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we present reduced data and data products from the 3d-hst survey, a 248-orbit hst treasury program. the survey obtained wfc3 g141 grism spectroscopy in four of the five candels fields: aegis, cosmos, goods-s, and uds, along with wfc3 h 140 imaging, parallel acs g800l spectroscopy, and parallel i 814 imaging. in a previous paper, we presented photometric catalogs in these four fields and in goods-n, the fifth candels field. here we describe and present the wfc3 g141 spectroscopic data, again augmented with data from go-1600 in goods-n (pi: b. weiner). we developed software to automatically and optimally extract interlaced two-dimensional (2d) and one-dimensional (1d) spectra for all objects in the skelton et al. (2014) photometric catalogs. the 2d spectra and the multi-band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxies explicitly into account. the resulting catalog has redshifts and line strengths (where available) for 22,548 unique objects down to {{jh}}{ir}≤slant 24 (79,609 unique objects down to {{jh}}{ir}≤slant 26). of these, 5459 galaxies are at z\gt 1.5 and 9621 are at 0.7\lt z\lt 1.5, where hα falls in the g141 wavelength coverage. the typical redshift error for {{jh}}{ir}≤slant 24 galaxies is {σ }z≈ 0.003× (1+z), i.e., one native wfc3 pixel. the 3σ limit for emission line fluxes of point sources is 2.1× {10}-17 erg s-1 cm-2. all 2d and 1d spectra, as well as redshifts, line fluxes, and other derived parameters, are publicly available.18 | the 3d-hst survey: hubble space telescope wfc3/g141 grism spectra, redshifts, and emission line measurements for ~ 100,000 galaxies |
the proposed ldmx experiment would provide roughly a meter-long region of instrumented tracking and calorimetry that acts as a beam stop for multi-gev electrons in which each electron is tagged and its evolution measured. this would offer an unprecedented opportunity to access both collider-invisible and ultrashort-lifetime decays of new particles produced in electron (or muon) nuclear fixed-target collisions. in this paper, we show that the missing momentum channel and displaced decay signals in such an experiment could provide world-leading sensitivity to sub-gev dark matter, millicharged particles, and visibly or invisibly decaying axions, scalars, dark photons, and a range of other new physics scenarios. | dark matter, millicharges, axion and scalar particles, gauge bosons, and other new physics with ldmx |
this white paper summarizes recent progress in the cosmological bootstrap, an approach to the study of the statistics of primordial fluctuations from consistency with unitarity, locality and symmetry assumptions. we review the key ideas of the bootstrap method, with an eye towards future directions and ambitions of the program. focusing on recent progress involving de sitter and quasi-de sitter backgrounds, we highlight the role of singularities and unitarity in constraining the form of the correlators. we also discuss nonperturbative formulations of the bootstrap, connections to anti-de sitter space, and potential implications for holography. | snowmass white paper: the cosmological bootstrap |
this paper presents the third data release of the hyper suprime-cam subaru strategic program (hsc-ssp), a wide-field multi-band imaging survey with the subaru 8.2 m telescope. hsc-ssp has three survey layers (wide, deep, and ultradeep) with different area coverages and depths, designed to address a wide array of astrophysical questions. this third release from hsc-ssp includes data from 278 nights of observing time and covers about 670 deg2 in all five broad-band filters (grizy) at the full depth (~26 mag at 5σ depending on filter) in the wide layer. if we include partially observed areas, the release covers 1470 deg2. the deep and ultradeep layers have $\sim\! 80\%$ of the originally planned integration times, and are considered done, as we have slightly changed the observing strategy in order to compensate for various time losses. there are a number of updates in the image processing pipeline. of particular importance is the change in the sky subtraction algorithm; we subtract the sky on small scales before the detection and measurement stages, which has significantly reduced the number of false detections. thanks to this and other updates, the overall quality of the processed data has improved since the previous release. however, there are limitations in the data (for example, the pipeline is not optimized for crowded fields), and we encourage the user to check the quality assurance plots as well as a list of known issues before exploiting the data. the data release website is <https://hsc-release.mtk.nao.ac.jp>. | third data release of the hyper suprime-cam subaru strategic program |
dark matter wimp search with liquid xenon (darwin) will be an experiment for the direct detection of dark matter using a multi-ton liquid xenon time projection chamber at its core. its primary goal will be to explore the experimentally accessible parameter space for weakly interacting massive particles (wimps) in a wide mass-range, until neutrino interactions with the target become an irreducible background. the prompt scintillation light and the charge signals induced by particle interactions in the xenon will be observed by vuv sensitive, ultra-low background photosensors. besides its excellent sensitivity to wimps above a mass of 5 gev/c2, such a detector with its large mass, low-energy threshold and ultra-low background level will also be sensitive to other rare interactions. it will search for solar axions, galactic axion-like particles and the neutrinoless double-beta decay of 136xe, as well as measure the low-energy solar neutrino flux with < 1% precision, observe coherent neutrino-nucleus interactions, and detect galactic supernovae. we present the concept of the darwin detector and discuss its physics reach, the main sources of backgrounds and the ongoing detector design and r&d efforts. | darwin: towards the ultimate dark matter detector |
primordial black holes (pbh) arise naturally from high peaks in the curvature power spectrum of near-inflection-point single-field inflation, and could constitute today the dominant component of the dark matter in the universe. in this letter we explore the possibility that a broad spectrum of pbh is formed in models of critical higgs inflation (chi), where the near-inflection point is related to the critical value of the rge running of both the higgs self-coupling λ (μ) and its non-minimal coupling to gravity ξ (μ). we show that, for a wide range of model parameters, a half-domed-shaped peak in the matter spectrum arises at sufficiently small scales that it passes all the constraints from large scale structure observations. the predicted cosmic microwave background spectrum at large scales is in agreement with planck 2015 data, and has a relatively large tensor-to-scalar ratio that may soon be detected by b-mode polarization experiments. moreover, the wide peak in the power spectrum gives an approximately lognormal pbh distribution in the range of masses 0.01- 100m⊙, which could explain the ligo merger events, while passing all present pbh observational constraints. the stochastic background of gravitational waves coming from the unresolved black-hole-binary mergers could also be detected by lisa or pta. furthermore, the parameters of the chi model are consistent, within 2σ, with the measured higgs parameters at the lhc and their running. future measurements of the pbh mass spectrum could allow us to obtain complementary information about the higgs couplings at energies well above the ew scale, and thus constrain new physics beyond the standard model. | primordial black hole production in critical higgs inflation |
advanced actpol is a polarization-sensitive upgrade for the 6 m aperture atacama cosmology telescope, adding new frequencies and increasing sensitivity over the previous actpol receiver. in 2016, advanced actpol will begin to map approximately half the sky in five frequency bands (28-230 ghz). its maps of primary and secondary cosmic microwave background anisotropies—imaged in intensity and polarization at few arcminute-scale resolution—will enable precision cosmological constraints and also a wide array of cross-correlation science that probes the expansion history of the universe and the growth of structure via gravitational collapse. to accomplish these scientific goals, the advanced actpol receiver will be a significant upgrade to the actpol receiver, including four new multichroic arrays of cryogenic, feedhorn-coupled almn transition edge sensor polarimeters (fabricated on 150 mm diameter wafers); a system of continuously rotating meta-material silicon half-wave plates; and a new multiplexing readout architecture which uses superconducting quantum interference devices and time division to achieve a 64-row multiplexing factor. here we present the status and scientific goals of the advanced actpol instrument, emphasizing the design and implementation of the advanced actpol cryogenic detector arrays. | advanced actpol cryogenic detector arrays and readout |
we present jwst nirspec prism spectroscopy of gravitationally lensed galaxies at $z\gtrsim9$ found behind the massive galaxy cluster abell 2744 in the uncover cycle 1 treasury program. we confirm the source redshift via emission lines and/or the ly$\alpha$ break feature for ten galaxies at z=8.50-13.08 down to $m_{\rm uv}=-17.3$. we achieve a high confirmation rate of 100\% for $z>9$ candidates reported in atek et al. (2023). using six sources with multiple emission line detections, we find that the offset of the redshift estimates between the lines and the ly$\alpha$ break alone with prism can be as large as $\pm0.2$, raising caution in designing future follow-up spectroscopy for the break-only sources. with spec-$z$ confirmed sources in uncover and the literature, we derive lower limits on the rest-frame ultraviolet (uv) luminosity function (lf) at $z\simeq9$-12 and find these lower limits to be consistent with recent photometric measurements. we identify at least two unambiguous and several possible active galactic nucleus (agn) systems based on x-ray emission, broad line (bl) h$\beta$, high ionization line (e.g., niv]1487, civ1549) detections, and excess in uvlf. this requires the agn lfs at $z\simeq$ 9-10 to be comparable or even higher than the x-ray agn lf estimated at $z\sim6$ and indicates a plausible cause of the high abundance of $z>9$ galaxies claimed in recent photometric studies may be agns. one uv-luminous source is confirmed at the same redshift as a dusty bl agn at $z=8.50$ with a physical separation of 380 kpc in the source plane. these two sources show blueward ly$\alpha$ line or continuum emission, suggesting that they reside in the same ionized bubble with a radius of $7.69\pm0.18$ pmpc. our results imply that agns have a non-negligible contribution to cosmic reionization. | uncover: a nirspec census of lensed galaxies at z=8.50-13.08 probing a high agn fraction and ionized bubbles in the shadow |
the hubble tension has now grown to a level of significance which can no longer be ignored and calls for a solution which, despite a huge number of attempts, has so far eluded us. significant efforts in the literature have focused on early-time modifications of λcdm, introducing new physics operating prior to recombination and reducing the sound horizon. in this opinion paper i argue that early-time new physics alone will always fall short of fully solving the hubble tension. i base my arguments on seven independent hints, related to (1) the ages of the oldest astrophysical objects, (2) considerations on the sound horizon-hubble constant degeneracy directions in cosmological data, (3) the important role of cosmic chronometers, (4) a number of "descending trends" observed in a wide variety of low-redshift datasets, (5) the early integrated sachs-wolfe effect as an early-time consistency test of λcdm, (6) early-universe physics insensitive and uncalibrated cosmic standard constraints on the matter density, and finally (7) equality wavenumber-based constraints on the hubble constant from galaxy power spectrum measurements. i argue that a promising way forward should ultimately involve a combination of early- and late-time (but non-local—in a cosmological sense, i.e., at high redshift) new physics, as well as local (i.e., at z∼0) new physics, and i conclude by providing reflections with regards to potentially interesting models which may also help with the s8 tension. | seven hints that early-time new physics alone is not sufficient to solve the hubble tension |
the underlying physics of qcd phase transition in the early universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice qcd data while with its duration of the first-order phase transition (fopt) left undetermined. at specific baryon chemical potential, the first-order qcd phase transition agrees with the observational constraint of baryon asymmetry. it therefore provides a scenario for phase transition gravitational waves (gws) within the standard model of particle physics. if these background gws could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array (pta) observations, the duration of this fopt can be well constrained but disfavored by the constraints from curvature perturbations. however, the associated primordial black holes are still allowed by current observations. therefore, either the qcd phase transition is not described by our holographic model or the other gw sources must be presented to dominate over the gws from this fopt. | constraints on holographic qcd phase transitions from pta observations |
the symmetry can be broken at high temperature and then restored at low temperature, which is the so-called \emph{high temperature symmetry breaking}. it often appears in some theories such as the high scale electroweak baryogenesis mechanism. in this paper, we probe the high temperature $\mathbb{z}_2$ symmetry breaking with gravitational waves (gws) from domain wall annihilation. we first introduce a scalar with $\mathbb{z}_2$ symmetry and few of singlet fermions that interact with scalar through a five-dimension operator. this can lead to the scalar potential has a non-zero minimum at high temperature. at the early stage, the scalar is pinned at symmetric phase due to the large hubble fraction. when the scalar thermal mass becomes comparable to the hubble parameter, it can quickly roll down to the minimum of potential. then the $\mathbb{z}_2$ symmetry is spontaneously broken and the domain walls will form. with the decrease of temperature, $\mathbb{z}_2$ symmetry will be restored. we find that if domain walls are formed at $\mathcal{o}(10^{9})~ \rm gev$, the gw produced by domain wall annihilation is expected to be observed by bbo, ce and et. in addition, we also discuss the relationships between this scenario and nanograv signal. | probing the high temperature symmetry breaking with gravitational waves from domain walls |
we examine interactions between dark matter and dark energy in light of the latest cosmological observations, focusing on a specific model with coupling proportional to the dark energy density. our data includes cosmic microwave background (cmb) measurements from the planck 2018 legacy data release, late-time measurements of the expansion history from baryon acoustic oscillations (bao) and supernovae type ia (sneia), galaxy clustering and cosmic shear measurements from the dark energy survey year 1 results, and the 2019 local distance ladder measurement of the hubble constant h0 from the hubble space telescope. considering planck data both in combination with bao or sneia data reduces the h0 tension to a level which could possibly be compatible with a statistical fluctuation. the very same model also significantly reduces the ωm -σ8 tension between cmb and cosmic shear measurements. interactions between the dark sectors of our universe remain therefore a promising joint solution to these persisting cosmological tensions. | interacting dark energy in the early 2020s: a promising solution to the h0 and cosmic shear tensions |
