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this lecture note provides a generic introduction to reheating after inflation, covering theoretical, phenomenological and observational aspects of the process. | lectures on reheating after inflation |
even if massive (10 m⊙≲m ≲104m⊙ ) primordial black holes (pbhs) can only account for a small fraction of the dark matter (dm) in the universe, they may still be responsible for a sizable fraction of the coalescence events measured by ligo/virgo, and/or act as progenitors of the supermassive black holes (smbhs) observed already at high redshift (z ≳6 ). in the presence of a dominant, non-pbh dm component, the bounds set by cmb via an altered ionization history are modified. we revisit the cosmological accretion of a dm halo around pbhs via toy models and dedicated numerical simulations, deriving updated cmb bounds which also take into account the last planck data release. we prove that these constraints dominate over other constraints available in the literature at masses m ≳20 -50 m⊙ (depending on uncertainty in accretion physics), reaching the level fpbh<3 ×10-9 around m ∼104m⊙ . these tight bounds are nonetheless consistent with the hypothesis of a primordial origin of the smbh massive seeds. | cosmic microwave background bounds on primordial black holes including dark matter halo accretion |
we study quantum field theory on a de sitter spacetime ds$_{d+1}$ background. our main tool is the hilbert space decomposition in irreducible unitary representations of its isometry group $so(d+1,1)$. as the first application of the hilbert space formalism, we recover the källen-lehmann spectral decomposition of the scalar bulk two-point function. in the process, we exhibit a relation between poles in the corresponding spectral densities and the boundary cft data. moreover, we derive an inversion formula for the spectral density through analytical continuation from the sphere and use it to find the spectral decompisiton for a few examples. next, we study the conformal partial wave decomposition of the four-point functions of boundary operators. these correlation functions are very similar to the ones of standard conformal field theory, but have different positivity properties that follow from unitarity in de sitter. we conclude by proposing a non-perturbative conformal bootstrap approach to the study of these late-time four-point functions, and we illustrate our proposal with a concrete example for qft in ds$_2$. | towards the non-perturbative cosmological bootstrap |
the separate-universe approach gives an intuitive way to understand the evolution of cosmological perturbations in the long-wavelength limit. it uses solutions of the spatially-homogeneous equations of motion to model the evolution of the inhomogeneous universe on large scales. we show that the separate-universe approach fails on a finite range of super-hubble scales at a sudden transition from slow roll to ultra-slow roll during inflation in the very early universe. such transitions are a feature of inflation models giving a large enhancement in the primordial power spectrum on small scales, necessary to produce primordial black holes after inflation. we show that the separate-universe approach still works in a piece-wise fashion, before and after the transition, but spatial gradients on finite scales require a discontinuity in the homogeneous solution at the transition. we discuss the implications for the $\delta n$ formalism and stochastic inflation, which employ the separate-universe approximation. | the separate-universe approach and sudden transitions during inflation |
we study experimental and cosmological constraints on the extension of the standard model by three right handed neutrinos with masses between those of the pion and w boson. we combine for the first time direct, indirect and cosmological constraints in this mass range. this includes experimental constraints from neutrino oscillation data, neutrinoless double β decay, electroweak precision data, lepton universality, searches for rare lepton decays, tests of ckm unitarity and past direct searches at colliders or fixed target experiments. on the cosmological side, big bang nucleosynthesis has the most pronounced impact. our results can be used to evaluate the discovery potential of searches for heavy neutrinos at lhcb, belle ii, ship, atlas, cms or a future lepton collider. | combining experimental and cosmological constraints on heavy neutrinos |
we present the public data release of the abacussummit cosmological n-body simulation suite, produced with the abacus n-body code on the summit supercomputer of the oak ridge leadership computing facility. abacus achieves $\mathcal {o}(10^{-5})$ median fractional force error at superlative speeds, calculating 70m particle updates per second per node at early times, and 45m particle updates per second per node at late times. the simulation suite totals roughly 60 trillion particles, the core of which is a set of 139 simulations with particle mass $2\times 10^{9}\, h^{-1}\, \mathrm{m}_\odot$ in box size $2\, h^{-1}\, \mathrm{gpc}$. the suite spans 97 cosmological models, including planck 2018, previous flagship simulation cosmologies, and a linear derivative and cosmic emulator grid. a subsuite of 1883 boxes of size $500\, h^{-1}\, \mathrm{mpc}$ is available for covariance estimation. abacussummit data products span 33 epochs from z = 8 to 0.1 and include light cones, full particle snapshots, halo catalogues, and particle subsets sampled consistently across redshift. abacussummit is the largest high-accuracy cosmological n-body data set produced to date. | abacussummit: a massive set of high-accuracy, high-resolution n-body simulations |
theories of modified gravity, where light scalars with non-trivial self-interactions and non-minimal couplings to matter—chameleon and symmetron theories—dynamically suppress deviations from general relativity in the solar system. on other scales, the environmental nature of the screening means that such scalars may be relevant. the highly-nonlinear nature of screening mechanisms means that they evade classical fifth-force searches, and there has been an intense effort towards designing new and novel tests to probe them, both in the laboratory and using astrophysical objects, and by reinterpreting existing datasets. the results of these searches are often presented using different parametrizations, which can make it difficult to compare constraints coming from different probes. the purpose of this review is to summarize the present state-of-the-art searches for screened scalars coupled to matter, and to translate the current bounds into a single parametrization to survey the state of the models. presently, commonly studied chameleon models are well-constrained but less commonly studied models have large regions of parameter space that are still viable. symmetron models are constrained well by astrophysical and laboratory tests, but there is a desert separating the two scales where the model is unconstrained. the coupling of chameleons to photons is tightly constrained but the symmetron coupling has yet to be explored. we also summarize the current bounds on f( r) models that exhibit the chameleon mechanism (hu and sawicki models). the simplest of these are well constrained by astrophysical probes, but there are currently few reported bounds for theories with higher powers of r. the review ends by discussing the future prospects for constraining screened modified gravity models further using upcoming and planned experiments. | tests of chameleon gravity |
primordial black holes could have been formed in the early universe from nonlinear cosmological perturbations reentering the cosmological horizon when the universe was still radiation dominated. starting from the shape of the power spectrum on superhorizon scales, we provide a simple prescription, based on the results of numerical simulations, to compute the threshold δc for primordial black hole formation. our procedure takes into account both the nonlinearities between the gaussian curvature perturbation and the density contrast and, for the first time in the literature, the nonlinear effects arising at horizon crossing, which increase the value of the threshold by about a factor two with respect to the one computed on superhorizon scales. | threshold for primordial black holes. ii. a simple analytic prescription |
we have constructed all-sky compton parameters maps, y-maps, of the thermal sunyaev-zeldovich (tsz) effect by applying specifically tailored component separation algorithms to the 30 to 857 ghz frequency channel maps from the planck satellite. these reconstructed y-maps are delivered as part of the planck 2015 release. the y-maps are characterized in terms of noise properties and residual foreground contamination, mainly thermal dust emission at large angular scales, and cosmic infrared background and extragalactic point sources at small angular scales. specific masks are defined to minimize foreground residuals and systematics. using these masks, we compute the y-map angular power spectrum and higher order statistics. from these we conclude that the y-map is dominated by tsz signal in the multipole range, 20 <ℓ< 600. we compare the measured tsz power spectrum and higher order statistics to various physically motivated models and discuss the implications of our results in terms of cluster physics and cosmology. | planck 2015 results. xxii. a map of the thermal sunyaev-zeldovich effect |
