the matter in the universe, is one of the most fundamental mysteries of modern physics. ultralight bosons such as axions, axion-like particles or dark photons could make up most of the dark matter. couplings between such bosons and nuclear spins may enable their direct detection via nuclear magnetic resonance (nmr) spectroscopy: as nuclear spins move through the galactic dark-matter halo, they couple to dark-matter and behave as if they were in an oscillating magnetic field, generating a dark-matter-driven nmr signal. as part of the cosmic axion spin precession experiment (casper), an nmr-based dark-matter search, we use ultralow-field nmr to probe the axion-fermion "wind" coupling and dark-photon couplings to nuclear spins. no dark matter signal was detected above background, establishing new experimental bounds for dark-matter bosons with masses ranging from $1.8\times 10^{-16}$ to $7.8\times 10^{-14}$ ev. | constraints on bosonic dark matter from ultralow-field nuclear magnetic resonance |
we examine in depth a recent proposal to utilize superfluid helium for direct detection of sub-mev mass dark matter. for sub-kev recoil energies, nuclear scattering events in liquid helium primarily deposit energy into long-lived phonon and roton quasiparticle excitations. if the energy thresholds of the detector can be reduced to the mev scale, then dark matter as light as ∼mev can be reached with ordinary nuclear recoils. if, on the other hand, two or more quasiparticle excitations are directly produced in the dark matter interaction, the kinematics of the scattering allows sensitivity to dark matter as light as ∼kev at the same energy resolution. we present in detail the theoretical framework for describing excitations in superfluid helium, using it to calculate the rate for the leading dark matter scattering interaction, where an off-shell phonon splits into two or more higher-momentum excitations. we validate our analytic results against the measured and simulated dynamic response of superfluid helium. finally, we apply this formalism to the case of a kinetically mixed hidden photon in the superfluid, both with and without an external electric field to catalyze the processes. | light dark matter in superfluid helium: detection with multi-excitation production |
we consider the effects of nonminimal couplings to curvature of the form ξss2r for three types of scalars: the higgs boson, the inflaton, and a scalar dark matter candidate. we compute the abundance of dark matter produced by these nonminimal couplings to gravity and compare to similar results with minimal couplings. we also compute the contribution to the radiation bath during reheating. the main effect is a potential augmentation of the maximum temperature during reheating. a model independent limit of o (1012) gev is obtained. for couplings ξs≳o (1 ), these dominate over minimal gravitational interactions. | gravitational portals with nonminimal couplings |
a variety of observations impose upper limits at the nano gauss level on magnetic fields that are coherent on inter-galactic scales while blazar observations indicate a lower bound ∼10‑16 g. such magnetic fields can play an important astrophysical role, for example at cosmic recombination and during structure formation, and also provide crucial information for particle physics in the early universe. magnetic fields with significant energy density could have been produced at the electroweak phase transition. the evolution and survival of magnetic fields produced on sub-horizon scales in the early universe, however, depends on the magnetic helicity which is related to violation of symmetries in fundamental particle interactions. the generation of magnetic helicity requires new cp violating interactions that can be tested by accelerator experiments via decay channels of the higgs particle. | progress on cosmological magnetic fields |
the nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the standard model that are still elusive to experiments. among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the γ-ray sky have come to prominence over the last few years, because of the excellent sensitivity of the large area telescope (lat) on the fermi gamma-ray space telescope mission. the lat energy range from 20 mev to above 300 gev is particularly well suited for searching for products of the interactions of dark matter particles. in this report we describe methods used to search for evidence of dark matter with the lat, and review the status of searches performed with up to six years of lat data. we also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, considering both statistical and systematic uncertainties. we project the expected sensitivities of each search method for 10 and 15 years of lat data taking. in particular, we find that the sensitivity of searches targeting dwarf galaxies, which provide the best limits currently, will improve faster than the square root of observing time. current lat limits for dwarf galaxies using six years of data reach the thermal relic level for masses up to 120 gev for the b b ¯ annihilation channel for reasonable dark matter density profiles. with projected discoveries of additional dwarfs, these limits could extend to about 250 gev. with as much as 15 years of lat data these searches would be sensitive to dark matter annihilations at the thermal relic cross section for masses to greater than 400 gev (200 gev) in the b b ¯ (τ+τ-) annihilation channels. | sensitivity projections for dark matter searches with the fermi large area telescope |