we review the effective field theory (eft) approach to gravitational dynamics. we focus on extended objects in long-wavelength backgrounds and gravitational wave emission from spinning binary systems. we conclude with an introduction to eft methods for the study of cosmological large scale structures. | the effective field theorist's approach to gravitational dynamics |
the effective number of relativistic neutrino species is a fundamental probe of the early universe, and its measurement represents a key constraint on many scenarios beyond the standard model of particle physics. in light of this, an accurate prediction of neff in the standard model is of pivotal importance. in this work, we consider the last ingredient needed to accurately calculate neffsm: standard zero and finite-temperature qed corrections to e+e-↔ν ν ¯ interaction rates during neutrino decoupling at temperatures around t ∼mev . we find that this effect leads to a reduction of -0.0007 in neffsm. this next-to-leading-order qed correction to the interaction rates, together with finite-temperature qed corrections to the electromagnetic density of the plasma, and the effect of neutrino oscillations, implies that neffsm=3.043 with a theoretical uncertainty that is much smaller than any projected observational sensitivity. | neff in the standard model at nlo is 3.043 |
aims: the euclid space telescope will measure the shapes and redshifts of galaxies to reconstruct the expansion history of the universe and the growth of cosmic structures. the estimation of the expected performance of the experiment, in terms of predicted constraints on cosmological parameters, has so far relied on various individual methodologies and numerical implementations, which were developed for different observational probes and for the combination thereof. in this paper we present validated forecasts, which combine both theoretical and observational ingredients for different cosmological probes. this work is presented to provide the community with reliable numerical codes and methods for euclid cosmological forecasts.methods: we describe in detail the methods adopted for fisher matrix forecasts, which were applied to galaxy clustering, weak lensing, and the combination thereof. we estimated the required accuracy for euclid forecasts and outline a methodology for their development. we then compare and improve different numerical implementations, reaching uncertainties on the errors of cosmological parameters that are less than the required precision in all cases. furthermore, we provide details on the validated implementations, some of which are made publicly available, in different programming languages, together with a reference training-set of input and output matrices for a set of specific models. these can be used by the reader to validate their own implementations if required.results: we present new cosmological forecasts for euclid. we find that results depend on the specific cosmological model and remaining freedom in each setting, for example flat or non-flat spatial cosmologies, or different cuts at non-linear scales. the numerical implementations are now reliable for these settings. we present the results for an optimistic and a pessimistic choice for these types of settings. we demonstrate that the impact of cross-correlations is particularly relevant for models beyond a cosmological constant and may allow us to increase the dark energy figure of merit by at least a factor of three. | euclid preparation. vii. forecast validation for euclid cosmological probes |
the current status of baryogenesis is reviewed, with an emphasis on electroweak baryogenesis and leptogenesis. the first detailed studies were carried out for su (5 ) grand unified theory (gut) models where c p -violating decays of leptoquarks generate a baryon asymmetry. these gut models were excluded by the discovery of unsuppressed, (b +l )-violating sphaleron processes at high temperatures. yet a new possibility emerged: electroweak baryogenesis. here sphaleron processes generate a baryon asymmetry during a strongly first-order phase transition. this mechanism has been studied in detail in many extensions of the standard model. however, constraints from the lhc and from low-energy precision experiments exclude most of the known models, leaving composite higgs models of electroweak symmetry breaking as an interesting possibility. sphaleron processes are also the basis of leptogenesis, where c p -violating decays of heavy right-handed neutrinos generate a lepton asymmetry that is partially converted to a baryon asymmetry. this mechanism is closely related to that of gut baryogenesis, and simple estimates based on gut models can explain the order of magnitude of the observed baryon-to-photon ratio. in the one-flavor approximation an upper bound on the light-neutrino masses has been derived that is consistent with the cosmological upper bound on the sum of neutrino masses. for quasidegenerate right-handed neutrinos the leptogenesis temperature can be lowered from the gut scale down to the weak scale, and c p -violating oscillations of gev sterile neutinos can also lead to successful leptogenesis. significant progress has been made in developing a full field-theoretical description of thermal leptogenesis, which demonstrated that interactions with gauge bosons of the thermal plasma play a crucial role. finally, recent ideas on how the seesaw mechanism and b -l breaking at the gut scale can be probed by gravitational waves are discussed. | baryogenesis from the weak scale to the grand unification scale |
we present results from an analysis of all data taken by the bicep2 and keck array cosmic microwave background (cmb) polarization experiments up to and including the 2014 observing season. this includes the first keck array observations at 95 ghz. the maps reach a depth of 50 nk deg in stokes q and u in the 150 ghz band and 127 nk deg in the 95 ghz band. we take auto- and cross-spectra between these maps and publicly available maps from wmap and planck at frequencies from 23 to 353 ghz. an excess over lensed λ cdm is detected at modest significance in the 95 ×150 b b spectrum, and is consistent with the dust contribution expected from our previous work. no significant evidence for synchrotron emission is found in spectra such as 23 ×95 , or for correlation between the dust and synchrotron sky patterns in spectra such as 23 ×353 . we take the likelihood of all the spectra for a multicomponent model including lensed λ cdm , dust, synchrotron, and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r ) using priors on the frequency spectral behaviors of dust and synchrotron emission from previous analyses of wmap and planck data in other regions of the sky. this analysis yields an upper limit r0.05<0.09 at 95% confidence, which is robust to variations explored in analysis and priors. combining these b -mode results with the (more model-dependent) constraints from planck analysis of cmb temperature plus baryon acoustic oscillations and other data yields a combined limit r0.05<0.07 at 95% confidence. these are the strongest constraints to date on inflationary gravitational waves. | improved constraints on cosmology and foregrounds from bicep2 and keck array cosmic microwave background data with inclusion of 95 ghz band |
we study the system of axion strings that forms in the early universe if the peccei-quinn symmetry is restored after inflation. using numerical simulations, we establish the existence of an asymptotic solution to which the system is attracted independently of the initial conditions. we study in detail the properties of this solution, including the average number of strings per hubble patch, the distribution of loops and long strings, the way that different types of radiation are emitted, and the shape of the spectrum of axions produced. we find clear evidence of logarithmic violations of the scaling properties of the attractor solution. we also find that, while most of the axions are emitted with momenta of order hubble, most of the axion energy density is contained in axions with energy of order the string core scale, at least in the parameter range available in the simulation. while such a spectrum would lead to a negligible number density of relic axions from strings when extrapolated to the physical parameter region, we show that the presence of small logarithmic corrections to the spectrum shape could completely alter such a conclusion. a detailed understanding of the evolution of the axion spectrum is therefore crucial for a reliable estimate of the relic axion abundance from strings. | axions from strings: the attractive solution |
desi (dark energy spectropic instrument) is a stage iv ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. the desi instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. the fibers feed ten three-arm spectrographs with resolution $r= \lambda/\delta\lambda$ between 2000 and 5500, depending on wavelength. the desi instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. this powerful instrument will be installed at prime focus on the 4-m mayall telescope in kitt peak, arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. the desi collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use. | the desi experiment part ii: instrument design |
in this paper, we propose a novel mechanism in 𝕋2-inflation to enhance the power spectrum large enough to seed primordial black holes (pbhs) formation. to accomplish this, we consider the coupling function between the inflaton field and 𝕋2 = tμνtμν term. pbhs formed within this scenario can contribute partially or entirely to dark matter (dm) abundance. furthermore, the amplification in the scalar power spectrum will concurrently produce significant scalar-induced gravitational waves (sigws) as a second-order effect. in addition, the energy spectrum associated with sigws can be compatible with the recent nanograv 15-year stochastic gravitational wave detection and fall into the sensitivity range of other forthcoming gw observatories. | pbhs and gws from 𝕋2-inflation and nanograv 15-year data |
we present new direct-detection constraints on ev-to-gev dark matter interacting with electrons using a prototype detector of the sub-electron-noise skipper-ccd experimental instrument. the results are based on data taken in the minos cavern at the fermi national accelerator laboratory. we focus on data obtained with two distinct readout strategies. for the first strategy, we read out the skipper ccd continuously, accumulating an exposure of 0.177 g day. while we observe no events containing three or more electrons, we find a large one- and two-electron background event rate, which we attribute to spurious events induced by the amplifier in the skipper-ccd readout stage. for the second strategy, we take five sets of data in which we switch off all amplifiers while exposing the skipper ccd for 120 ks, and then read out the data through the best prototype amplifier. we find a one-electron event rate of (3.51 ±0.10 )×10-3 events /pixel /day , which is almost 2 orders of magnitude lower than the one-electron event rate observed in the continuous-readout data, and a two-electron event rate of (3.18-0.55+0.86)×10-5 events /pixel /day . we again observe no events containing three or more electrons, for an exposure of 0.069 g day. we use these data to derive world-leading constraints on dark matter-electron scattering for masses between 500 kev and 5 mev, and on dark-photon dark matter being absorbed by electrons for a range of masses below 12.4 ev. | sensei: direct-detection constraints on sub-gev dark matter from a shallow underground run using a prototype skipper ccd |
cmb-s4-the next-generation ground-based cosmic microwave background (cmb) experiment-is set to significantly advance the sensitivity of cmb measurements and enhance our understanding of the origin and evolution of the universe. among the science cases pursued with cmb-s4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. this work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of galactic foregrounds and gravitational lensing of the cmb. this framework is unique in its direct use of information from the achieved performance of current stage 2-3 cmb experiments to robustly forecast the science reach of upcoming cmb-polarization endeavors. the methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. to form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. we document multiple rounds of forecasts for cmb-s4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% cl. | cmb-s4: forecasting constraints on primordial gravitational waves |
we present a full λ cdm analysis of the boss dr12 dataset, including information from the power spectrum multipoles, the real-space power spectrum, the reconstructed power spectrum and the bispectrum monopole. this is the first analysis to feature a complete treatment of the galaxy bispectrum, including a consistent theoretical model and without large-scale cuts. unlike previous works, the statistics are measured using window-free estimators: this greatly reduces computational costs by removing the need to window-convolve the theory model. our pipeline is tested using a suite of high-resolution mocks and shown to be robust and precise, with systematic errors far below the statistical thresholds. inclusion of the bispectrum yields consistent parameter constraints and shrinks the σ8 posterior by 13% to reach <5 % precision; less conservative analysis choices would reduce the error bars further. our constraints are broadly consistent with planck: in particular, we find h0=69.6-1.3+1.1 km s-1 mpc-1 , σ8=0.69 2-0.041+0.035 and ns=0.87 0-0.064+0.067, including a bbn prior on the baryon density. when ns is set by planck, we find h0=68.3 1-0.86+0.83 km s-1 mpc-1 and σ8=0.72 2-0.036+0.032. our s8 posterior, 0.751 ±0.039 , is consistent with weak lensing studies, but lower than planck. constraints on the higher-order bias parameters are significantly strengthened from the inclusion of the bispectrum, and we find no evidence for deviation from the dark matter halo bias relations. these results represent the most complete full-shape analysis of boss dr12 to-date, and the corresponding spectra will enable a variety of beyond-λ cdm analyses, probing phenomena such as the neutrino mass and primordial non-gaussianity. | boss dr12 full-shape cosmology: λ cdm constraints from the large-scale galaxy power spectrum and bispectrum monopole |
the effective field theory of large-scale structure is a formalism that allows us to predict the clustering of cosmological large-scale structure in the mildly non-linear regime in an accurate and reliable way. after validating our technique against several sets of numerical simulations, we perform the analysis for the cosmological parameters of the dr12 boss data. we assume λcdm, a fixed value of the baryon/dark-matter ratio, ωb/ωc, and of the tilt of the primordial power spectrum, ns, and no significant input from numerical simulations. by using the one-loop power spectrum multipoles, we measure the primordial amplitude of the power spectrum, as, the abundance of matter, ωm, and the hubble parameter, h0, {to about 13%, 3.2% and 3.2% respectively, obtaining ln (1010as)=2.72± 0.13, 0ωm=0.309± 0.01, h0=68.5± 2.2 km/(s mpc) at 68% confidence level. if we then add a cmb prior on the sound horizon, the error bar on h0 is reduced to 1.6%.} these results are a substantial qualitative and quantitative improvement with respect to former analyses, and suggest that the eftoflss is a powerful instrument to extract cosmological information from large-scale structure. | the cosmological analysis of the sdss/boss data from the effective field theory of large-scale structure |