a revised catalogue of galactic supernova remnants (snrs) is presented, along with some simple statistics of their properties. six new snrs have been added to the catalogue since the previous published version from 2014, and six entries have been removed, as they have been identified as h ii regions, leaving the number of entries in the catalogue at 294. some simple statistics of the remnants in the catalogue, and the selection effects that apply, are discussed, along with some recently proposed galactic snr candidates. | a revised catalogue of 294 galactic supernova remnants |
we study new consistent scalar-tensor theories of gravity recently introduced by langlois and noui with potentially interesting cosmological applications. we derive the conditions for the existence of a primary constraint that prevents the propagation of an additional dangerous mode associated with higher order equations of motion. we then classify the most general, consistent scalar-tensor theories that are at most quadratic in the second derivatives of the scalar field. in addition, we investigate the possible connection between these theories and (beyond) horndeski through conformal and disformal transformations. finally, we point out that these theories can be associated with new operators in the effective field theory of dark energy, which might open up new possibilities to test dark energy models in future surveys. | extended scalar-tensor theories of gravity |
we identify a scalar-tensor model embedded in the horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. the model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the new field that is equal to the speed of light. while degenerate in scalar fluctuations, self-acceleration of the model implies a present cosmological tensor mode propagation at lesssim95 % of the speed of light with a damping of the wave amplitude that is gtrsim5 % less efficient than in general relativity. we show that these discrepancies are endemic to self-accelerated horndeski theories with degenerate large-scale structure and are tested with measurements of gravitational waves emitted by events at cosmological distances. hence, gravitational-wave cosmology breaks the dark degeneracy in observations of the large-scale structure between two fundamentally different explanations of cosmic acceleration—a cosmological constant and a scalar-tensor modification of gravity. the gravitational wave event gw150914 recently detected with the aligo instruments and its potential association with a weak short gamma-ray burst observed with the fermi gbm experiment may have provided this crucial measurement. | breaking a dark degeneracy with gravitational waves |
ultra-low mass primordial black holes (pbh), which may briefly dominate the energy density of the universe but completely evaporate before the big bang nucleosynthesis (bbn), can lead to interesting observable signatures. in our previous work, we studied the generation of a doubly peaked spectrum of induced stochastic gravitational wave background (isgwb) for such a scenario and explored the possibility of probing a class of baryogenesis models wherein the emission of massive unstable particles from the pbh evaporation and their subsequent decay contributes to the matter-antimatter asymmetry. in this work, we extend the scope of our earlier work by including spinning pbhs and consider the emission of light relativistic dark sector particles, which contribute to the dark radiation (dr) and massive stable dark sector particles, thereby accounting for the dark matter (dm) component of the universe. the isgwb can probe the non-thermal production of these heavy dm particles, which cannot be accessible in laboratory searches. for the case of dr, we find a novel complementarity between the measurements of ∆neff from these emitted particles and the isgwb from pbh domination. our results indicate that the isgwb has a weak dependence on the initial pbh spin. however, for gravitons as the dr particles, the initial pbh spin plays a significant role, and only above a critical value of the initial spin parameter a*, which depends only on initial pbh mass, the graviton emission can be probed in the cmb-hd experiment. upcoming cmb experiments such as cmb-hd and cmb-bharat, together with future gw detectors like lisa and et, open up an exciting possibility of constraining the pbhs parameter space providing deeper insights into the expansion history of the universe between the end of inflation and bbn. | distinct signatures of spinning pbh domination and evaporation: doubly peaked gravitational waves, dark relics and cmb complementarity |
we study gravitational wave (gw) production in strongly supercooled cosmological phase transitions, taking particular care of models featuring a complex scalar field with a u(1) symmetric potential. we perform lattice simulations of two-bubble collisions to properly model the scalar field gradients, and compute the gw spectrum sourced by them using the thin-wall approximation in many-bubble simulations. we find that in the u(1) symmetric case the low-frequency spectrum is ∝ω whereas for a real scalar field it is ∝ω3 . in both cases the spectrum decays as ω-2 at high frequencies. | gravitational wave spectra from strongly supercooled phase transitions |
in this paper, we provide updated constraints on the bolometric quasar luminosity function (qlf) from z = 0 to z = 7. the constraints are based on an observational compilation that includes observations in the rest-frame ir, b band, uv, soft, and hard x-ray in past decades. our method follows hopkins et al. with an updated quasar sed model and bolometric and extinction corrections. the new best-fitting bolometric quasar luminosity function behaves qualitatively different from the old hopkins model at high redshift. compared with the old model, the number density normalization decreases towards higher redshift and the bright-end slope is steeper at z ≳ 2. due to the paucity of measurements at the faint end, the faint end slope at z ≳ 5 is quite uncertain. we present two models, one featuring a progressively steeper faint-end slope at higher redshift and the other featuring a shallow faint-end slope at z ≳ 5. further multiband observations of the faint-end qlf are needed to distinguish between these models. the evolutionary pattern of the bolometric qlf can be interpreted as an early phase likely dominated by the hierarchical assembly of structures and a late phase likely dominated by the quenching of galaxies. we explore the implications of this model on the ionizing photon production by quasars, the cxb spectrum, the smbh mass density, and mass functions. the predicted hydrogen photoionization rate contributed by quasars is subdominant during the epoch of reionization and only becomes important at z ≲ 3. the predicted cxb spectrum, cosmic smbh mass density, and smbh mass function are generally consistent with existing observations. | the bolometric quasar luminosity function at z = 0-7 |
the hubble tension, if not caused by any systematics, could be relieved or even resolved from modifying either the early-time or late-time universe. the early-time modifications are usually in tension with either galaxy clustering or galaxy lensing constraints. the late-time modifications are also in conflict with the constraint from the inverse distance ladder, which, however, is weakened by the dependence on a sound-horizon prior and some particular approximation for the late-time expansion history. to achieve a more general no-go argument for the late-time scenarios, we propose to use a global parametrization based on the cosmic age to consistently use the cosmic chronometers data beyond the taylor expansion domain and without the input of a sound-horizon prior. both the early-time and late-time scenarios are therefore largely ruled out, indicating the possible ways out of the hubble tension from either exotic modifications of our concordance universe or some unaccounted for systematics. | no-go guide for the hubble tension: late-time solutions |
we investigate the potential for the lisa space-based interferometer to detect the stochastic gravitational wave background produced from different mechanisms during inflation. focusing on well-motivated scenarios, we study the resulting contributions from particle production during inflation, inflationary spectator fields with varying speed of sound, effective field theories of inflation with specific patterns of symmetry breaking and models leading to the formation of primordial black holes. the projected sensitivities of lisa are used in a model-independent way for various detector designs and configurations. we demonstrate that lisa is able to probe these well-motivated inflationary scenarios beyond the irreducible vacuum tensor modes expected from any inflationary background. | science with the space-based interferometer lisa. iv: probing inflation with gravitational waves |