we use the largest sample of z∼ 6 galaxies to date from the first four hubble frontier fields clusters to set constraints on the shape of the z∼ 6 luminosity functions (lfs) to fainter than {m}{uv,{ab}}=-14 mag. we quantify, for the first time, the impact of magnification uncertainties on lf results and thus provide more realistic constraints than other recent work. our simulations reveal that, for the highly magnified sources, the systematic uncertainties can become extremely large fainter than -14 mag, reaching several orders of magnitude at 95% confidence at approximately -12 mag. our new forward-modeling formalism incorporates the impact of magnification uncertainties into the lf results by exploiting the availability of many independent magnification models for the same cluster. one public magnification model is used to construct a mock high-redshift galaxy sample that is then analyzed using the other magnification models to construct an lf. large systematic errors occur at high magnifications (μ ≳ 30) because of differences between the models. the volume densities we derive for faint (≳-17 mag) sources are ∼3-4× lower than one recent report and give a faint-end slope α =-1.92+/- 0.04, which is 3.0-3.5σ shallower (including or not including the size uncertainties, respectively). we introduce a new curvature parameter δ to model the faint end of the lf and demonstrate that the observations permit (at 68% confidence) a turn-over at z∼ 6 in the range of -15.3 to -14.2 mag, depending on the assumed lensing model. the present consideration of magnification errors and new size determinations raise doubts about previous reports regarding the form of the lf at > -14 {mag}. we discuss the implications of our turn-over constraints in the context of recent theoretical predictions. | the z ∼ 6 luminosity function fainter than -15 mag from the hubble frontier fields: the impact of magnification uncertainties |
sdss j015957.64+003310.5 is an x-ray selected, z = 0.31 active galactic nucleus (agn) from the stripe 82x survey that transitioned from a type 1 quasar to a type 1.9 agn between 2000 and 2010. this is the most distant agn, and first quasar, yet observed to have undergone such a dramatic change. we re-observed the source with the double spectrograph on the palomar 5 m telescope in 2014 july and found that the spectrum is unchanged since 2010. from fitting the optical spectra, we find that the agn flux dropped by a factor of 6 between 2000 and 2010 while the broad hα emission faded and broadened. serendipitous x-ray observations caught the source in both the bright and dim state, showing a similar 2-10 kev flux diminution as the optical while lacking signatures of obscuration. the optical and x-ray changes coincide with g-band magnitude variations over multiple epochs of stripe 82 observations. we demonstrate that variable absorption, as might be expected from the simplest agn unification paradigm, does not explain the observed photometric or spectral properties. we interpret the changing state of j0159+0033 to be caused by dimming of the agn continuum, reducing the supply of ionizing photons available to excite gas in the immediate vicinity around the black hole. j0159+0033 provides insight into the intermittency of black hole growth in quasars, as well as an unprecedented opportunity to study quasar physics (in the bright state) and the host galaxy (in the dim state), which has been impossible to do in a single sources until now. | the discovery of the first “changing look” quasar: new insights into the physics and phenomenology of active galactic nucleus |
radio synchrotron emission, its polarization and faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30 \upmu g) and in central starburst regions (50-100 \upmu g). such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. the strongest ordered fields (10-15 \upmu g) are generally found in interarm regions. in galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies and in central regions. ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the intergalactic medium.—faraday rotation measures of the diffuse polarized radio emission from galaxy disks reveal large-scale spiral patterns that can be described by the superposition of azimuthal modes; these are signatures of regular fields generated by mean-field dynamos. "magnetic arms" between gaseous spiral arms may also be products of dynamo action, but need a stable spiral pattern to develop. helically twisted field loops winding around spiral arms were found in two galaxies so far. large-scale field reversals, like the one found in the milky way, could not yet be detected in external galaxies. in radio halos around edge-on galaxies, ordered magnetic fields with x-shaped patterns are observed. the origin and evolution of cosmic magnetic fields, in particular their first occurrence in young galaxies and their dynamical importance during galaxy evolution, will be studied with forthcoming radio telescopes like the square kilometre array. | magnetic fields in spiral galaxies |