we present cosmological parameter measurements from the publicly available baryon oscillation spectroscopic survey (boss) data on anisotropic galaxy clustering in fourier space. compared to previous studies, our analysis has two main novel features. first, we use a complete perturbation theory model that properly takes into account the non-linear effects of dark matter clustering, short-scale physics, galaxy bias, redshift-space distortions, and large-scale bulk flows. second, we employ a markov-chain monte-carlo technique and consistently reevaluate the full power spectrum likelihood as we scan over different cosmologies. our baseline analysis assumes minimal λcdm, varies the neutrino masses within a reasonably tight range, fixes the primordial power spectrum tilt, and uses the big bang nucleosynthesis prior on the physical baryon density ωb. in this setup, we find the following late-universe parameters: hubble constant h0=(67.9± 1.1) km s-1mpc-1, matter density fraction ωm=0.295± 0.010, and the mass fluctuation amplitude σ8=0.721± 0.043. these parameters were measured directly from the boss data and independently of the planck cosmic microwave background observations. scanning over the power spectrum tilt or relaxing the other priors do not significantly alter our main conclusions. finally, we discuss the information content of the boss power spectrum and show that it is dominated by the location of the baryon acoustic oscillations and the power spectrum shape. we argue that the contribution of the alcock-paczynski effect is marginal in λcdm, but becomes important for non-minimal cosmological models. | cosmological parameters from the boss galaxy power spectrum |
what are the faintest distant galaxies we can see with the hubble space telescope (hst) now, before the launch of the james webb space telescope? this is the challenge taken up by the frontier fields, a director’s discretionary time campaign with hst and the spitzer space telescope to see deeper into the universe than ever before. the frontier fields combines the power of hst and spitzer with the natural gravitational telescopes of massive high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies ever obtained. six clusters—abell 2744, macsj0416.1-2403, macsj0717.5+3745, macsj1149.5+2223, abell s1063, and abell 370—have been targeted by the hst acs/wfc and wfc3/ir cameras with coordinated parallel fields for over 840 hst orbits. the parallel fields are the second-deepest observations thus far by hst with 5σ point-source depths of ∼29th abmag. galaxies behind the clusters experience typical magnification factors of a few, with small regions magnified by factors of 10-100. therefore, the frontier field cluster hst images achieve intrinsic depths of ∼30-33 mag over very small volumes. spitzer has obtained over 1000 hr of director’s discretionary imaging of the frontier field cluster and parallels in irac 3.6 and 4.5 μm bands to 5σ point-source depths of ∼26.5, 26.0 abmag. we demonstrate the exceptional sensitivity of the hst frontier field images to faint high-redshift galaxies, and review the initial results related to the primary science goals. | the frontier fields: survey design and initial results |
we study the general infrared behavior of the power spectrum of a stochastic gravitational wave background produced by stress tensor in the form bilinear in certain dynamical degrees of freedom. we find ωgw∝k3 for a very wide class of the sources which satisfy a set of reasonable conditions. namely, the k3 scaling is universally valid when the source term is bounded in both frequency and time, is effective in a radiation-dominated stage, and for k smaller than all the physical scales associated with the source, like the peak frequency, peak width, and time duration, etc. we also discuss possible violations of these conditions and their physical implications. | universal infrared scaling of gravitational wave background spectra |
in the conventional misalignment mechanism, the axion field has a constant initial field value in the early universe and later begins to oscillate. we present an alternative scenario where the axion field has a nonzero initial velocity, allowing an axion decay constant much below the conventional prediction from axion dark matter. this axion velocity can be generated from explicit breaking of the axion shift symmetry in the early universe, which may occur as this symmetry is approximate. | axion kinetic misalignment mechanism |
since the discovery of the first fast radio burst (frb) in 2007, and their confirmation as an abundant extragalactic population in 2013, the study of these sources has expanded at an incredible rate. in our 2019 review on the subject, we presented a growing, but still mysterious, population of frbs—60 unique sources, 2 repeating frbs, and only 1 identified host galaxy. however, in only a few short years, new observations and discoveries have given us a wealth of information about these sources. the total frb population now stands at over 600 published sources, 24 repeaters, and 19 host galaxies. higher time resolution data, sustained monitoring, and precision localisations have given us insight into repeaters, host galaxies, burst morphology, source activity, progenitor models, and the use of frbs as cosmological probes. the recent detection of a bright frb-like burst from the galactic magnetar sgr 1935 + 2154 provides an important link between frbs and magnetars. there also continue to be surprising discoveries, like periodic modulation of activity from repeaters and the localisation of one frb source to a relatively nearby globular cluster associated with the m81 galaxy. in this review, we summarise the exciting observational results from the past few years. we also highlight their impact on our understanding of the frb population and proposed progenitor models. we build on the introduction to frbs in our earlier review, update our readers on recent results, and discuss interesting avenues for exploration as the field enters a new regime where hundreds to thousands of new frbs will be discovered and reported each year. | fast radio bursts at the dawn of the 2020s |
a new swampland criterion has recently been proposed. as a consequence, it forbids the existence of de sitter solutions in a low energy effective theory of a quantum gravity. however, there exist classical de sitter solutions of ten-dimensional (10d) type ii supergravities, even though they are unstable. this appears at first sight in contradiction with the criterion. beyond possible doubts on the validity of these solutions, we propose two answers to this apparent puzzle. a first possibility is that the known 10d solutions always exhibit an energy scale of order or higher than a kaluza-klein scale, as we argue. a corresponding 4d low energy effective theory would then differ from the usual consistent truncations, and as we explain, would not admit a de sitter solution. this would reconcile the existence of these 10d de sitter solutions with the 4d criterion. a second, alternative possibility is to have a refined swampland criterion, that we propose. it forbids to have both the existence and the stability of a de sitter solution, while unstable solutions are still allowed. | on the de sitter swampland criterion |
we review the physics and phenomenology of wave dark matter: a bosonic dark matter candidate lighter than about 30 ev. such particles have a de broglie wavelength exceeding the average interparticle separation in a galaxy like the milky way and are, thus, well described as a set of classical waves. we outline the particle physics motivations for such particles, including the quantum chromodynamics axion as well as ultralight axion-like particles such as fuzzy dark matter. the wave nature of the dark matter implies a rich phenomenology: wave interference gives rise to order unity density fluctuations on de broglie scale in halos. one manifestation is vortices where the density vanishes and around which the velocity circulates. there is one vortex ring per de broglie volume on average. for sufficiently low masses, soliton condensation occurs at centers of halos. the soliton oscillates and undergoes random walks, which is another manifestation of wave interference. the halo and subhalo abundance is expected to be suppressed at small masses, but the precise prediction from numerical wave simulations remains to be determined. for ultralight ∼10-22 ev dark matter, the wave interference substructures can be probed by tidal streams or gravitational lensing. the signal can be distinguished from that due to subhalos by the dependence on stream orbital radius or image separation. axion detection experiments are sensitive to interference substructures for wave dark matter that is moderately light. the stochastic nature of the waves affects the interpretation of experimental constraints and motivates the measurement of correlation functions.current constraints and open questions, covering detection experiments and cosmological, galactic, and black hole observations, are discussed. | wave dark matter |
we analyze the power spectrum and the bispectrum of boss galaxy-clustering data using the prediction from the effective field theory of large-scale structure at one-loop order for $\textit{both}$ the power spectrum $\textit{and}$ the bispectrum. with $\lambda$cdm parameters fixed to planck preferred values, we set limits on three templates of non-gaussianities predicted by many inflationary models: the equilateral, the orthogonal, and the local shapes. after validating our analysis against simulations, we find $f_{\rm nl}^{\rm equil.}= 245 \pm 293\, , f_{\rm nl}^{\rm orth.}= -60 \pm 72\, , f_{\rm nl}^{\rm loc.}= 7 \pm 31$, at $68\%$ confidence level. these bispectrum-based constraints from large-scale structure, not far from the ones of wmap, suggest promising results from upcoming surveys. | limits on primordial non-gaussianities from boss galaxy-clustering data |
the recent detection of a stochastic signal in the nanograv 15-year data set has aroused great interest in uncovering its origin. however, the evidence for the hellings-downs correlations, a key signature of the gravitational-wave background (gwb) predicted by general relativity, remains inconclusive. in this letter, we search for an isotropic non-tensorial gwb, allowed by general metric theories of gravity, in the nanograv 15-year data set. our analysis reveals a bayes factor of approximately 2.5, comparing the quadrupolar (tensor transverse, tt) correlations to the scalar transverse (st) correlations, suggesting that the st correlations provide a comparable explanation for the observed stochastic signal in the nanograv data. we obtain the median and the $90\%$ equal-tail amplitudes as $\mathcal{a}_\mathrm{st} = 7.8^{+5.1}_{-3.5} \times 10^{-15}$ at the frequency of 1/year. furthermore, we find that the vector longitudinal (vl) and scalar longitudinal (sl) correlations are weakly and strongly disfavoured by data, respectively, yielding upper limits on the amplitudes: $\mathcal{a}_\mathrm{vl}^{95\%} \lesssim 1.7 \times 10^{-15}$ and $\mathcal{a}_\mathrm{sl}^{95\%} \lesssim 7.4 \times 10^{-17}$. lastly, we fit the nanograv data with the general transverse (gt) correlations parameterized by a free parameter $\alpha$. our analysis yields $\alpha=1.74^{+1.18}_{-1.41}$, thus excluding both the tt ($\alpha=3$) and st ($\alpha=0$) models at the $90\%$ confidence level. | search for non-tensorial gravitational-wave backgrounds in the nanograv 15-year data set |
fast radio bursts (frbs) are brief radio emissions from distant astronomical sources. some are known to repeat, but most are single bursts. nonrepeating frb observations have had insufficient positional accuracy to localize them to an individual host galaxy. we report the interferometric localization of the single-pulse frb 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. the burst has not been observed to repeat. the properties of the burst and its host are markedly different from those of the only other accurately localized frb source. the integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some frbs are clean probes of the baryonic component of the cosmic web. | a single fast radio burst localized to a massive galaxy at cosmological distance |
a new era of exploring the early universe may have begun with the recent strong evidence for the stochastic gravitational wave (gw) background from the data reported by nanograv, epta (including inpta data), ppta, and cpta. inspired by this, we propose a new potential source of stochastic gws in the minimal supersymmetric standard model (mssm), which could be the theory at a very high energy scale. this source is the "axion" field in the higgs multiplets when the higgs field takes a large value along the d-flat direction in the early universe, for example, during inflation. the axion motion triggers the instability of the standard model u(1) and/or su(3) gauge fields, producing stochastic gws during the inflation. this scenario can be seen as a simple uv completion of the commonly studied models where an axion spectator/inflaton is coupled to a hidden u(1) or su(n) gauge field without matter fields. thus the nanohertz gws may be a sign of supersymmetry. primordial magnetic field production is also argued. in addition, we point out the simple possibility that this axion within the mssm drives inflation. | a novel probe of supersymmetry in light of nanohertz gravitational waves |
the einstein telescope (et), the european project for a third-generation gravitational-wave detector, has a reference configuration based on a triangular shape consisting of three nested detectors with 10 km arms, where each detector has a 'xylophone' configuration made of an interferometer tuned toward high frequencies, and an interferometer tuned toward low frequencies and working at cryogenic temperature. here, we examine the scientific perspectives under possible variations of this reference design. we perform a detailed evaluation of the science case for a single triangular geometry observatory, and we compare it with the results obtained for a network of two l-shaped detectors (either parallel or misaligned) located in europe, considering different choices of arm-length for both the triangle and the 2l geometries. we also study how the science output changes in the absence of the low-frequency instrument, both for the triangle and the 2l configurations. we examine a broad class of simple 'metrics' that quantify the science output, related to compact binary coalescences, multi-messenger astronomy and stochastic backgrounds, and we then examine the impact of different detector designs on a more specific set of scientific objectives. | science with the einstein telescope: a comparison of different designs |
litebird, the lite (light) satellite for the study of b-mode polarization and inflation from cosmic background radiation detection, is a space mission for primordial cosmology and fundamental physics. the japan aerospace exploration agency (jaxa) selected litebird in may 2019 as a strategic large-class (l-class) mission, with an expected launch in the late 2020s using jaxa's h3 rocket. litebird is planned to orbit the sun-earth lagrangian point l2, where it will map the cosmic microwave background polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 ghz, to achieve an unprecedented total sensitivity of $2.2\, \mu$k-arcmin, with a typical angular resolution of 0.5○ at 100 ghz. the primary scientific objective of litebird is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. the measurements of litebird will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. we provide an overview of the litebird project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions, and synergies with other projects. | probing cosmic inflation with the litebird cosmic microwave background polarization survey |