neutrinos, being the only fermions in the standard model of particle physics that do not possess electromagnetic or color charges, have the unique opportunity to communicate with fermions outside the standard model through mass mixing. such standard model-singlet fermions are generally referred to as "sterile neutrinos". in this review article, we discuss the theoretical and experimental motivation for sterile neutrinos, as well as their phenomenological consequences. with the benefit of hindsight in 2020, we point out potentially viable and interesting ideas. we focus in particular on sterile neutrinos that are light enough to participate in neutrino oscillations, but we also comment on the benefits of introducing heavier sterile states. we discuss the phenomenology of ev-scale sterile neutrinos in terrestrial experiments and in cosmology, we survey the global data, and we highlight various intriguing anomalies. we also expose the severe tension that exists between different data sets and prevents a consistent interpretation of the global data in at least the simplest sterile neutrino models. we discuss non-minimal scenarios that may alleviate some of this tension. we briefly review the status of kev-scale sterile neutrinos as dark matter and the possibility of explaining the matter-antimatter asymmetry of the universe through leptogenesis driven by yet heavier sterile neutrinos. | sterile neutrinos |
new early dark energy (nede) is a component of vacuum energy at the electron volt scale, which decays in a first-order phase transition shortly before recombination [f. niedermann and m. s. sloth, new early dark energy]. the nede component has the potential to resolve the tension between recent local measurements of the expansion rate of the universe using supernovae (sn) data and the expansion rate inferred from the early universe through measurements of the cosmic microwave background (cmb) when assuming λ cdm . we discuss in depth the two-scalar field model of the nede phase transition including the process of bubble percolation, collision, and coalescence. we also estimate the gravitational wave signal produced during the collision phase and argue that it can be searched for using pulsar timing arrays. in a second step, we construct an effective cosmological model, which describes the phase transition as an instantaneous process, and derive the covariant equations that match perturbations across the transition surface. fitting the cosmological model to cmb, baryonic acoustic oscillations, and sn data, we report h0=69.6-1.3+1.0 km s-1 mpc-1 (68% c.l.) without the local measurement of the hubble parameter, bringing the tension down to 2.5 σ . including the local input, we find h0=71.4 ±1.0 km s-1 mpc-1 (68% c.l.) and strong evidence for a nonvanishing nede component with a ≃4 σ significance. | resolving the hubble tension with new early dark energy |
we review the formation and evaporation of primordial black holes (pbhs) and their possible contribution to dark matter. various constraints suggest they could only provide most of it in the mass windows $10^{17}$ - $10^{23}\,$g or $10$ - $10^{2}\,m_{\odot}$, with the last possibility perhaps being suggested by the ligo/virgo observations. however, pbhs could have important consequences even if they have a low cosmological density. sufficiently large ones might generate cosmic structures and provide seeds for the supermassive black holes in galactic nuclei. planck-mass relics of pbh evaporations or stupendously large black holes bigger than $10^{12}\,m_{\odot}$ could also be an interesting dark component. | primordial black holes as dark matter candidates |
we revisit the possibility that the stochastic common-spectrum process recently detected by the nanograv pulsar timing array experiment could be due to primordial gravitational waves (gws). a naïve extrapolation down to interferometer scales of the blue gw spectrum required to explain nanograv consistently with cosmic microwave background (cmb) observations would strongly violate upper limits on the stochastic gw background (sgwb) amplitude from laser interferometer gravitational wave observatory/virgo. in combination with the fact that there are over 19 decades in frequency between cmb and interferometer scales, this motivates us to move beyond the commonly adopted approximation of a pure power-law gw spectrum. we consider a broken power-law parametrization for the sgwb spectrum, which turns from blue to red above the break frequency: while phenomenological, this choice maps to various well-motivated early-universe models, including scenarios featuring noninstantaneous reheating or a nonstandard background expansion following reheating. after a detailed discussion of the contribution of the resulting sgwb to the early-universe radiation energy density, we constrain the broken power-law model against a wide variety of multifrequency cosmological and gw observations. we find that this phenomenological model is able to explain the nanograv signal while remaining in agreement with upper limits on the tensor-to-scalar ratio on cmb scales, big bang nucleosynthesis constraints on the early-universe radiation energy density, and upper limits on the sgwb amplitude on interferometer scales. we briefly discuss the very bright prospects for testing this model with next-generation probes across the gw frequency landscape, which motivate further exploring connections to specific well-motivated early-universe models. | primordial gravitational waves from nanograv: a broken power-law approach |
in the current 3nu paradigm, flavor oscillations probe 3 mixing angles (theta_12, theta_23, theta_13), one cp phase delta, and two squared mass differences delta m^2>0 and delta m^2, where sign(delta m^2)=+ (-) for normal (inverted) ordering. absolute nu masses can be probed by the effective m_beta in beta decay, by the total mass sigma in cosmology and, if neutrinos are majorana, by another effective m_{beta beta} in 0nu2beta decay. within an updated global analysis of (non)oscillation data, we constrain these 3nu parameters, both separately and in selected pairs, and highlight the concordance or discordance among different constraints. five oscillation parameters (delta m^2, delta m^2, theta_12, theta_23, theta_13) are consistently measured, with an overall accuracy ranging from ~1% for delta m^2 to ~6% for sin^2(theta_23) (due to its octant ambiguity). we find overall hints for normal ordering (at 2.5 sigma), as well as for theta_23<pi/4 and for sin(delta)<0 (both at 90% c.l.), and discuss some tensions among datasets. concerning nonoscillation data, we include the recent katrin constraints on m_beta, and we combine the latest 76-ge, 130-te and 136-xe bounds on m_{beta beta}, accounting for nme covariances. we also discuss some variants related to cmb anisotropy and lensing data, which may affect cosmological constraints on sigma and hints on sign(delta m^2). the default option, including all planck results, irrespective of the lensing anomaly, sets upper bounds on sigma at the level of ~10^-1 ev, and further favors normal ordering up to ~3 sigma. an alternative option, that includes recent act results + other independent results (from wmap and selected planck data) globally consistent with standard lensing, is insensitive to the ordering but prefers sigma ~(few) x 10^-1 ev, with different implications for m_beta and m_{beta beta} searches. (abridged) | the unfinished fabric of the three neutrino paradigm |
a tantalizing hint of isotropic cosmic birefringence has been found in the e b cross-power spectrum of the cosmic microwave background (cmb) polarization data with a statistical significance of 3 σ . a pseudoscalar field coupled to the cmb photons via the chern-simons term can explain this observation. the same field may also be responsible for early dark energy (ede), which alleviates the so-called hubble tension. since the ede field evolves significantly during the recombination epoch, the conventional formula that relates e b to the difference between the e - and b -mode autopower spectra is no longer valid. solving the boltzmann equation for polarized photons and the dynamics of the ede field consistently, we find that currently favored parameter space of the ede model yields a variety of shapes of the e b spectrum, which can be tested by cmb experiments. | isotropic cosmic birefringence from early dark energy |
we present the muse hubble ultra deep survey, a mosaic of nine muse fields covering 90% of the entire hudf region with a 10-h deep exposure time, plus a deeper 31-h exposure in a single 1.15 arcmin2 field. the improved observing strategy and advanced data reduction results in datacubes with sub-arcsecond spatial resolution (0.̋65 at 7000 å) and accurate astrometry (0.̋07 rms). we compare the broadband photometric properties of the datacubes to hst photometry, finding a good agreement in zeropoint up to mab = 28 but with an increasing scatter for faint objects. we have investigated the noise properties and developed an empirical way to account for the impact of the correlation introduced by the 3d drizzle interpolation. the achieved 3σ emission line detection limit for a point source is 1.5 and 3.1 × 10-19 erg s-1 cm-2 for the single ultra-deep datacube and the mosaic, respectively. we extracted 6288 sources using an optimal extraction scheme that takes the published hst source locations as prior. in parallel, we performed a blind search of emission line galaxies using an original method based on advanced test statistics and filter matching. the blind search results in 1251 emission line galaxy candidates in the mosaic and 306 in the ultradeep datacube, including 72 sources without hst counterparts (mab > 31). in addition 88 sources missed in the hst catalog but with clear hst counterparts were identified. this data set is the deepest spectroscopic survey ever performed. in just over 100 h of integration time, it provides nearly an order of magnitude more spectroscopic redshifts compared to the data that has been accumulated on the udf over the past decade. the depth and high quality of these datacubes enables new and detailed studies of the physical properties of the galaxy population and their environments over a large redshift range. based on observations made with eso telescopes at the la silla paranal observatory under programs 094.a-0289(b), 095.a-0010(a), 096.a-0045(a) and 096.a-0045(b). | the muse hubble ultra deep field survey. i. survey description, data reduction, and source detection |