the wide field infrared survey telescope (wfirst) is the next nasa astrophysics flagship mission, to follow the james webb space telescope. the wfirst mission was chosen as the top-priority large space mission of the 2010 astronomy and astrophysics decadal survey in order to achieve three primary goals: to study dark energy via a wide-field imaging survey, to study exoplanets via a microlensing survey, and to enable a guest observer program. here we assess the ability of the several wfirst designs to achieve the goal of the microlensing survey to discover a large sample of cold, low-mass exoplanets with semimajor axes beyond roughly one astronomical unit, which are largely impossible to detect with any other technique. we present the results of a suite of simulations that span the full range of the proposed wfirst architectures, from the original design envisioned by the decadal survey, to the current design, which utilizes a 2.4 m telescope donated to nasa. by studying such a broad range of architectures, we are able to determine the impact of design trades on the expected yields of detected exoplanets. in estimating the yields we take particular care to ensure that our assumed galactic model predicts microlensing event rates that match observations, consider the impact that inaccuracies in the galactic model might have on the yields, and ensure that numerical errors in light-curve computations do not bias the yields for the smallest-mass exoplanets. for the nominal baseline wfirst design and a fiducial planet mass function, we predict that a total of ∼1400 bound exoplanets with mass greater than ∼0.1 m ⊕ should be detected, including ∼200 with mass ≲3 m ⊕. wfirst should have sensitivity to planets with mass down to ∼0.02 m ⊕, or roughly the mass of ganymede. | predictions of the wfirst microlensing survey. i. bound planet detection rates |
preface to the first edition; preface to the second edition; 1. cosmic rays; 2. cosmic ray data; 3. particle physics; 4. hadronic interactions and accelerator data; 5. cascade equations; 6. atmospheric muons and neutrinos; 7. neutrino masses and oscillations; 8. muons and neutrinos underground; 9. cosmic rays in the galaxy; 10. extragalactic propagation of cosmic rays; 11. astrophysical - rays and neutrinos; 12. acceleration; 13. supernovae in the milky way; 14. astrophysical accelerators and beam dumps; 15. electromagnetic cascades; 16. extensive air showers; 17. very high energy cosmic rays; 18. neutrino astronomy; a.1. units, constants and definitions; a.2. references to flux measurements; a.3. particle flux, density, and interaction cross section; a.4. fundamentals of scattering theory; a.5. regge amplitude; a.6. glauber model of nuclear cross sections; a.7. earth's atmosphere; a.8. longitudinal development of air showers; a.9. secondary positrons and electrons; a.10. liouville's theorem and cosmic ray propagation; a.11. cosmology and distances measures; a.12. the hillas splitting algorithm; references; index. | cosmic rays and particle physics |
the curvature perturbations produced during an early era of inflation are known to have quasi-gaussian distribution functions close to their maximum, where they are well constrained by measurements of the cosmic microwave background anisotropies and of the large-scale structures. in contrast, the tails of these distributions are poorly known, although this part is the relevant one for rare, extreme objects such as primordial black holes. we show that these tails are highly non-gaussian, and cannot be described with standard non-gaussian expansions, that are designed to approximate the distributions close to their maximum only. using the stochastic-δ n formalism, we develop a generic framework to compute the tails, which are found to have an exponential, rather than gaussian, decay. these exponential tails are inevitable, and do not require any non-minimal feature as they simply result from the quantum diffusion of the inflaton field along its potential. we apply our formalism to a few relevant single-field, slow-roll inflationary potentials, where our analytical treatment is confirmed by comparison with numerical results. we discuss the implications for the expected abundance of primordial black holes in these models, and highlight that it can differ from standard results by several orders of magnitude. in particular, we find that potentials with an inflection point overproduce primordial black holes, unless slow roll is violated. | the exponential tail of inflationary fluctuations: consequences for primordial black holes |
the distribution of the non-luminous matter in galaxies of different luminosity and hubble type is much more than a proof of the existence of dark particles governing the structures of the universe. here, we will review the complex but well-ordered scenario of the properties of the dark halos also in relation with those of the baryonic components they host. moreover, we will present a number of tight and unexpected correlations between selected properties of the dark and the luminous matter. such entanglement evolves across the varying properties of the luminous component and it seems to unequivocally lead to a dark particle able to interact with the standard model particles over cosmological times. this review will also focus on whether we need a paradigm shift, from pure collisionless dark particles emerging from "first principles", to particles that we can discover only by looking to how they have designed the structure of the galaxies. | the distribution of dark matter in galaxies |
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