we present results from an analysis of all data taken by the bicep2/keck cmb polarization experiments up to and including the 2015 observing season. this includes the first keck array observations at 220 ghz and additional observations at 95 and 150 ghz. the q and u maps reach depths of 5.2, 2.9, and 26 μ kcmb arcmin at 95, 150, and 220 ghz, respectively, over an effective area of ≈400 square degrees. the 220 ghz maps achieve a signal to noise on polarized dust emission approximately equal to that of planck at 353 ghz. we take auto and cross spectra between these maps and publicly available wmap and planck maps at frequencies from 23 to 353 ghz. we evaluate the joint likelihood of the spectra versus a multicomponent model of lensed-λ cdm +r +dust+synchrotron+noise . the foreground model has seven parameters, and we impose priors on some of these using external information from planck and wmap derived from larger regions of sky. the model is shown to be an adequate description of the data at the current noise levels. the likelihood analysis yields the constraint r0.05<0.07 at 95% confidence, which tightens to r0.05<0.06 in conjunction with planck temperature measurements and other data. the lensing signal is detected at 8.8 σ significance. running a maximum likelihood search on simulations we obtain unbiased results and find that σ (r )=0.020 . these are the strongest constraints to date on primordial gravitational waves. | constraints on primordial gravitational waves using planck, wmap, and new bicep2/keck observations through the 2015 season |
we consider all degenerate scalar-tensor theories that depend quadratically on second-order derivatives of a scalar field, which we have identified in a previous work. these theories, whose degeneracy, in general, ensures the absence of ostrogradsky's instability, include the quartic horndeski lagrangian and its quartic extension beyond horndeski, as well as other lagrangians. we study how all these theories transform under general disformal transformations and find that they can be separated into three main classes that are stable under these transformations. this leads to a complete classification modulo disformal transformations. finally, we show that these higher order theories include mimetic gravity and some particular khronometric theories. they also contain theories that do not correspond, to our knowledge, to already studied theories, even up to disformal transformations. | degenerate higher order scalar-tensor theories beyond horndeski and disformal transformations |
this paper investigates whether changes to late-time physics can resolve the 'hubble tension'. it is argued that many of the claims in the literature favouring such solutions are caused by a misunderstanding of how distance ladder measurements actually work and, in particular, by the inappropriate use of a distance ladder h0 prior. a dynamics-free inverse distance ladder shows that changes to late-time physics are strongly constrained observationally and cannot resolve the discrepancy between the sh0es data and the base λcdm cosmology inferred from planck. we propose a statistically rigorous scheme to replace the use of h0 priors. | to h0 or not to h0? |
we derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (bao) measurements with cosmic microwave background (cmb) data and a recent reanalysis of type ia supernova (sn) data. in particular, we take advantage of high-precision bao measurements from galaxy clustering and the lyman-α forest (lyaf) in the sdss-iii baryon oscillation spectroscopic survey (boss). treating the bao scale as an uncalibrated standard ruler, bao data alone yield a high confidence detection of dark energy; in combination with the cmb angular acoustic scale they further imply a nearly flat universe. adding the cmb-calibrated physical scale of the sound horizon, the combination of bao and sn data into an "inverse distance ladder" yields a measurement of h0=67.3 ±1.1 km s-1 mpc-1 , with 1.7% precision. this measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with cmb-based estimates that assume a flat λ cdm cosmology is an important corroboration of this minimal cosmological model. for constant dark energy (λ ), our bao +sn +cmb combination yields matter density ωm=0.301 ±0.008 and curvature ωk=-0.003 ±0.003 . when we allow more general forms of evolving dark energy, the bao +sn +cmb parameter constraints are always consistent with flat λ cdm values at ≈1 σ . while the overall χ2 of model fits is satisfactory, the lyaf bao measurements are in moderate (2 - 2.5 σ ) tension with model predictions. models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher h0 and lower matter clustering amplitude, improving agreement with some low redshift observations. expansion history alone yields an upper limit on the summed mass of neutrino species, ∑mν<0.56 ev (95% confidence), improving to ∑mν<0.25 ev if we include the lensing signal in the planck cmb power spectrum. in a flat λ cdm model that allows extra relativistic species, our data combination yields neff=3.43 ±0.26 ; while the lyaf bao data prefer higher neff when excluding galaxy bao, the galaxy bao alone favor neff≈3 . when structure growth is extrapolated forward from the cmb to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates. | cosmological implications of baryon acoustic oscillation measurements |
we develop a mellin space approach to boundary correlation functions in anti-de sitter (ads) and de sitter (ds) spaces. using the mellin-barnes representation of correlators in fourier space, we show that the analytic continuation between adsd+1 and dsd+1 is encoded in a collection of simple relative phases. this allows us to determine the late-time tree-level three-point correlators of spinning fields in dsd+1 from known results for witten diagrams in adsd+1 by multiplication with a simple trigonometric factor. at four point level, we show that conformal symmetry fixes exchange four-point functions both in adsd+1 and dsd+1 in terms of the dual conformal partial wave (which in fourier space is a product of boundary three-point correlators) up to a factor which is determined by the boundary conditions. in this work we focus on late-time four-point correlators with external scalars and an exchanged field of integer spin-ℓ. the mellin-barnes representation makes manifest the analytic structure of boundary correlation functions, providing an analytic expression for the exchange four-point function which is valid for general d and generic scaling dimensions, in particular massive, light and (partially-)massless fields. it moreover naturally identifies boundary correlation functions for generic fields with multi-variable meijer-g functions. when d = 3 we reproduce existing explicit results available in the literature for external conformally coupled and massless scalars. from these results, assuming the weak breaking of the de sitter isometries, we extract the corresponding correction to the inflationary three-point function of general external scalars induced by a general spin- ℓ field at leading order in slow roll. these results provide a step towards a more systematic understanding of de sitter observables at tree level and beyond using mellin space methods. | bootstrapping inflationary correlators in mellin space |
compact steep-spectrum (css) and peaked-spectrum (ps) radio sources are compact, powerful radio sources. the multi-frequency observational properties and current theories are reviewed with emphasis on developments since the earlier review of o'dea (pasp 110:493-532, https://doi.org/10.1086/316162, 1998). there are three main hypotheses for the nature of ps and css sources. (1) the ps sources might be very young radio galaxies which will evolve into css sources on their way to becoming large radio galaxies. (2) the ps and css sources might be compact, because they are confined (and enhanced in radio power) by interaction with dense gas in their environments. (3) alternately, the ps sources might be transient or intermittent sources. each of these hypotheses may apply to individual objects. the relative number in each population will have significant implications for the radio galaxy paradigm. proper motion studies over long time baselines have helped determine hotspot speeds for over three dozen sources and establish that these are young objects. multi-frequency polarization observations have demonstrated that many css/ps sources are embedded in a dense interstellar medium and vigorously interacting with it. the detection of emission line gas aligned with the radio source, and blue-shifted hi absorption, and [oiii] emission lines indicates that agn feedback is present in these objects - possibly driven by the radio source. also, css/ps sources with evidence of episodic agn over a large range of time-scales have been discussed. the review closes with a discussion of open questions and prospects for the future. | compact steep-spectrum and peaked-spectrum radio sources |
in this work we introduce a new theoretical framework for einstein-gauss-bonnet theories of gravity, which results to particularly elegant, functionally simple and transparent gravitational equations of motion, slow-roll indices and the corresponding observational indices. the main requirement is that the einstein-gauss-bonnet theory has to be compatible with the gw170817 event, so the gravitational wave speed ct2 is required to be ct2 ≃ 1 in natural units. this assumption was also made in a previous work of ours, but in this work we express all the related quantities as functions of the scalar field. the constraint ct2 ≃ 1 restricts the functional form of the scalar gauss-bonnet coupling function ξ (ϕ) and of the scalar potential v (ϕ), which must satisfy a differential equation. however, by also assuming that the slow-roll conditions hold true, the resulting equations of motion and the slow-roll indices acquire particularly simple forms, and also the relation that yields the e-foldings number is n =∫ ϕi ϕf/ξ″ /ξ‧ dϕ, a fact that enables us to perform particularly simple calculations in order to study the inflationary phenomenological implications of several models. as it proves, the models we presented are compatible with the observational data, and also satisfy all the assumptions made during the process of extracting the gravitational equations of motion. more interestingly, we also investigated the phenomenological implications of an additional condition ξ‧ /ξ″ ≪ 1, which is motivated by the slow-roll conditions that are imposed on the scalar field evolution and on the hubble rate. as we shall show, the resulting constraint differential equation that constrains the functional form of the scalar gauss-bonnet coupling function ξ (ϕ) and of the scalar potential v (ϕ), is simpler in this case, and in effect the whole study becomes somewhat easier. as we also show, compatibility with the observational data can also be achieved in this case too, in a much simpler and less constrained way. our approach opens a new window in viable einstein-gauss-bonnet theories of gravity. | rectifying einstein-gauss-bonnet inflation in view of gw170817 |
we study the cosmological effects of two-body dark matter decays in which the products of the decay include a massless and a massive particle. we show that if the massive daughter particle is slightly warm it is possible to relieve the tension between distance ladder measurements of the present-day hubble parameter with measurements from the cosmic microwave background. | dark matter decaying in the late universe can relieve the h0 tension |
we perform a bayesian search in the latest pulsar timing array (pta) datasets for a stochastic gravitational wave (gw) background sourced by curvature perturbations at scales 10^5105 mpc^{-1}\lesssim−1≲ k\lesssim 10^8≲108 mpc^{-1}−1. these re-enter the hubble horizon at temperatures around and below the qcd crossover phase transition in the early universe. we include a stochastic background of astrophysical origin in our search and properly account for constraints on the curvature power spectrum from the overproduction of primordial black holes (pbhs). we find that the international pta data release 2 significantly favors the astrophysical model for its reported common-spectrum process, over the curvature-induced background. on the other hand, the two interpretations fit the nanograv 12.5 years dataset equally well. we then set new upper limits on the amplitude of the curvature power spectrum at small scales. these are independent from, and competitive with, indirect astrophysical bounds from the abundance of pbh dark matter. upcoming pta data releases will provide the strongest probe of the curvature power spectrum around the qcd epoch. | search for scalar induced gravitational waves in the international pulsar timing array data release 2 and nanograv 12.5 years datasets |
the indirect detection of dark matter annihilation and decay using observations of photons, charged cosmic rays and neutrinos offers a promising means of identifying the particle nature of this elusive component of the universe. the last decade has seen substantial advances in observational data-sets, complemented by new insights from numerical simulations, which together have enabled for the first time strong constraints on dark matter particle models, and have revealed several intriguing hints of possible signals. this review provides an introduction to indirect detection methods and an overview of recent results in the field. | a review of indirect searches for particle dark matter |
the search for particle-like dark matter with mev-to-gev masses has developed rapidly in the past few years. we summarize the science case for these searches, the recent progress, and the exciting upcoming opportunities. funding for research and development and a portfolio of small dark matter projects will allow the community to capitalize on the substantial recent advances in theory and experiment and probe vast regions of unexplored dark-matter parameter space in the coming decade. | snowmass2021 cosmic frontier: the landscape of low-threshold dark matter direct detection in the next decade |
we analyze rest-frame ultraviolet to optical spectra of three $z\simeq7.47$ - $7.75$ galaxies whose ly$\alpha$-emission lines were previously detected with keck/mosfire observations, using the jwst/nirspec observations from the cosmic evolution early release science (ceers) survey. from nirspec data, we confirm the systemic redshifts of these ly$\alpha$ emitters, and emission-line ratio diagnostics indicate these galaxies were highly ionized and metal poor. we investigate ly$\alpha$ line properties, including the line flux, velocity offset, and spatial extension. for the one galaxy where we have both nirspec and mosfire measurements, we find a significant offset in their flux measurements ($\sim5\times$ greater in mosfire) and a marginal difference in the velocity shifts. the simplest interpretation is that the ly$\alpha$ emission is extended and not entirely encompassed by the nirspec slit. the cross-dispersion profiles in nirspec reveal that ly$\alpha$ in one galaxy is significantly more extended than the non-resonant emission lines. we also compute the expected sizes of ionized bubbles that can be generated by the ly$\alpha$ sources, discussing viable scenarios for the creation of sizable ionized bubbles ($>$1 physical mpc). the source with the highest-ionization condition is possibly capable of ionizing its own bubble, while the other two do not appear to be capable of ionizing such a large region, requiring additional sources of ionizing photons. therefore, the fact that we detect ly$\alpha$ from these galaxies suggests diverse scenarios on escape of ly$\alpha$ during the epoch of reionization. high spectral resolution spectra with jwst/nirspec will be extremely useful for constraining the physics of patchy reionization. | ceers: diversity of lyman-alpha emitters during the epoch of reionization |
dampe satellite has directly measured the cosmic ray proton spectrum from 40 gev to 100 tev and revealed a new feature at about 13.6 tev.the precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the milky way. this work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 gev to 100 tev, with 21/2years of data recorded by the dark matter particle explorer (dampe). this is the first time that an experiment directly measures the cosmic ray protons up to ~100 tev with high statistics. the measured spectrum confirms the spectral hardening at ~300 gev found by previous experiments and reveals a softening at ~13.6 tev, with the spectral index changing from ~2.60 to ~2.85. our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of galactic cosmic rays. | measurement of the cosmic ray proton spectrum from 40 gev to 100 tev with the dampe satellite |