dark matter interacting via the exchange of a light pseudoscalar can induce observable signals in indirect detection experiments and experience large self-interactions while evading the strong bounds from direct dark matter searches. the pseudoscalar mediator will however induce flavour-changing interactions in the standard model, providing a promising alternative way to test these models. we investigate in detail the constraints arising from rare meson decays and fixed target experiments for different coupling structures between the pseudoscalar and standard model fermions. the resulting bounds are highly complementary to the information inferred from the dark matter relic density and the constraints from primordial nucleosynthesis. we discuss the implications of our findings for the dark matter self-interaction cross section and the prospects of probing dark matter coupled to a light pseudoscalar with direct or indirect detection experiments. in particular, we find that a pseudoscalar mediator can only explain the galactic centre excess if its mass is above that of the b mesons, and that it is impossible to obtain a sufficiently large direct detection cross section to account for the dama modulation | erratum: erratum to: a taste of dark matter: flavour constraints on pseudoscalar mediators |
we present uv luminosity functions of dropout galaxies at z∼ 6{--}10 with the complete hubble frontier fields data. we obtain a catalog of ∼450 dropout-galaxy candidates (350, 66, and 40 at z∼ 6{--}7, 8, and 9, respectively), with uv absolute magnitudes that reach ∼ -14 mag, ∼2 mag deeper than the hubble ultra deep field detection limits. we carefully evaluate number densities of the dropout galaxies by monte carlo simulations, including all lensing effects such as magnification, distortion, and multiplication of images as well as detection completeness and contamination effects in a self-consistent manner. we find that uv luminosity functions at z∼ 6{--}8 have steep faint-end slopes, α ∼ -2, and likely steeper slopes, α ≲ -2 at z∼ 9{--}10. we also find that the evolution of uv luminosity densities shows a non-accelerated decline beyond z∼ 8 in the case of {m}trunc}=-15, but an accelerated one in the case of {m}trunc}=-17. we examine whether our results are consistent with the thomson scattering optical depth from the planck satellite and the ionized hydrogen fraction q h iiat z≲ 7 based on the standard analytic reionization model. we find that reionization scenarios exist that consistently explain all of the observational measurements with the allowed parameters of {f}esc}={0.17}-0.03+0.07 and {m}trunc}> -14.0 for {log}{ξ }ion}/[{erg}}-1 {hz}]=25.34, where {f}esc} is the escape fraction, m trunc is the faint limit of the uv luminosity function, and {ξ }ion} is the conversion factor of the uv luminosity to the ionizing photon emission rate. the length of the reionization period is estimated to be {{δ }}z={3.9}-1.6+2.0 (for 0.1< {q}{{h}{{ii}}}< 0.99), consistent with the recent estimate from planck. | full-data results of hubble frontier fields: uv luminosity functions at z ∼ 6-10 and a consistent picture of cosmic reionization |
luminous quasars at z> 5.6 can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe. thus far, these studies have been statistically limited by the number of quasars known at these redshifts. such quasars are rare, and therefore, wide-field surveys are required to identify them, and multiwavelength data are required to separate them efficiently from their main contaminants, the far more numerous cool dwarfs. in this paper, we update and extend the selection for the z∼ 6 quasars presented in bañados et al. (2014) using the pan-starrs1 (ps1) survey. we present the ps1 distant quasar sample, which currently consists of 124 quasars in the redshift range 5.6≲ z≲ 6.7 that satisfy our selection criteria. of these quasars, 77 have been discovered with ps1, and 63 of them are newly identified in this paper. we present the composite spectra of the ps1 distant quasar sample. this sample spans a factor of ∼20 in luminosity and shows a variety of emission line properties. the number of quasars at z> 5.6 presented in this work almost doubles the previously known quasars at these redshifts, marking a transition phase from studies of individual sources to statistical studies of the high-redshift quasar population, which was impossible with earlier, smaller samples. | the pan-starrs1 distant z > 5.6 quasar survey: more than 100 quasars within the first gyr of the universe |
galactic cosmic rays reach energies of at least a few petaelectronvolts (of the order of 1015 electronvolts). this implies that our galaxy contains petaelectronvolt accelerators (‘pevatrons’), but all proposed models of galactic cosmic-ray accelerators encounter difficulties at exactly these energies. dozens of galactic accelerators capable of accelerating particles to energies of tens of teraelectronvolts (of the order of 1013 electronvolts) were inferred from recent γ-ray observations. however, none of the currently known accelerators—not even the handful of shell-type supernova remnants commonly believed to supply most galactic cosmic rays—has shown the characteristic tracers of petaelectronvolt particles, namely, power-law spectra of γ-rays extending without a cut-off or a spectral break to tens of teraelectronvolts. here we report deep γ-ray observations with arcminute angular resolution of the region surrounding the galactic centre, which show the expected tracer of the presence of petaelectronvolt protons within the central 10 parsecs of the galaxy. we propose that the supermassive black hole sagittarius a* is linked to this pevatron. sagittarius a* went through active phases in the past, as demonstrated by x-ray outburstsand an outflow from the galactic centre. although its current rate of particle acceleration is not sufficient to provide a substantial contribution to galactic cosmic rays, sagittarius a* could have plausibly been more active over the last 106-107 years, and therefore should be considered as a viable alternative to supernova remnants as a source of petaelectronvolt galactic cosmic rays. | acceleration of petaelectronvolt protons in the galactic centre |
we present an analysis of type ia supernovae (sne~ia) from both the carnegie supernova project~i (csp-i) and ii (csp-ii), and extend the hubble diagram from the optical to the near-infrared wavelengths ($ubgvriyjh$). we calculate the hubble constant, $h_0$, using various distance calibrators: cepheids, tip of the red giant branch (trgb), and surface brightness fluctuations (sbf). combining all methods of calibrations, we derive $\rm h_0=71.76 \pm 0.58 \ (stat) \pm 1.19 \ (sys) \ km \ s^{-1} \ mpc^{-1}$ from $b$-band, and $\rm h_0=73.22 \pm 0.68 \ (stat) \pm 1.28 \ (sys) \ km \ s^{-1} \ mpc^{-1}$ from $h$-band. by assigning equal weight to the cepheid, trgb, and sbf calibrators, we derive the systematic errors required for consistency in the first rung of the distance ladder, resulting in a systematic error of $1.2\sim 1.3 \rm \ km \ s^{-1} \ mpc^{-1}$ in $h_0$. as a result, relative to the statistics-only uncertainty, the tension between the late-time $h_0$ we derive by combining the various distance calibrators and the early-time $h_0$ from the cosmic microwave background is reduced. the highest precision in sn~ia luminosity is found in the $y$ band ($0.12\pm0.01$ mag), as defined by the intrinsic scatter ($\sigma_{int}$). we revisit sn~ia hubble residual-host mass correlations and recover previous results that these correlations do not change significantly between the optical and the near-infrared wavelengths. finally, sne~ia that explode beyond 10 kpc from their host centers exhibit smaller dispersion in their luminosity, confirming our earlier findings. reduced effect of dust in the outskirt of hosts may be responsible for this effect. | carnegie supernova project-i and -ii: measurements of $h_0$ using cepheid, trgb, and sbf distance calibration to type ia supernovae |
motivated by the nanograv 15 year data and other recent investigations of stochastic gravitational background radiation based on pulsar timing arrays, we show how superheavy strings survive inflation but the slightly heavier monopoles do not in a non-supersymmetric hybrid inflation model based on flipped $su(5)$. with the dimensionless string tension parameter $g \mu\sim 10^{-6}$, the gravitational wave spectrum emitted by the strings, which are metastable due to breaking caused by monopole-antimonopole quantum mechanical tunneling, is compatible with the latest nanograv measurement as well as the advanced ligo-virgo third run data. the string network undergoes about 30 $e$-foldings of inflation which suppresses the spectrum in the ligo-virgo frequency range. with the symmetry breaking chain $su(5) \times u(1)_x \to su(3)_c \times su(2)_l\times u(1)_z \times u(1)_x \to su(3)_c \times su(2)_l \times u(1)_ y$, the estimated proton lifetime is of order $10^{36}-10^{37}$ yrs. | inflation, superheavy metastable strings and gravitational waves in non-supersymmetric flipped su(5) |
we report the first direct detection of the cosmological power spectrum using the intensity signal from 21-cm emission of neutral hydrogen (hi), derived from interferometric observations with the l-band receivers of the new meerkat radio telescope. intensity mapping is a promising technique to map the three-dimensional matter distribution of the universe at radio frequencies and probe the underlying cosmology. so far, detections have only been achieved through cross-correlations with galaxy surveys. here we present independent measurements of the hi power spectrum at redshifts $0.32$ and $0.44$ with high statistical significance using a foreground avoidance method (at $8.0\sigma$ and $11.5\sigma$ respectively). we constrain the rms of the fluctuations of the hi distribution to be $\sigma_{\rm hi} = (0.44\pm 0.04)\,{\rm mk}$ and $\sigma_{\rm hi} = (0.63\pm 0.03)\,{\rm mk}$ respectively at scales of 1.0 mpc. the information contained in the power spectrum measurements allows us to probe the parameters of the hi mass function and hi halo model. these results are a significant step towards precision cosmology with hi intensity mapping using the new generation of radio telescopes. | a first detection of neutral hydrogen intensity mapping on mpc scales at $z\\approx 0.32$ and $z\\approx 0.44$ |
we present quantities which characterize the sensitivity of gravitational-wave observatories to sources at cosmological distances. in particular, we introduce and generalize the horizon, range, response, and reach distances. these quantities incorporate a number of important effects, including cosmologically well-defined distances and volumes, cosmological redshift, cosmological time dilation, and rate density evolution. in addition, these quantities incorporate unique aspects of gravitational wave detectors, such as the variable sky sensitivity of the detectors and the scaling of the sensitivity with inverse distance. an online calculator (https://users.rcc.uchicago.edu/~dholz/gwc/) and python notebook (https://github.com/hsinyuc/distancetool) to determine gw distances are available. we provide answers to the question: 'how far can gravitational-wave detectors hear?' | distance measures in gravitational-wave astrophysics and cosmology |
the eighteenth data release (dr18) of the sloan digital sky survey (sdss) is the first one for sdss-v, the fifth generation of the survey. sdss-v comprises three primary scientific programs or "mappers": the milky way mapper (mwm), the black hole mapper (bhm), and the local volume mapper. this data release contains extensive targeting information for the two multiobject spectroscopy programs (mwm and bhm), including input catalogs and selection functions for their numerous scientific objectives. we describe the production of the targeting databases and their calibration and scientifically focused components. dr18 also includes ~25,000 new sdss spectra and supplemental information for x-ray sources identified by erosita in its efeds field. we present updates to some of the sdss software pipelines and preview changes anticipated for dr19. we also describe three value-added catalogs (vacs) based on sdss-iv data that have been published since dr17, and one vac based on the sdss-v data in the efeds field. | the eighteenth data release of the sloan digital sky surveys: targeting and first spectra from sdss-v |
the standard cosmological model determined from the accurate cosmic microwave background measurements made by the planck satellite implies a value of the hubble constant h0 that is 4.2 standard deviations lower than the one determined from type ia supernovae. the planck best fit model also predicts higher values of the matter density fraction ωm and clustering amplitude s8 compared to those obtained from the dark energy survey year 1 data. here we show that accounting for the enhanced recombination rate due to additional small-scale inhomogeneities in the baryon density may solve both the h0 and the s8-ωm tensions. the additional baryon inhomogeneities can be induced by primordial magnetic fields present in the plasma prior to recombination. the required field strength to solve the hubble tension is just what is needed to explain the existence of galactic, cluster, and extragalactic magnetic fields without relying on dynamo amplification. our results show clear evidence for this effect and motivate further detailed studies of primordial magnetic fields, setting several well-defined targets for future observations. | relieving the hubble tension with primordial magnetic fields |
we propose a model of inflation capable of generating a population of light black holes (about 10-16- 10-14 solar masses) that might account for a significant fraction of the dark matter in the universe. the effective potential of the model features an approximate inflection point arising from two-loop order logarithmic corrections in well-motivated and perturbative particle physics examples. this feature decelerates the inflaton before the end of inflation, enhancing the primordial spectrum of scalar fluctuations and triggering efficient black hole production with a peaked mass distribution. at larger field values, inflation occurs thanks to a generic small coupling between the inflaton and the curvature of spacetime. we compute accurately the peak mass and abundance of the primordial black holes using the press-schechter and mukhanov-sasaki formalisms, showing that the slow-roll approximation fails to reproduce the correct results by orders of magnitude. we study as well a qualitatively similar implementation of the idea, where the approximate inflection point is due to competing terms in a generic polynomial potential. in both models, requiring a significant part of the dark matter abundance to be in the form of black holes implies a small blue scalar tilt with a sizable negative running and a tensor spectrum that may be detected by the next-generation probes of the cosmic microwave background. we also comment on previous works on the topic. | primordial black hole dark matter from single field inflation |
we discuss the possibility of forming primordial black holes during a first-order phase transition in the early universe. as is well known, such a phase transition proceeds through the formation of true-vacuum bubbles in a universe that is still in a false vacuum. when there is a particle species whose mass increases significantly during the phase transition, transmission of the corresponding particles through the advancing bubble walls is suppressed. consequently, an overdensity can build up in front of the walls and become sufficiently large to trigger primordial black hole formation. we track this process quantitatively by solving a boltzmann equation, and we determine the resulting black hole density and mass distribution as a function of model parameters. | primordial black holes from first-order cosmological phase transitions |
we present the first joint analysis of gamma-ray data from the magic cherenkov telescopes and the fermi large area telescope (lat) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. we combine 158 hours of segue 1 observations with magic with 6-year observations of 15 dwarf satellite galaxies by the fermi-lat. we obtain limits on the annihilation cross-section for dark matter particle masses between 10 gev and 100 tev-the widest mass range ever explored by a single gamma-ray analysis. these limits improve on previously published fermi-lat and magic results by up to a factor of two at certain masses. our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors. | limits to dark matter annihilation cross-section from a combined analysis of magic and fermi-lat observations of dwarf satellite galaxies |
it is twenty years since the seminal works by magorrian and co-authors and by silk and rees, which, along with other related work, ignited an explosion of publications connecting active galactic nucleus (agn)-driven outflows to galaxy evolution. with a surge in observations of agn outflows, studies are attempting to test agn feedback models directly using the outflow properties. with a focus on outflows traced by optical and co emission lines, we discuss significant challenges that greatly complicate this task, from both an observational and theoretical perspective. we highlight the observational uncertainties involved and the assumptions required when deriving kinetic coupling efficiencies (that is, outflow kinetic power as a fraction of agn luminosity) from typical observations. based on recent models we demonstrate that extreme caution should be taken when comparing observationally derived kinetic coupling efficiencies to coupling efficiencies from fiducial feedback models. | agn outflows and feedback twenty years on |
we study the gravothermal evolution of dark matter halos in the presence of dissipative dark matter self-interactions. dissipative interactions are present in many particle-physics realizations of the dark-sector paradigm and can significantly accelerate the gravothermal collapse of halos compared to purely elastic dark matter self-interactions. this is the case even when the dissipative interaction timescale is longer than the free-fall time of the halo. using a semianalytical fluid model calibrated with isolated and cosmological n -body simulations, we calculate the evolution of the halo properties—including its density profile and velocity dispersion profile—as well as the core-collapse time as a function of the particle model parameters that describe the interactions. a key property is that the inner density profile at late times becomes cuspy again. using 18 dwarf galaxies that exhibit a corelike dark matter density profile, we derive constraints on the strength of the dissipative interactions and the energy loss per collision. | constraining dissipative dark matter self-interactions |