flat $\lambda$cdm cosmology is specified by two constant fitting parameters in the late universe, the hubble constant $h_0$ and matter density (today) $\omega_m$. in the cosmology literature, one typically \textit{assumes} that there is no redshift evolution of cosmological parameters when one fits data sets. here, in mock observational hubble data we demonstrate evolution in distributions of best fit parameters with effective redshift. as a result, considerably different $(h_0, \omega_m)$ best fits from planck-$\lambda$cdm cannot be precluded in high redshift bins. we explore if observational hubble data, type ia supernovae and standardisable quasar samples exhibit redshift evolution of best fit $\lambda$cdm parameters. in all samples, we confirm an increasing $\omega_m$ (decreasing $h_0$) trend with increasing bin redshift. through comparison with mocks, we confirm that similar behaviour can arise randomly within the flat $\lambda$cdm model with probabilities as low as $p = 0.0021$ ($3.1 \, \sigma$). | putting flat $\\lambda$cdm in the (redshift) bin |
with the advent of gravitational-wave astronomy marked by the aligo gw150914 and gw151226 observations, a measurement of the cosmological speed of gravity will likely soon be realised. we show that a confirmation of equality to the speed of light as indicated by indirect galactic observations will have important consequences for a very large class of alternative explanations of the late-time accelerated expansion of our universe. it will break the dark degeneracy of self-accelerated horndeski scalar-tensor theories in the large-scale structure that currently limits a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy. signatures of a self-acceleration must then manifest in the linear, unscreened cosmological structure. we describe the minimal modification required for self-acceleration with standard gravitational-wave speed and show that its maximum likelihood yields a 3σ poorer fit to cosmological observations compared to a cosmological constant. hence, equality between the speeds challenges the concept of cosmic acceleration from a genuine scalar-tensor modification of gravity. | challenges to self-acceleration in modified gravity from gravitational waves and large-scale structure |
we perform a comprehensive study of milky way (mw) satellite galaxies to constrain the fundamental properties of dark matter (dm). this analysis fully incorporates inhomogeneities in the spatial distribution and detectability of mw satellites and marginalizes over uncertainties in the mapping between galaxies and dm halos, the properties of the mw system, and the disruption of subhalos by the mw disk. our results are consistent with the cold, collisionless dm paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. at 95% confidence, we report limits on (i) the mass of thermal relic warm dm, mwdm>6.5 kev (free-streaming length, λfs≲10 h-1 kpc ), (ii) the velocity-independent dm-proton scattering cross section, σ0<8.8 ×10-29 cm2 for a 100 mev dm particle mass [dm-proton coupling, cp≲(0.3 gev )-2], and (iii) the mass of fuzzy dm, mϕ>2.9 ×10-21 ev (de broglie wavelength, λdb≲0.5 kpc ). these constraints are complementary to other observational and laboratory constraints on dm properties. | constraints on dark matter properties from observations of milky way satellite galaxies |
we study the formation of primordial black holes (pbhs) in strongly super-cooled first-order phase transitions. the mechanism is based on the presence of remnants dominated by the false vacuum that scale slower with the expansion of the universe than their surroundings where this energy was already converted into radiation. we compute the pbh formation from these remnants including the contribution from the false vacuum and the bubble walls, by estimating the collapse using the hoop conjecture and by considering both regions collapsing immediately when entering the horizon and sub-horizon regions that collapse as their compactness grows. we show that for exponential bubble nucleation rate, γ ∝ eβt, the primordial black hole formation implies β/h ≳ 3.8, where h denotes the hubble rate, if the potential energy of the false vacuum is ∆v ≲ (1012 gev)4, as otherwise a too large abundance of long-lived pbhs forms. the observed dark matter abundance can be formed in asteroid mass pbhs if β/h ≃ 3.8 and 105 gev ≲ ∆v1/4 ≲ 108 gev. finally, we consider also the effect of the second order correction to the exponential nucleation rate showing that the pbh abundance is mainly determined by the average radius of the true vacuum bubbles. | primordial black holes from strong first-order phase transitions |
we review several current aspects of dark matter theory and experiment. we overview the present experimental status, which includes current bounds and recent claims and hints of a possible signal in a wide range of experiments: direct detection in underground laboratories, gamma-ray, cosmic ray, x-ray, neutrino telescopes, and the lhc. we briefly review several possible particle candidates for a weakly interactive massive particle (wimp) and dark matter that have recently been considered in the literature. we pay particular attention to the lightest neutralino of supersymmetry as it remains the best motivated candidate for dark matter and also shows excellent detection prospects. finally we briefly review some alternative scenarios that can considerably alter properties and prospects for the detection of dark matter obtained within the standard thermal wimp paradigm. | wimp dark matter candidates and searches—current status and future prospects |
in a growing number of galaxy clusters diffuse extended radio sources have been found. these sources are not directly associated with individual cluster galaxies. the radio emission reveal the presence of cosmic rays and magnetic fields in the intracluster medium (icm). we classify diffuse cluster radio sources into radio halos, cluster radio shocks (relics), and revived agn fossil plasma sources. radio halo sources can be further divided into giant halos, mini-halos, and possible "intermediate" sources. halos are generally positioned at cluster center and their brightness approximately follows the distribution of the thermal icm. cluster radio shocks (relics) are polarized sources mostly found in the cluster's periphery. they trace merger induced shock waves. revived fossil plasma sources are characterized by their radio steep-spectra and often irregular morphologies. in this review we give an overview of the properties of diffuse cluster radio sources, with an emphasis on recent observational results. we discuss the resulting implications for the underlying physical acceleration processes that operate in the icm, the role of relativistic fossil plasma, and the properties of icm shocks and magnetic fields. we also compile an updated list of diffuse cluster radio sources which will be available on-line (http://galaxyclusters.com). we end this review with a discussion on the detection of diffuse radio emission from the cosmic web. | diffuse radio emission from galaxy clusters |
recently, pulsar timing array (pta) collaborations announced evidence for an isotropic stochastic gravitational wave (gw) background. the origin of the pta signal can be astrophysical or cosmological. in the latter case, the so-called secondary scalar-induced gw scenario is one of the viable explanations, but it has a potentially serious issue of the overproduction of primordial black holes (pbhs) due to the enhanced curvature perturbation. in this letter, we present a new interpretation of the pta signal. namely, it is originated from an extra spectator tensor field that exists on top of the metric tensor perturbation. as the energy density of the extra tensor field is always subdominant, it cannot lead to the formation of pbhs. thus our primordial-tensor-induced scenario is free from the pbh overproduction issue. | extra-tensor-induced origin for the pta signal: no primordial black hole production |
recently the international pulsar timing array collaboration has announced the first strong evidence for an isotropic gravitational wave background (gwb). we propose that rapid small oscillations (wiggles) in the hubble parameter would trigger a resonance with the propagating gravitational waves, leaving novel signature in the gwb spectrum in the form of sharp resonance peaks. the proposed signal can appear at all frequency ranges and is common to continuous spectrum gwbs with arbitrary origin. due to its resonant nature, the signal strength differs by a perturbation order depending on whether the gwb is primordial or not, which makes it a smoking gun for the primordial origin of the observed gwb. we show that a large part of the parameter space of such signal can be constrained by near future pta observations, while fitting the signal template to the current nanograv 15yr data already hints an interesting feature near 15 nhz. | can the gravitational wave background feel wiggles in spacetime? |
motivated by the recent release of new results from five different pulsar timing array (pta) experiments claiming to have found compelling evidence for primordial gravitational waves (gw) at nano-hz frequencies, we consider the prospects of generating such a signal from inflationary blue-tilted tensor power spectrum in a specific dark matter (dm) scenario dubbed as $\textit{miracle-less wimp}$. while $\textit{miracle-less wimp}$, due to insufficient interaction rate with the standard model (sm) bath gets thermally overproduced, inflationary blue-tilted gravitational waves (bgw) in compliance with pta data, conflict cosmological observations if reheat temperature after inflation is sufficiently high. both these issues are circumvented with late entropy dilution, bringing dm abundance within observational limits and creating a doubly-peaked feature in the bgw spectrum consistent with cosmological observations. the blue-tilted tail of the low-frequency peak can fit nanograv 15 yr data, while other parts of the spectrum are within reach of present and future gw experiments. | imprint of inflationary gravitational waves and wimp dark matter in pulsar timing array data |
gravitational wave signal offers a promising window into the dynamics of the early universe. the recent results from pulsar timing arrays (ptas) could be the first glimpse of such new physics. in particular, they could point to new details during the inflation, which can not be probed by other means. we explore the possibility that the new results could come from the secondary gravitational wave sourced by curvature perturbations, generated by a first-order phase transition during the inflation. based on the results of a field-theoretic lattice simulation of the phase transition process, we show that the gravitational wave signal generated through this mechanism can account for the new results from the ptas. we analyze the spectral shape of the signal in detail. future observations can use such information to distinguish the gravitational wave signal considered here from other possible sources. | phase transition during inflation and the gravitational wave signal at pulsar timing arrays |
we propose a type ii seesaw model for light dirac neutrinos to provide an explanation for the recently reported anomaly in w boson mass by the cdf collaboration with 7σ statistical significance. in the minimal model, the required enhancement in w boson mass is obtained at tree level due to the vacuum expectation value of a real scalar triplet, which also plays a role in generating light dirac neutrino mass. depending upon the couplings and masses of newly introduced particles, we can have thermally or non-thermally generated relativistic degrees of freedom δneff in the form of right handed neutrinos which can be observed at future cosmology experiments. extending the model to a radiative dirac seesaw scenario can also accommodate dark matter and lepton anomalous magnetic moment. | type ii dirac seesaw with observable δneff in the light of w-mass anomaly |
the γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (igrb). the igrb comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual galactic foregrounds that are approximately isotropic. the first igrb measurement with the large area telescope (lat) on board the fermi gamma-ray space telescope (fermi) used 10 months of sky-survey data and considered an energy range between 200 mev and 100 gev. improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse galactic emission (dge), and a longer data accumulation of 50 months allow for a refinement and extension of the igrb measurement with the lat, now covering the energy range from 100 mev to 820 gev. the igrb spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) gev using our baseline dge model. the total intensity attributed to the igrb is (7.2 ± 0.6) × 10-6 cm-2 s-1 sr-1 above 100 mev, with an additional +15%/-30% systematic uncertainty due to the galactic diffuse foregrounds. | the spectrum of isotropic diffuse gamma-ray emission between 100 mev and 820 gev |
given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. the planck data shows an unmistakably red, quasi scale-invariant, purely adiabatic primordial power spectrum and no primary non-gaussianities. while these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. such models face many problems, both of the purely theoretical kind, such as the necessity of violating the nec and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. we provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. for example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-gaussianities often result. we highlight several promising attempts to violate the nec without introducing dangerous instabilities at the classical and/or quantum level. if primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. we conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. the constraints and lessons learned as laid out in this review might guide future research. | a critical review of classical bouncing cosmologies |
the nanograv collaboration has recently published strong evidence for a stochastic common-spectrum process that may be interpreted as a stochastic gravitational wave background. we show that such a signal can be explained by second-order gravitational waves produced during the formation of primordial black holes from the collapse of sizeable scalar perturbations generated during inflation. this possibility has two predictions: (i) the primordial black holes may comprise the totality of the dark matter with the dominant contribution to their mass function falling in the range (10-15÷10-11)m⊙ and (ii) the gravitational wave stochastic background will be seen as well by the laser interferometer space antenna experiment. | nanograv data hints at primordial black holes as dark matter |
this article presents an analysis and the resulting limits on light dark matter inelastically scattering off of electrons, and on dark photon and axionlike particle absorption, using a second-generation supercdms high-voltage ev-resolution detector. the 0.93 g si detector achieved a 3 ev phonon energy resolution; for a detector bias of 100 v, this corresponds to a charge resolution of 3% of a single electron-hole pair. the energy spectrum is reported from a blind analysis with 1.2 g-days of exposure acquired in an above-ground laboratory. with charge carrier trapping and impact ionization effects incorporated into the dark matter signal models, the dark matter-electron cross section σ¯e is constrained for dark matter masses from 0.5 to 104 mev /c2; in the mass range from 1.2 to 50 ev /c2 the dark photon kinetic mixing parameter ɛ and the axioelectric coupling constant ga e are constrained. the minimum 90% confidence-level upper limits within the above-mentioned mass ranges are σ¯ e=8.7 ×10-34 cm2 , ɛ =3.3 ×10-14 , and ga e=1.0 ×10-9 . | constraints on low-mass, relic dark matter candidates from a surface-operated supercdms single-charge sensitive detector |