understanding the nature of quantum chromodynamics (qcd) matter is important but challenging due to the presence of non-perturbative dynamics under extreme conditions. we construct a holographic model describing the gluon sector of qcd at finite temperatures in the non-perturbative regime. the equation of state as a function of temperature is in good accordance with the lattice qcd data. moreover, the polyakov loop and the gluon condensation, which are proper order parameters to capture the deconfinement phase transition, also agree quantitatively well with the lattice qcd data. we obtain a strong first-order confinement/deconfinement phase transition at $t_c=276.5\,\text{mev}$ that is consistent with the lattice qcd prediction. based on our model for a pure gluon hidden sector, we compute the stochastic gravitational waves and primordial black hole (pbh) productions from this confinement/deconfinement phase transition in the early universe. the resulting stochastic gravitational-wave backgrounds are found to be within detectability in the international pulsar timing array and square kilometre array in the near future when the associated productions of pbhs saturate the current observational bounds on the pbh abundances from the ligo-virgo-collaboration o3 data. | gravitational waves and primordial black hole productions from gluodynamics by holography |
cosmological simulations are an important theoretical pillar for understanding non-linear structure formation in our universe and for relating it to observations on large scales. in several papers, we introduce our millenniumtng (mtng) project that provides a comprehensive set of high-resolution, large-volume simulations of cosmic structure formation aiming to better understand physical processes on large scales and to help interpret upcoming large-scale galaxy surveys. we here focus on the full physics box mtng740 that computes a volume of $740\, \mathrm{mpc}^3$ with a baryonic mass resolution of $3.1\times ~10^7\, \mathrm{m_\odot }$ using arepo with 80.6 billion cells and the illustristng galaxy formation model. we verify that the galaxy properties produced by mtng740 are consistent with the tng simulations, including more recent observations. we focus on galaxy clusters and analyse cluster scaling relations and radial profiles. we show that both are broadly consistent with various observational constraints. we demonstrate that the sz-signal on a deep light-cone is consistent with planck limits. finally, we compare mtng740 clusters with galaxy clusters found in planck and the sdss-8 redmapper richness catalogue in observational space, finding very good agreement as well. however, simultaneously matching cluster masses, richness, and compton-y requires us to assume that the sz mass estimates for planck clusters are underestimated by 0.2 dex on average. due to its unprecedented volume for a high-resolution hydrodynamical calculation, the mtng740 simulation offers rich possibilities to study baryons in galaxies, galaxy clusters, and in large-scale structure, and in particular their impact on upcoming large cosmological surveys. | the millenniumtng project: the hydrodynamical full physics simulation and a first look at its galaxy clusters |
we show that a two-excitation process in superfluid helium, combined with sensitivity to mev energy depositions, can probe dark matter down to the ∼kev warm dark matter mass limit. this mass reach is 3 orders of magnitude below what can be probed with ordinary nuclear recoils in helium at the same energy resolution. for dark matter lighter than ∼100 kev , the kinematics of the process requires the two athermal excitations to have nearly equal and opposite momentum, potentially providing a built-in coincidence mechanism for controlling backgrounds. | detectability of light dark matter with superfluid helium |
the origins of lyman continuum (lyc) photons responsible for the reionization of the universe are as of yet unknown and highly contested. detecting lyc photons from the epoch of reionization is not possible due to absorption by the intergalactic medium, which has prompted the development of several indirect diagnostics to infer the rate at which galaxies contribute lyc photons to reionize the universe by studying lower-redshift analogs. we present the low-redshift lyman continuum survey (lzlcs) comprising measurements made with the hubble space telescope cosmic origins spectrograph for a z = 0.2-0.4 sample of 66 galaxies. after careful processing of the far-uv spectra, we obtain a total of 35 lyman continuum emitters (lces) detected with 97.725% confidence, nearly tripling the number of known local lces. we estimate escape fractions from the detected lyc flux and upper limits on the undetected lyc flux, finding a range of lyc escape fractions up to 50%. of the 35 lzlcs lces, 12 have lyc escape fractions greater than 5%, more than doubling the number of known local lces with cosmologically relevant lyc escape. | the low-redshift lyman continuum survey. i. new, diverse local lyman continuum emitters |
the black hole binary (bhb) coalescence rates inferred from the advanced ligo detection of gw150914 imply an unexpectedly loud gravitational-wave (gw) sky at millihertz frequencies accessible to the evolved laser interferometer space antenna (elisa), with several outstanding consequences. first, up to thousands of bhbs will be individually resolvable by elisa; second, millions of nonresolvable bhbs will build a confusion noise detectable with a signal-to-noise ratio of a few to hundreds; third—and perhaps most importantly—up to hundreds of bhbs individually resolvable by elisa will coalesce in the advanced ligo band within 10 y. elisa observations will tell advanced ligo and all electromagnetic probes weeks in advance when and where these bhb coalescences will occur, with uncertainties of <10 s and <1 deg2 . this will allow the prepointing of telescopes to realize coincident gw and multiwavelength electromagnetic observations of bhb mergers. time coincidence is critical, because a prompt emission associated to a bhb merger will likely have a duration comparable to the dynamical time scale of the systems and is possible only with low-frequency gw alerts. | prospects for multiband gravitational-wave astronomy after gw150914 |
identifying the astrophysical sources responsible for the high-energy cosmic neutrinos has been a longstanding challenge. in a previous work, we report evidence for a spatial correlation between blazars from the 5th roma-bzcat catalog and neutrino data of the highest detectable energies, i.e. >0.1 pev, collected by the icecube observatory in the southern celestial hemisphere. the statistical significance is found at the level of 2 x 10^{-6} post-trial. in this work we test whether a similar correlation exists in the northern hemisphere, were icecube is mostly sensitive to <0.1 pev energies. we find a consistent correlation between blazars and northern neutrino data at the pre-trial p-value of 5.12 x 10^{-4}, and a post-trial chance probability of 6.79 x 10^{-3}. combining the post-trial probabilities observed for the southern and northern experiments yields a global post-trial chance probability of 2.59 x 10^{-7} for the genuineness of such correlation. this implies that the spatial correlation is highly unlikely to arise by chance. our studies push forward an all-sky subset of 52 objects as highly likely pevatron extragalactic accelerators. | extragalactic neutrino factories |
we present a sample-variance-limited measurement of the temperature power spectrum (t t ) of the cosmic microwave background using observations of a ∼1500 deg2 field made by the spt-3g in 2018. we report multifrequency power spectrum measurements at 95, 150, and 220 ghz covering the angular multipole range 750 ≤ℓ<3000 . we combine this t t measurement with the published polarization power spectrum measurements from the 2018 observing season and update their associated covariance matrix to complete the spt-3g 2018 t t /t e /e e dataset. this is the first analysis to present cosmological constraints from spt t t , t e , and e e power spectrum measurements jointly. we blind the cosmological results and subject the dataset to a series of consistency tests at the power spectrum and parameter level. we find excellent agreement between frequencies and spectrum types and our results are robust to the modeling of astrophysical foregrounds. we report results for λ cdm and a series of extensions, drawing on the following parameters: the amplitude of the gravitational lensing effect on primary power spectra al, the effective number of neutrino species neff, the primordial helium abundance yp, and the baryon clumping factor due to primordial magnetic fields b . we find that the spt-3g 2018 t t /t e /e e data are well fit by λ cdm with a probability to exceed of 15%. for λ cdm , we constrain the expansion rate today to h0=68.3 ±1.5 km s-1 mpc-1 and the combined structure growth parameter to s8=0.797 ±0.042 . the spt-based results are effectively independent of planck, and the cosmological parameter constraints from either dataset are within <1 σ of each other. the addition of temperature data to the spt-3g t e /e e power spectra improves constraints by 8-27% for each of the λ cdm cosmological parameters. when additionally fitting al, neff, or neff+yp, the posteriors of these parameters tighten by 5-24%. in the case of primordial magnetic fields, complete t t /t e /e e power spectrum measurements are necessary to break the degeneracy between b and ns, the spectral index of primordial density perturbations. we report a 95% confidence upper limit from spt-3g data of b <1.0 . the cosmological constraints in this work are the tightest from spt primary power spectrum measurements to date and the analysis forms a new framework for future spt analyses. | measurement of the cmb temperature power spectrum and constraints on cosmology from the spt-3g 2018 t t , t e , and e e dataset |
the axion emerges in extensions of the standard model that explain the absence of cp violation in the strong interactions. simultaneously, it can provide naturally the cold dark matter in our universe. several searches for axions and axion-like particles (alps) have constrained the corresponding parameter space over the last decades but no unambiguous hints of their existence have been found. the axion mass range below 1 mev remains highly attractive and a well motivated region for dark matter axions. in this white paper we present a description of a new experiment based on the concept of a dielectric haloscope for the direct search of dark matter axions in the mass range of 40 to 400 μ ev. this magnetized disk and mirror axion experiment (madmax) will consist of several parallel dielectric disks, which are placed in a strong magnetic field and with adjustable separations. this setting is expected to allow for an observable emission of axion induced electromagnetic waves at a frequency between 10 to 100 ghz corresponding to the axion mass. | a new experimental approach to probe qcd axion dark matter in the mass range above { 40} {μ }{ev} |
in this letter, combining peak theory and the numerical analysis of gravitational collapse in the radiation dominated era, we show that the abundance of primordial blacks holes, generated by an enhancement in the inflationary power spectrum, is extremely dependent on the shape of the peak. given the amplitude of the power spectrum, we show that the density of primordial black holes generated from a narrow peak is exponentially smaller than in the case of a broad peak. specifically, for a top-hat profile of the power spectrum in fourier space, we find that to have primordial black holes comprising all of the dark matter, one would only need a power spectrum amplitude an order of magnitude smaller than suggested previously, whereas in the case of a narrow peak, one would instead need a much larger power spectrum amplitude, which in many cases would invalidate the perturbative analysis of cosmological perturbations. finally, we show that, although critical collapse gives a broad mass spectrum, the density of primordial black holes formed is dominated by masses roughly equal to the cosmological horizon mass measured at horizon crossing. | abundance of primordial black holes depends on the shape of the inflationary power spectrum |
we describe blackhawk, a public c program for calculating the hawking evaporation spectra of any black hole distribution. this program enables the users to compute the primary and secondary spectra of stable or long-lived particles generated by hawking radiation of the distribution of black holes, and to study their evolution in time. the physics of hawking radiation is presented, and the capabilities, features and usage of blackhawk are described here under the form of a manual. the blackhawk code can be downloaded from <externalref> <refsource>https://blackhawk.hepforge.org</refsource> <reftarget address="https://blackhawk.hepforge.org" targettype="url"/> </externalref>. | blackhawk: a public code for calculating the hawking evaporation spectra of any black hole distribution |
we study the standard model (sm) in weyl conformal geometry. this embedding is truly minimal with no new fields beyond the sm spectrum and weyl geometry. the action inherits a gauged scale symmetry d(1) (known as weyl gauge symmetry) from the underlying geometry. the associated weyl quadratic gravity undergoes spontaneous breaking of d(1) by a geometric stueckelberg mechanism in which the weyl gauge field (ωμ) acquires mass by "absorbing" the spin-zero mode of the r~ 2 term in the action. this mode also generates the planck scale and the cosmological constant. the einstein-proca action emerges in the broken phase. in the presence of the sm, this mechanism receives corrections (from the higgs) and it can induce electroweak (ew) symmetry breaking. the ew scale is proportional to the vev of the stueckelberg field. the higgs field (σ ) has direct couplings to the weyl gauge field (σ2ωμωμ ). the sm fermions only acquire such couplings for non-vanishing kinetic mixing of the gauge fields of d (1 ) ×u (1) y . if this mixing is present, part of the mass of z boson is not due to the usual higgs mechanism, but to its mixing with massive ωμ. precision measurements of z mass then set lower bounds on the mass of ωμ which can be light (few tev). in the early universe the higgs field can have a geometric origin, by weyl vector fusion, and the higgs potential can drive inflation. the dependence of the tensor-to-scalar ratio r on the spectral index ns is similar to that in starobinsky inflation but mildly shifted to lower r by the higgs non-minimal coupling to weyl geometry. | standard model in weyl conformal geometry |
we study how the evaporation of primordial black holes (pbhs) can affect the production of dark matter (dm) particles through thermal processes. we consider fermionic dm interacting with standard model particles via a spin-1 mediator in the context of a freeze-out or freeze-in mechanism. we show that when pbhs evaporate after dominating the universe's energy density, pbhs act as a source of dm and continuously inject entropy into the visible sector that can affect the thermal production in three qualitatively different ways. we compute the annihilation cross sections which account for the interactions between and within the pbh produced and thermally produced dm populations, and establish a set of boltzmann equations which we solve to obtain the correct relic abundance in those different regimes and confront the results with a set of different cosmological constraints. we provide analytic formulas to calculate the relic abundance for the freeze-out and freeze-in mechanism in a pbh dominated early universe. we identify regions of the parameter space where the pbhs dilute the relic density and thermalization occurs. furthermore, we have made our code that numerically solves the boltzmann equations publicly available. | primordial black hole evaporation and dark matter production. ii. interplay with the freeze-in or freeze-out mechanism |
the five-hundred-meter aperture spherical radio telescope (fast) has passed national acceptance and finished one pilot cycle of 'shared-risk' observations. it will start formal operation soon. in this context, this paper describes testing results of key fundamental parameters for fast, aiming to provide basic support for observation and data reduction of fast for scientific researchers. the 19-beam receiver covering 1.05-1.45 ghz was utilized for most of these observations. the fluctuation in electronic gain of the system is better than 1% over 3.5 hours, enabling enough stability for observations. pointing accuracy, aperture efficiency and system temperature are three key parameters for fast. the measured standard deviation of pointing accuracy is 7.9″, which satisfies the initial design of fast. when zenith angle is less than 26.4°, the aperture efficiency and system temperature around 1.4 ghz are ∼0.63 and less than 24 k for central beam, respectively. the sensitivity and stability of the 19-beam backend are confirmed to satisfy expectation by spectral hi observations toward ngc 672 and polarization observations toward 3c 286. the performance allows fast to take sensitive observations for various scientific goals, from studies of pulsars to galaxy evolution. | the fundamental performance of fast with 19-beam receiver at l band |
we investigate the anisotropic clustering of the baryon oscillation spectroscopic survey (boss) data release 12 sample, which consists of 1198 006 galaxies in the redshift range 0.2 < z < 0.75 and a sky coverage of 10 252 deg2. we analyse this data set in fourier space, using the power-spectrum multipoles to measure redshift-space distortions simultaneously with the alcock-paczynski effect and the baryon acoustic oscillation scale. we include the power-spectrum monopole, quadrupole and hexadecapole in our analysis and compare our measurements with a perturbation-theory-based model, while properly accounting for the survey window function. to evaluate the reliability of our analysis pipeline, we participate in a mock challenge, which results in systematic uncertainties significantly smaller than the statistical uncertainties. while the high-redshift constraint on fσ8 at zeff = 0.61 indicates a small (∼1.4σ) deviation from the prediction of the planck λcdm (λ cold dark matter) model, the low-redshift constraint is in good agreement with planck λcdm. this paper is part of a set that analyses the final galaxy clustering data set from boss. the measurements and likelihoods presented here are combined with others in alam et al. to produce the final cosmological constraints from boss. | the clustering of galaxies in the completed sdss-iii baryon oscillation spectroscopic survey: anisotropic galaxy clustering in fourier space |