a novel mechanism for the primordial black hole (pbh) production is proposed as a natural and inevitable consequence of general first-order phase transitions without reference to specific underlying particle physics models. we obtain mutual predictions and constraints between primordial black holes and gravitational waves from phase transitions in the general case. for particular interest, our pbhs generated during a pev-scale phase transition could make up all the dark matter, while pbhs generated during a mev-scale phase transition could simultaneously account for ligo-virgo coalescence events and nanograv 12.5-yr result for the corresponding gravitational waves. | primordial black hole production during first-order phase transitions |
we propose a novel primordial black hole (pbh) formation mechanism based on a first-order phase transition (fopt). if a fermion species gains a huge mass in the true vacuum, the corresponding particles get trapped in the false vacuum as they do not have sufficient energy to penetrate the bubble wall. after the fopt, the fermions are compressed into the false vacuum remnants to form non-topological solitons called fermi-balls, and then collapse to pbhs due to the yukawa attractive force. we derive the pbh mass and abundance, showing that for a o (gev) fopt the pbhs could be ∼1017 g and explain all of dark matter. if the fopt happens at higher scale, pbhs are typically overproduced and extra dilution mechanism is necessary to satisfy current constraints. | primordial black holes from a cosmic phase transition: the collapse of fermi-balls |
we present a detailed overview of the cosmological surveys that we aim to carry out with phase 1 of the square kilometre array (ska1) and the science that they will enable. we highlight three main surveys: a medium-deep continuum weak lensing and low-redshift spectroscopic hi galaxy survey over 5 000 deg2; a wide and deep continuum galaxy and hi intensity mapping (im) survey over 20 000 deg2 from $z = 0.35$ to 3; and a deep, high-redshift hi im survey over 100 deg2 from $z = 3$ to 6. taken together, these surveys will achieve an array of important scientific goals: measuring the equation of state of dark energy out to $z ∼ 3$ with percent-level precision measurements of the cosmic expansion rate; constraining possible deviations from general relativity on cosmological scales by measuring the growth rate of structure through multiple independent methods; mapping the structure of the universe on the largest accessible scales, thus constraining fundamental properties such as isotropy, homogeneity, and non-gaussianity; and measuring the hi density and bias out to $z = 6$ . these surveys will also provide highly complementary clustering and weak lensing measurements that have independent systematic uncertainties to those of optical and near-infrared (nir) surveys like euclid, lsst, and wfirst leading to a multitude of synergies that can improve constraints significantly beyond what optical or radio surveys can achieve on their own. this document, the 2018 red book, provides reference technical specifications, cosmological parameter forecasts, and an overview of relevant systematic effects for the three key surveys and will be regularly updated by the cosmology science working group in the run up to start of operations and the key science programme of ska1. | cosmology with phase 1 of the square kilometre array red book 2018: technical specifications and performance forecasts |
recently, pulsar timing array (pta) experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background (sgwb). in this work, we demonstrated that cosmic string loops generated from cosmic global strings offer a viable explanation for the observed nanohertz sgwb data, requiring a cosmic string tension parameter of log(gμ) ∼ −12 and a loop number density of log n ∼ 4. additionally, we revisited the impact of cosmic string loops on the abundance of massive galaxies at high redshifts. however, our analysis revealed challenges in identifying a consistent parameter space that can concurrently explain both the sgwb data and observations from the james webb space telescope. this indicates the necessity for either extending the existing model employed in this research or acknowledging distinct physical origins for these two phenomena. | the nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies |
pulsar timing arrays (ptas) are galactic-scale gravitational wave (gw) detectors. each individual arm, composed of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can be used to extract low-frequency gw signals. we present a noise and sensitivity analysis to accompany the nanograv 15 yr data release and associated papers, along with an in-depth introduction to pta noise models. as a first step in our analysis, we characterize each individual pulsar data set with three types of white-noise parameters and two red-noise parameters. these parameters, along with the timing model and, particularly, a piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the low-frequency gw band we are searching. we tabulate information for all of the pulsars in this data release and present some representative sensitivity curves. we then combine the individual pulsar sensitivities using a signal-to-noise ratio statistic to calculate the global sensitivity of the pta to a stochastic background of gws, obtaining a minimum noise characteristic strain of 7 × 10-15 at 5 nhz. a power-law-integrated analysis shows rough agreement with the amplitudes recovered in nanograv's 15 yr gw background analysis. while our phenomenological noise model does not model all known physical effects explicitly, it provides an accurate characterization of the noise in the data while preserving sensitivity to multiple classes of gw signals. | the nanograv 15 yr data set: detector characterization and noise budget |
this is a transcript of a talk that i gave in cambridge on 17th july 2020 on the `hubble tension'. i review the sh0es analyses by riess and collaborators and point out some internal inconsistencies, including a discrepancy between the relative distances inferred from cepheids of two of the primary geometric distance anchors, the large magellanic cloud (lmc) and ngc 4258. i then ask `what would it take to make sh0es compatible with early time measurements?'. the answer is a systematic bias of 0.1 - 0.15 mag in the intercept of the cepheid period-luminosity relations of sh0es galaxies. such a bias resolves the hubble tension, the tension between the distance anchors, and the difference between sh0es and the tip of the red giant branch (trgb) distance ladder, as measured and calibrated by freedman and collaborators. i show that the difference between the trgb and sh0es values of h0 is caused mainly by a systematic calibration offset. in the short term, observational efforts should be focussed on improving the calibrations of the distance anchors and nearby galaxies, rather than trying to measure distance moduli to more supernovae host galaxies. i argue that an independent distance estimate to ngc 4258 is particularly critical. with such observations, it should be possible, on a relatively short timescale, to establish definitively whether the hubble tension really exists. | a lockdown perspective on the hubble tension (with comments from the sh0es team) |
this review describes recent developments related to the unified model of active galactic nuclei (agns). it focuses on new ideas about the origin and properties of the central obscurer (torus) and the connection to its surroundings. the review does not address radio unification. agn tori must be clumpy but uncertainties about their properties persist. today's most promising models involve disk winds of various types and hydrodynamic simulations that link the large-scale galactic disk to the inner accretion flow. infrared (ir) studies greatly improved our understanding of the spectral energy distribution of agns, but they are hindered by various selection effects. x-ray samples are more complete. the dependence of the covering factor of the torus on luminosity is a basic relationship that remains unexplained. there is also much confusion regarding real type-ii agns, which do not fit into a simple unification scheme. the most impressive recent results are due to ir interferometry, which is not in accord with most torus models, and the accurate mapping of central ionization cones. agn unification may not apply to merging systems and is possibly restricted to secularly evolving galaxies. | revisiting the unified model of active galactic nuclei |
the fourth catalog of active galactic nuclei (agns) detected by the fermi gamma-ray space telescope large area telescope (4lac) between 2008 august 4 and 2016 august 2 contains 2863 objects located at high galactic latitudes (|b| > 10°). it includes 85% more sources than the previous 3lac catalog based on 4 yr of data. agns represent at least 79% of the high-latitude sources in the fourth fermi-large area telescope source catalog (4fgl), which covers the energy range from 50 mev to 1 tev. in addition, 344 gamma-ray agns are found at low galactic latitudes. most of the 4lac agns are blazars (98%), while the remainder are other types of agns. the blazar population consists of 24% flat spectrum radio quasars (fsrqs), 38% bl lac-type objects, and 38% blazar candidates of unknown types (bcus). on average, fsrqs display softer spectra and stronger variability in the gamma-ray band than bl lacs do, confirming previous findings. all agns detected by ground-based atmospheric cerenkov telescopes are also found in the 4lac. | the fourth catalog of active galactic nuclei detected by the fermi large area telescope |
the xenon1t experiment is currently in the commissioning phase at the laboratori nazionali del gran sasso, italy. in this article we study the experiment's expected sensitivity to the spin-independent wimp-nucleon interaction cross section, based on monte carlo predictions of the electronic and nuclear recoil backgrounds. the total electronic recoil background in 1 tonne fiducial volume and (1, 12) kev electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80 ± 0.15) · 10-4 (kg·day·kev)-1, mainly due to the decay of 222rn daughters inside the xenon target. the nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) kev, is composed of (0.6 ± 0.1) (t·y)-1 from radiogenic neutrons, (1.8 ± 0.3) · 10-2 (t·y)-1 from coherent scattering of neutrinos, and less than 0.01 (t·y)-1 from muon-induced neutrons. the sensitivity of xenon1t is calculated with the profile likelihood ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. we take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. the main contribution comes from the relative scintillation efficiency script leff, which affects both the signal from wimps and the nuclear recoil backgrounds. after a 2 y measurement in 1 t fiducial volume, the sensitivity reaches a minimum cross section of 1.6 · 10-47 cm2 at mχ = 50 gev/c2. | physics reach of the xenon1t dark matter experiment. |
so far, roughly 40 quasars with redshifts greater than z = 6 have been discovered. each quasar contains a black hole with a mass of about one billion solar masses (109 ). the existence of such black holes when the universe was less than one billion years old presents substantial challenges to theories of the formation and growth of black holes and the coevolution of black holes and galaxies. here we report the discovery of an ultraluminous quasar, sdss j010013.02+280225.8, at redshift z = 6.30. it has an optical and near-infrared luminosity a few times greater than those of previously known z > 6 quasars. on the basis of the deep absorption trough on the blue side of the lyman-α emission line in the spectrum, we estimate the proper size of the ionized proximity zone associated with the quasar to be about 26 million light years, larger than found with other z > 6.1 quasars with lower luminosities. we estimate (on the basis of a near-infrared spectrum) that the black hole has a mass of ~1.2 × 1010 , which is consistent with the 1.3 × 1010 derived by assuming an eddington-limited accretion rate. | an ultraluminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30 |
we introduce a family of solutions of einstein's gravity minimally coupled to an anisotropic fluid, describing asymptotically flat black holes with "hair" and a regular horizon. these spacetimes can describe the geometry of galaxies harboring supermassive black holes, and are extensions of einstein clusters to include horizons. they are useful to constrain the environment surrounding astrophysical black holes, using electromagnetic or gravitational-wave observations. we compute the main properties of the geometry, including the corrections to the ringdown stage induced by the external matter and fluxes by orbiting particles. the leading order effect to these corrections is a gravitational-redshift, but gravitational-wave propagation is affected by the galactic potential in a nontrivial way, and may be characterized with future observatories. | black holes in galaxies: environmental impact on gravitational-wave generation and propagation |
the dark energy spectroscopic instrument (desi) embarked on an ambitious 5 yr survey in 2021 may to explore the nature of dark energy with spectroscopic measurements of 40 million galaxies and quasars. desi will determine precise redshifts and employ the baryon acoustic oscillation method to measure distances from the nearby universe to beyond redshift z > 3.5, and employ redshift space distortions to measure the growth of structure and probe potential modifications to general relativity. we describe the significant instrumentation we developed to conduct the desi survey. this includes: a wide-field, 3.°2 diameter prime-focus corrector; a focal plane system with 5020 fiber positioners on the 0.812 m diameter, aspheric focal surface; 10 continuous, high-efficiency fiber cable bundles that connect the focal plane to the spectrographs; and 10 identical spectrographs. each spectrograph employs a pair of dichroics to split the light into three channels that together record the light from 360-980 nm with a spectral resolution that ranges from 2000-5000. we describe the science requirements, their connection to the technical requirements, the management of the project, and interfaces between subsystems. desi was installed at the 4 m mayall telescope at kitt peak national observatory and has achieved all of its performance goals. some performance highlights include an rms positioner accuracy of better than 0.″1 and a median signal-to-noise ratio of 7 of the [o ii] doublet at 8 × 10-17 erg s-1 cm-2 in 1000 s for galaxies at z = 1.4-1.6. we conclude with additional highlights from the on-sky validation and commissioning, key successes, and lessons learned. | overview of the instrumentation for the dark energy spectroscopic instrument |
the current cosmological model requires new physics beyond the standard model of elementary particles and fields, such as dark matter and dark energy. their nature is unknown and so is that of the initial fluctuations in the early universe that led to the creation of the cosmic structure we see today. polarized light of the cosmic microwave background (cmb) may hold the answer to these fundamental questions. here, i discuss two phenomena that could be uncovered in cmb observations. first, if the physics behind dark matter and dark energy violates parity symmetry, their coupling to photons should have rotated the plane of linear polarization as the cmb photons have been travelling for more than 13 billion years. this effect is known as `cosmic birefringence'. a tantalizing hint of such a signal has been found with a statistical significance of 3σ. second, the period of accelerated expansion in the very early universe, called `cosmic inflation', might have produced a stochastic background of primordial gravitational waves (as yet unobserved). these might have been generated by vacuum fluctuations in spacetime or by matter fields and could be measurable in the cmb polarization. the goal of observing these two phenomena will influence how data from future cmb experiments are collected, calibrated and analysed. | new physics from the polarized light of the cosmic microwave background |
we present the results of a search for dark matter weakly interacting massive particles (wimps) in the mass range below 20 gev /c2 using a target of low-radioactivity argon with a 6786.0 kg d exposure. the data were obtained using the darkside-50 apparatus at laboratori nazionali del gran sasso. the analysis is based on the ionization signal, for which the darkside-50 time projection chamber is fully efficient at 0.1 kev ee . the observed rate in the detector at 0.5 kev ee is about 1.5 event /kev ee/kg /d and is almost entirely accounted for by known background sources. we obtain a 90% c.l. exclusion limit above 1.8 gev /c2 for the spin-independent cross section of dark matter wimps on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8 - 6 gev /c2 . | low-mass dark matter search with the darkside-50 experiment |
despite growing interest and extensive effort to search for ultralight dark matter in the form of a hypothetical dark photon, how it fits into a consistent cosmology is unclear. several dark photon dark matter production mechanisms proposed previously are known to have limitations, at least in certain mass regimes of experimental interest. in this paper, we explore a novel mechanism, where a coherently oscillating axionlike field can efficiently transfer its energy density to a dark photon field via a tachyonic instability. the residual axion relic is subsequently depleted via couplings to the visible sector, leaving only the dark photon as dark matter. we ensure that the cosmologies of both the axion and dark photon are consistent with existing constraints. we find that the mechanism works for a broad range of dark photon masses, including those of interest for ongoing experiments and proposed detection techniques. | dark photon dark matter produced by axion oscillations |
jwst has revolutionized the field of extragalactic astronomy with its sensitive and high-resolution infrared view of the distant universe. adding to the new legacy of jwst observations, we present the first nircam imaging data release from the jwst advanced deep extragalactic survey (jades), providing nine filters of infrared imaging of ~25 arcmin2 covering the hubble ultra deep field and portions of great observatories origins deep survey south. utilizing 87 on-sky dual-filter hours of exposure time, these images reveal the deepest ever near-infrared view of this iconic field. we supply carefully constructed nine-band mosaics of the jades bands, as well as matching reductions of five additional bands from the jwst extragalactic medium-band survey. combining with existing hubble space telescope imaging, we provide 23-band space-based photometric catalogs and photometric redshifts for ≈47,500 sources. to promote broad engagement with jades, we have created an interactive fitsmap website to provide an interface for professional researchers and the public to experience these jwst data sets. combined with the first jades nirspec data release, these public jades imaging and spectroscopic data sets provide a new foundation for discoveries of the infrared universe by the worldwide scientific community. | jades initial data release for the hubble ultra deep field: revealing the faint infrared sky with deep jwst nircam imaging |
the origin of high-energy cosmic rays, atomic nuclei that continuously impact earth’s atmosphere, is unknown. because of deflection by interstellar magnetic fields, cosmic rays produced within the milky way arrive at earth from random directions. however, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. we searched for neutrino emission using machine learning techniques applied to 10 years of data from the icecube neutrino observatory. by comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the galactic plane at the 4.5σ level of significance. the signal is consistent with diffuse emission of neutrinos from the milky way but could also arise from a population of unresolved point sources. | observation of high-energy neutrinos from the galactic plane |
pulsar timing data used to provide upper limits on a possible stochastic gravitational wave background (sgwb). however, the nanograv collaboration has recently reported strong evidence for a stochastic common-spectrum process, which we interpret as a sgwb in the framework of cosmic strings. the possible nanograv signal would correspond to a string tension g μ ∈(4 ×10-11,10-10) at the 68% confidence level, with a different frequency dependence from supermassive black hole mergers. the sgwb produced by cosmic strings with such values of g μ would be beyond the reach of ligo, but could be measured by other planned and proposed detectors such as ska, lisa, tianqin, aion-1 km, aedge, einstein telescope, and cosmic explorer. | cosmic string interpretation of nanograv pulsar timing data |
the universal character of the gravitational interaction provided by the equivalence principle motivates a geometrical description of gravity. the standard formulation of general relativity à la einstein attributes gravity to the spacetime curvature, to which we have grown accustomed. however, this perception has masked the fact that two alternative, though equivalent, formulations of general relativity in flat spacetimes exist, where gravity can be fully ascribed either to torsion or to nonmetricity. the latter allows a simpler geometrical formulation of general relativity that is oblivious to the affine spacetime structure. generalizations along this line permit us to generate teleparallel and symmetric teleparallel theories of gravity with exceptional properties. in this work we explore modified gravity theories based on nonlinear extensions of the nonmetricity scalar. after presenting some general properties and briefly studying some interesting background cosmologies (including accelerating solutions with relevance for inflation and dark energy), we analyze the behavior of the cosmological perturbations. tensor perturbations feature a rescaling of the corresponding newton's constant, while vector perturbations do not contribute in the absence of vector sources. in the scalar sector we find two additional propagating modes, hinting that f (q ) theories introduce, at least, 2 additional degrees of freedom. these scalar modes disappear around maximally symmetric backgrounds because of the appearance of an accidental residual gauge symmetry corresponding to a restricted diffeomorphism. we finally discuss the potential strong coupling problems of these maximally symmetric backgrounds caused by the discontinuity in the number of propagating modes. | cosmology in f (q ) geometry |
we study hidden-sector particles at past (cern-hamburg-amsterdam-rome-moscow collaboration and nucal), present (na62, seaquest, and darkquest), and future (longquest) experiments at the high-energy intensity frontier. we focus on exploring the minimal vector portal and the next-to-minimal models in which the productions and decays are decoupled. these next-to-minimal models have mostly been devised to explain experimental anomalies while avoiding existing constraints. we demonstrate that proton fixed-target experiments provide one of the most powerful probes for the mev to few gev mass range of these models, using inelastic dark matter (idm) as an example. we consider an idm model with a small mass splitting that yields the observed dark matter relic abundance, and a scenario with a sizable mass splitting that can also explain the muon g -2 anomaly. we set strong limits based on the cern-hamburg-amsterdam-rome-moscow collaboration and nucal experiments, which come close to excluding idm as a full-abundance thermal dark matter candidate in the mev to gev mass range. we also make projections based on na62, seaquest, and darkquest and update the constraints of the minimal dark photon parameter space. we find that nucal sets the only existing constraint in ε ∼10-8- 10-4 regime, reaching ∼800 mev in dark photon mass due to the resonant enhancement of proton bremsstrahlung production. these studies also motivate longquest, a three-stage retooling of the seaquest experiment with short (≲5 m ), medium (∼5 m ), and long (≳35 m ) baseline tracking stations and detectors as a multipurpose machine to explore new physics. | dark photon and muon g -2 inspired inelastic dark matter models at the high-energy intensity frontier |
we report the first plausible optical electromagnetic counterpart to a (candidate) binary black hole merger. detected by the zwicky transient facility, the electromagnetic flare is consistent with expectations for a kicked binary black hole merger in the accretion disk of an active galactic nucleus [b. mckernan, k. e. s. ford, i. bartos et al., astrophys. j. lett. 884, l50 (2019), 10.3847/2041-8213/ab4886] and is unlikely [<o (0.01 %) )] due to intrinsic variability of this source. the lack of color evolution implies that it is not a supernova and instead is strongly suggestive of a constant temperature shock. other false-positive events, such as microlensing or a tidal disruption event, are ruled out or constrained to be <o (0.1 %) . if the flare is associated with s190521g, we find plausible values of total mass mbbh∼100 m⊙, kick velocity vk∼200 km s-1 at θ ∼6 0 ° in a disk with aspect ratio h /a ∼0.01 (i.e., disk height h at radius a ) and gas density ρ ∼10-10 g cm-3 . the merger could have occurred at a disk migration trap (a ∼700 rg; rg≡g msmbh/c2, where msmbh is the mass of the active galactic nucleus supermassive black hole). the combination of parameters implies a significant spin for at least one of the black holes in s190521g. the timing of our spectroscopy prevents useful constraints on broad-line asymmetry due to an off-center flare. we predict a repeat flare in this source due to a reencountering with the disk in ∼1.6 yr (msmbh/108 m⊙)(a /103rg)3 /2 . | candidate electromagnetic counterpart to the binary black hole merger gravitational-wave event s190521g* |
current cosmological data exhibit a tension between inferences of the hubble constant, h0, derived from early and late-universe measurements. one proposed solution is to introduce a new component in the early universe, which initially acts as "early dark energy" (ede), thus decreasing the physical size of the sound horizon imprinted in the cosmic microwave background (cmb) and increasing the inferred h0. previous ede analyses have shown this model can relax the h0 tension, but the cmb-preferred value of the density fluctuation amplitude, σ8, increases in ede as compared to λ cold dark matter (λ cdm ), increasing tension with large-scale structure (lss) data. we show that the ede model fit to cmb and sh0es data yields scale-dependent changes in the matter power spectrum compared to λ cdm , including 10% more power at k =1 h /mpc . motivated by this observation, we reanalyze the ede scenario, considering lss data in detail. we also update previous analyses by including planck 2018 cmb likelihoods, and perform the first search for ede in planck data alone, which yields no evidence for ede. we consider several data set combinations involving the primary cmb, cmb lensing, supernovae, baryon acoustic oscillations, redshift-space distortions, weak lensing, galaxy clustering, and local distance-ladder data (sh0es). while the ede component is weakly detected (3 σ ) when including the sh0es data and excluding most lss data, this drops below 2 σ when further lss data are included. further, this result is in tension with strong constraints imposed on ede by cmb and lss data without sh0es, which show no evidence for this model. we also show that physical priors on the fundamental scalar field parameters further weaken evidence for ede. we conclude that the ede scenario is, at best, no more likely to be concordant with all current cosmological data sets than λ cdm , and appears unlikely to resolve the h0 tension. | early dark energy does not restore cosmological concordance |
we present new measurements of the free-streaming of warm dark matter (wdm) from lyman-α flux-power spectra. we use data from the medium resolution, intermediate redshift xq-100 sample observed with the x-shooter spectrograph (z =3 - 4.2 ) and the high-resolution, high-redshift sample used in viel et al. (2013) obtained with the hires/mike spectrographs (z =4.2 - 5.4 ). based on further improved modelling of the dependence of the lyman-α flux-power spectrum on the free-streaming of dark matter, cosmological parameters, as well as the thermal history of the intergalactic medium (igm) with hydrodynamical simulations, we obtain the following limits, expressed as the equivalent mass of thermal relic wdm particles. the xq-100 flux power spectrum alone gives a lower limit of 1.4 kev, the re-analysis of the hires/mike sample gives 4.1 kev while the combined analysis gives our best and significantly strengthened lower limit of 5.3 kev (all 2 σ c.l.). the further improvement in the joint analysis is partly due to the fact that the two data sets have different degeneracies between astrophysical and cosmological parameters that are broken when the data sets are combined, and more importantly on chosen priors on the thermal evolution. these results all assume that the temperature evolution of the igm can be modeled as a power law in redshift. allowing for a nonsmooth evolution of the temperature of the igm with sudden temperature changes of up to 5000 k reduces the lower limit for the combined analysis to 3.5 kev. a wdm with smaller thermal relic masses would require, however, a sudden temperature jump of 5000 k or more in the narrow redshift interval z =4.6 - 4.8 , in disagreement with observations of the thermal history based on high-resolution resolution lyman-α forest data and expectations for photo-heating and cooling in the low density igm at these redshifts. | new constraints on the free-streaming of warm dark matter from intermediate and small scale lyman-α forest data |
the nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. the dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. these detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. a next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. this review article presents the science cases for such a detector. | a next-generation liquid xenon observatory for dark matter and neutrino physics |
we present a measurement of the hubble constant made using geometric distance measurements to megamaser-hosting galaxies. we have applied an improved approach for fitting maser data and obtained better distance estimates for four galaxies previously published by the megamaser cosmology project: ugc 3789, ngc 6264, ngc 6323, and ngc 5765b. combining these updated distance measurements with those for the maser galaxies cgcg 074-064 and ngc 4258, and assuming a fixed velocity uncertainty of 250 km s-1 associated with peculiar motions, we constrain the hubble constant to be h0 = 73.9 ± 3.0 km s-1 mpc-1 independent of distance ladders and the cosmic microwave background. this best value relies solely on maser-based distance and velocity measurements, and it does not use any peculiar velocity corrections. different approaches for correcting peculiar velocities do not modify h0 by more than ±1σ, with the full range of best-fit hubble constant values spanning 71.8-76.9 km s-1 mpc-1. we corroborate prior indications that the local value of h0 exceeds the early-universe value, with a confidence level varying from 95% to 99% for different treatments of the peculiar velocities. | the megamaser cosmology project. xiii. combined hubble constant constraints |
the first model independent results obtained by the dama/libra-phase2 experiment are presented. the data have been collected over 6 annual cycles corresponding to a total exposure of 1.13 ton $\times$ yr, deep underground at the gran sasso national laboratory (lngs) of the i.n.f.n. the dama/libra-phase2 apparatus, $\simeq$ 250 kg highly radio-pure nai(tl), profits from a second generation high quantum efficiency photomultipliers and of new electronics with respect to dama/libra-phase1. the improved experimental configuration has also allowed to lower the software energy threshold. new data analysis strategies are presented. the dama/libra-phase2 data confirm the evidence of a signal that meets all the requirements of the model independent dark matter (dm) annual modulation signature, at 9.5 $\sigma$ c.l. in the energy region (1-6) kev. in the energy region between 2 and 6 kev, where data are also available from dama/nai and dama/libra-phase1 (exposure $1.33$ ton $\times$ yr, collected over 14 annual cycles), the achieved c.l. for the full exposure (2.46 ton $\times$ yr) is 12.9 $\sigma$; the modulation amplitude of the single-hit scintillation events is: $(0.0103 \pm 0.0008)$ cpd/kg/kev, the measured phase is $(145 \pm 5)$ days and the measured period is $(0.999 \pm 0.001)$ yr, all these values are well in agreement with those expected for dm particles. no systematics or side reaction able to mimic the exploited dm signature (i.e. to account for the whole measured modulation amplitude and to simultaneously satisfy all the requirements of the signature), has been found or suggested by anyone throughout some decades thus far. | first model independent results from dama/libra-phase2 |
we explore whether nonstandard dark sector physics might be required to solve the existing cosmological tensions. the properties we consider in combination are (a) an interaction between the dark matter and dark energy components and (b) a dark energy equation of state w different from that of the canonical cosmological constant w =-1 . in principle, these two parameters are independent. in practice, to avoid early-time, superhorizon instabilities, their allowed parameter spaces are correlated. moreover, a clear degeneracy exists between these two parameters in the case of cosmic microwave background (cmb) data. we analyze three classes of extended interacting dark energy models in light of the 2019 planck cmb results and cepheid-calibrated local distance ladder h0 measurements of riess et al. (r19), as well as recent baryon acoustic oscillation (bao) and type ia supernovae (sneia) distance data. we find that in quintessence coupled dark energy models, where w >-1 , the evidence for a nonzero coupling between the two dark sectors can surpass the 5 σ significance. moreover, for both planck +bao or planck +sneia , we find a preference for w >-1 at about three standard deviations. quintessence models are, therefore, in excellent agreement with current data when an interaction is considered. on the other hand, in phantom coupled dark energy models, there is no such preference for a nonzero dark sector coupling. all the models we consider significantly raise the value of the hubble constant, easing the h0 tension. in the interacting scenario, the disagreement between planck +bao and r19 is considerably reduced from 4.3 σ in the case of the λ cold dark matter (λ cdm ) model to about 2.5 σ . the addition of low-redshift bao and sneia measurements leaves, therefore, some residual tension with r19 but at a level that could be justified by a statistical fluctuation. bayesian evidence considerations mildly disfavor both the coupled quintessence and phantom models, while mildly favoring a coupled vacuum scenario, even when late-time datasets are considered. we conclude that nonminimal dark energy cosmologies, such as coupled quintessence, phantom, or vacuum models, are still an interesting route toward softening existing cosmological tensions, even when low-redshift datasets and bayesian evidence considerations are taken into account. | nonminimal dark sector physics and cosmological tensions |
context. the assembly history experienced by the milky way is currently being unveiled thanks to the data provided by the gaia mission. it is likely that the globular cluster system of our galaxy has followed a similarly intricate formation path.aims: to constrain this formation path, we explore the link between the globular clusters and the known merging events that the milky way has experienced.methods: to this end, we combined the kinematic information provided by gaia for almost all galactic clusters, with the largest sample of cluster ages available after carefully correcting for systematic errors. to identify clusters with a common origin we analysed their dynamical properties, particularly in the space of integrals of motion.results: we find that about 40% of the clusters likely formed in situ. a similarly large fraction, 35%, appear to be possibly associated to known merger events, in particular to gaia-enceladus (19%), the sagittarius dwarf galaxy (5%), the progenitor of the helmi streams (6%), and to the sequoia galaxy (5%), although some uncertainty remains due to the degree of overlap in their dynamical characteristics. of the remaining clusters, 16% are tentatively associated to a group with high binding energy, while the rest are all on loosely bound orbits and likely have a more heterogeneous origin. the resulting age-metallicity relations are remarkably tight and differ in their detailed properties depending on the progenitor, providing further confidence on the associations made.conclusions: we provide a table listing the likely associations. improved kinematic data by future gaia data releases and especially a larger, systematic error-free sample of cluster ages would help to further solidify our conclusions. | origin of the system of globular clusters in the milky way |
primordial black holes (pbh) have been shown to arise from high peaks in the matter power spectra of multi-field models of inflation. here we show, with a simple toy model, that it is also possible to generate a peak in the curvature power spectrum of single-field inflation. we assume that the effective dynamics of the inflaton field presents a near-inflection point which slows down the field right before the end of inflation and gives rise to a prominent spike in the fluctuation power spectrum at scales much smaller than those probed by cosmic microwave background (cmb) and large scale structure (lss) observations. this peak will give rise, upon reentry during the radiation era, to pbh via gravitational collapse. the mass and abundance of these pbh is such that they could constitute the totality of the dark matter today. we satisfy all cmb and lss constraints and predict a very broad range of pbh masses. some of these pbh are light enough that they will evaporate before structure formation, leaving behind a large curvature fluctuation on small scales. this broad mass distribution of pbh as dark matter will be tested in the future by advligo and lisa interferometers. | primordial black holes from single field models of inflation |
a new realization of the international celestial reference frame (icrf) is presented based on the work achieved by a working group of the international astronomical union (iau) mandated for this purpose. this new realization follows the initial realization of the icrf completed in 1997 and its successor, icrf2, adopted as a replacement in 2009. the new frame, referred to as icrf3, is based on nearly 40 years of data acquired by very long baseline interferometry at the standard geodetic and astrometric radio frequencies (8.4 and 2.3 ghz), supplemented with data collected at higher radio frequencies (24 ghz and dual-frequency 32 and 8.4 ghz) over the past 15 years. state-of-the-art astronomical and geophysical modeling has been used to analyze these data and derive source positions. the modeling integrates, for the first time, the effect of the galactocentric acceleration of the solar system (directly estimated from the data) which, if not considered, induces significant deformation of the frame due to the data span. the new frame includes positions at 8.4 ghz for 4536 extragalactic sources. of these, 303 sources, uniformly distributed on the sky, are identified as "defining sources" and as such serve to define the axes of the frame. positions at 8.4 ghz are supplemented with positions at 24 ghz for 824 sources and at 32 ghz for 678 sources. in all, icrf3 comprises 4588 sources, with three-frequency positions available for 600 of these. source positions have been determined independently at each of the frequencies in order to preserve the underlying astrophysical content behind such positions. they are reported for epoch 2015.0 and must be propagated for observations at other epochs for the most accurate needs, accounting for the acceleration toward the galactic center, which results in a dipolar proper motion field of amplitude 0.0058 milliarcsecond yr-1 (mas yr-1). the frame is aligned onto the international celestial reference system to within the accuracy of icrf2 and shows a median positional uncertainty of about 0.1 mas in right ascension and 0.2 mas in declination, with a noise floor of 0.03 mas in the individual source coordinates. a subset of 500 sources is found to have extremely accurate positions, in the range of 0.03-0.06 mas, at the traditional 8.4 ghz frequency. comparing icrf3 with the recently released gaia celestial reference frame 2 in the optical domain, there is no evidence for deformations larger than 0.03 mas between the two frames, in agreement with the icrf3 noise level. significant positional offsets between the three icrf3 frequencies are detected for about 5% of the sources. moreover, a notable fraction (22%) of the sources shows optical and radio positions that are significantly offset. there are indications that these positional offsets may be the manifestation of extended source structures. this third realization of the icrf was adopted by the iau at its 30th general assembly in august 2018 and replaced the previous realization, icrf2, on january 1, 2019. full tables 10, 11, 12, 14, 15, and 16 are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/644/a159 | the third realization of the international celestial reference frame by very long baseline interferometry |
de sitter solutions have been recently conjectured to be incompatible with quantum gravity. in this paper we critically assess the progress and challenges of different mechanisms to obtain de sitter vacua in string compactifications and compare them to quintessence models. we argue that, despite recent criticisms, de sitter models reached a level of concreteness and calculational control which has been improving over time. on the other hand, building string models of quintessence appears to be more challenging and requires additional fine-tuning. we discuss the tension between the swampland conjecture and the higgs potential and find examples which can evade fifth-force bounds even if they seem very hard to realise in string theory. we also comment on the tension with low-redshift data and explore ultra-light axions from string theory as dark energy candidates. | de sitter vs quintessence in string theory |
uncovering the nature of dark matter is one of the most important goals of particle physics. light bosonic particles, such as the dark photon, are well-motivated candidates: they are generally long-lived, weakly interacting, and naturally produced in the early universe. in this work, we report on light a' multilayer periodic optical snspd target, a proof-of-concept experiment searching for dark photon dark matter in the ev mass range, via coherent absorption in a multilayer dielectric haloscope. using a superconducting nanowire single-photon detector (snspd), we achieve efficient photon detection with a dark count rate of ∼6 ×10-6 counts /s . we find no evidence for dark photon dark matter in the mass range of ∼0.7 - 0.8 ev with kinetic mixing ε ≳10-12, improving existing limits in ε by up to a factor of 2. with future improvements to snspds, our architecture could probe significant new parameter space for dark photon and axion dark matter in the mev to 10 ev mass range. | new constraints on dark photon dark matter with superconducting nanowire detectors in an optical haloscope |
analysis of the planck 2018 data set indicates that the statistical properties of the cosmic microwave background (cmb) temperature anisotropies are in excellent agreement with previous studies using the 2013 and 2015 data releases. in particular, they are consistent with the gaussian predictions of the λcdm cosmological model, yet also confirm the presence of several so-called "anomalies" on large angular scales. the novelty of the current study, however, lies in being a first attempt at a comprehensive analysis of the statistics of the polarization signal over all angular scales, using either maps of the stokes parameters, q and u, or the e-mode signal derived from these using a new methodology (which we describe in an appendix). although remarkable progress has been made in reducing the systematic effects that contaminated the 2015 polarization maps on large angular scales, it is still the case that residual systematics (and our ability to simulate them) can limit some tests of non-gaussianity and isotropy. however, a detailed set of null tests applied to the maps indicates that these issues do not dominate the analysis on intermediate and large angular scales (i.e., ℓ ≲ 400). in this regime, no unambiguous detections of cosmological non-gaussianity, or of anomalies corresponding to those seen in temperature, are claimed. notably, the stacking of cmb polarization signals centred on the positions of temperature hot and cold spots exhibits excellent agreement with the λcdm cosmological model, and also gives a clear indication of how planck provides state-of-the-art measurements of cmb temperature and polarization on degree scales. | planck 2018 results. vii. isotropy and statistics of the cmb |
cmb-hd is a proposed millimeter-wave survey over half the sky that would be ultra-deep (0.5 uk-arcmin) and have unprecedented resolution (15 arcseconds at 150 ghz). such a survey would answer many outstanding questions about the fundamental physics of the universe. major advances would be 1.) the use of gravitational lensing of the primordial microwave background to map the distribution of matter on small scales (k~10 h mpc^(-1)), which probes dark matter particle properties. it will also allow 2.) measurements of the thermal and kinetic sunyaev-zel'dovich effects on small scales to map the gas density and velocity, another probe of cosmic structure. in addition, cmb-hd would allow us to cross critical thresholds: 3.) ruling out or detecting any new, light (< 0.1 ev) particles that were in thermal equilibrium with known particles in the early universe, 4.) testing a wide class of multi-field models that could explain an epoch of inflation in the early universe, and 5.) ruling out or detecting inflationary magnetic fields. cmb-hd would also provide world-leading constraints on 6.) axion-like particles, 7.) cosmic birefringence, 8.) the sum of the neutrino masses, and 9.) the dark energy equation of state. the cmb-hd survey would be delivered in 7.5 years of observing 20,000 square degrees of sky, using two new 30-meter-class off-axis crossed dragone telescopes to be located at cerro toco in the atacama desert. each telescope would field 800,000 detectors (200,000 pixels), for a total of 1.6 million detectors. | snowmass2021 cmb-hd white paper |
we present the most significant measurement of the cosmic microwave background (cmb) lensing potential to date (at a level of 40σ), using temperature and polarization data from the planck 2015 full-mission release. using a polarization-only estimator, we detect lensing at a significance of 5σ. we cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40 ≤ l ≤ 400, and an associated likelihood for cosmological parameter constraints. we find good agreement between our measurement of the lensing potential power spectrum and that found in the λcdm model that best fits the planck temperature and polarization power spectra. using the lensing likelihood alone we obtain a percent-level measurement of the parameter combination σ8ω0.25m = 0.591 ± 0.021. we combine our determination of the lensing potential with the e-mode polarization, also measured by planck, to generate an estimate of the lensing b-mode. we show that this lensing b-mode estimate is correlated with the b-modes observed directly by planck at the expected level and with a statistical significance of 10σ, confirming planck's sensitivity to this known sky signal. we also correlate our lensing potential estimate with the large-scale temperature anisotropies, detecting a cross-correlation at the 3σ level, as expected because of dark energy in the concordance λcdm model. | planck 2015 results. xv. gravitational lensing |
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