the f(q) theories of modified gravity arise from the consideration of non-metricity as the basic geometric quantity, and have been proven to be very efficient in describing the late-time universe. we use the big bang nucleosynthesis (bbn) formalism and observations in order to extract constraints on various classes of f(q) models. in particular, we calculate the deviations that f(q) terms bring on the freeze-out temperature tf in comparison to that of the standard λ cdm evolution, and then we impose the observational bound on |δ/tf tf| to extract constraints on the involved parameters of the considered models. concerning the polynomial model, we show that the exponent parameter should be negative, while for the power-exponential model and the new hyperbolic tangent-power model we find that they pass the bbn constraints trivially. finally, we examine two dgp-like f(q) models, and we extract the bounds on their model parameters. since many gravitational modifications, although able to describe the late-time evolution of the universe, produce too-much modification at early times and thus fall to pass the bbn confrontation, the fact that f(q) gravity can safely pass the bbn constraints is an important advantage of this modified gravity class. | new models and big bang nucleosynthesis constraints in f(q) gravity |
quantum consistency suggests that any de sitter patch that lasts a number of hubble times that exceeds its gibbons-hawking entropy divided by the number of light particle species suffers an effect of quantum breaking. inclusion of other interactions makes the quantum break-time shorter. the requirement that this must not happen puts severe constraints on scalar potentials, essentially suppressing the self-reproduction regimes. in particular, it eliminates both local and global minima with positive energy densities and imposes a general upper bound on the number of e-foldings in any given hubble patch. consequently, maxima and other tachyonic directions must be curved stronger than the corresponding hubble parameter. we show that the key relations of the recently-proposed de sitter swampland conjecture follow from the de sitter quantum breaking bound. we give a general derivation and also illustrate this on a concrete example of $d$-brane inflation. we can say that string theory as a consistent theory of quantum gravity nullifies a positive vacuum energy in self-defense against quantum breaking. | quantum breaking bound on de sitter and swampland |
motivated by the large observed diversity in the properties of extragalactic extinction by dust, we reanalyze the cepheid calibration used to infer the hubble constant, h 0, from type ia supernovae, using cepheid data in 19 type ia supernova host galaxies from riess et al. and anchor data from riess et al. unlike the sh0es team, we do not enforce a fixed universal color-luminosity relation to correct the cepheid magnitudes. instead, we focus on a data-driven method, where the optical colors and near-infrared magnitudes of the cepheids are used to derive individual color-luminosity relations for each type ia supernova host and anchor galaxy. we present two different analyses, one based on wesenheit magnitudes, resulting in h 0 = 73.2 ± 1.3 km s-1 mpc-1, a 4.2σ tension with the value inferred from the cosmic microwave background. in the second approach, we calibrate an individual extinction law for each galaxy, with noninformative priors using color excesses, yielding h 0 = 73.9 ± 1.8 km s-1 mpc-1, in 3.4σ tension with the planck value. although the two methods yield similar results, in the latter approach, the hubble constants inferred from the individual cepheid absolute distance calibrator galaxies range from h 0 = 68.1 ± 3.5 km s-1 mpc-1 to h 0 = 76.7 ± 2.0 km s-1 mpc-1. taking the correlated nature of h 0 inferred from individual anchors into account, and allowing for individual extinction laws, the milky way anchor is in 2.1-3.1 σ tension with the ngc 4258 and large magellanic cloud anchors, depending on prior assumptions regarding the color-luminosity relations and the method used for quantifying the tension. | sensitivity of the hubble constant determination to cepheid calibration |
a search for narrow vector resonances decaying into quark-antiquark pairs is presented. the analysis is based on data collected in proton-proton collisions at √{s}=13 tev with the cms detector at the lhc, corresponding to an integrated luminosity of 35.9 fb-1. the hypothetical resonance is produced with sufficiently high transverse momentum that its decay products are merged into a single jet with two-prong substructure. a signal would be identified as a peak over a smoothly falling background in the distribution of the invariant mass of the jet, using novel jet substructure techniques. no evidence for such a resonance is observed within the mass range of 50-300 gev. upper limits at 95% confidence level are set on the production cross section, and presented in a mass-coupling parameter space. the limits further constrain simplified models of dark matter production involving a mediator interacting between quarks and dark matter particles through a vector or axial-vector current. in the framework of these models, the results are the most sensitive to date, extending for the first time the search region to masses below 100 gev. [figure not available: see fulltext.] | search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at √{s}=13 tev |
type ia supernovae, calibrated by classical distance ladder methods, can be used, in conjunction with galaxy survey two-point correlation functions, to empirically determine the size of the sound horizon r s. assumption of the λcdm model, together with data to constrain its parameters, can also be used to determine the size of the sound horizon. using a variety of cosmic microwave background (cmb) data sets to constrain λcdm parameters, we find the model-based sound horizon to be larger than the empirically determined one with a statistical significance of between 2σ and 3σ, depending on the data set. if reconciliation requires a change to the cosmological model, we argue that change is likely to be important in the two decades of scale factor evolution prior to recombination. future cmb observations will therefore likely be able to test any such adjustments; e.g., a third-generation cmb survey like spt-3g can achieve a threefold improvement in the constraints on r s in the λcdm model extended to allow additional light degrees of freedom. | sounds discordant: classical distance ladder and λcdm-based determinations of the cosmological sound horizon |
in anticipation of upcoming gravitational wave experiments, we provide a comprehensive overview of the spectra predicted by phase transitions triggered by states from a large variety of dark sector models. such spectra are functions of the quantum numbers and (self-) couplings of the scalar that triggers the dark phase transition. we classify dark sectors that give rise to a first order phase transition and perform a numerical scan over the thermal parameter space. we then characterize scenarios in which a measurement of a new source of gravitational waves could allow us to discriminate between models with differing particle content. | model discrimination in gravitational wave spectra from dark phase transitions |
we evaluate the effectiveness of early dark energy (ede) in addressing the hubble tension using data from the completed eboss survey, focusing on luminous red galaxies (lrgs), quasars (qsos), and emission line galaxies (elgs). we perform cosmological parameter measurements based on full shape analysis of the power spectrum of all three tracers. we conduct this full shape analysis with the effective field theory of large-scale structure (eftoflss). ede is known to strongly suffer from volume projection effects, which makes the interpretation of cosmological constraints challenging. to quantify the volume projection effects within an ede full shape analysis, we explore the impact of different prior choices on the nuisance parameters of eftoflss through an extensive mock study. we compare classical gaussian priors to the non-informative jeffreys prior, known to mitigate volume projection effects in $\lambda$cdm. our full shape analysis combines eboss and boss data with planck, external baryon acoustic oscillation (bao), pantheonplus, and sh0es supernova data. ede demonstrates to reduce the tension from $5.2\sigma$ to $3\sigma$ compared to $\lambda$cdm. the derived values at a 68\% credible interval with gaussian and jeffreys priors are $h_0=71.73_{-0.86}^{+0.82}$ km/s/mpc with $f_\mathrm{ede} = 0.1179_{-0.022}^{+0.025}$ and $h_0=72.03_{-0.87}^{+0.82}$ km/s/mpc with $f_\mathrm{ede} = 0.1399_{-0.022}^{+0.023}$, respectively. although the hubble tension is mitigated compared to $\lambda$cdm, the inclusion of eboss data amplifies the tension within ede from $2\sigma$ to $3\sigma$, in contrast to the full shape analysis of boss data with planck, external bao, pantheonplus, and sh0es. this highlights the significance of incorporating additional large-scale structure data in discussions concerning models aiming to resolve the hubble tension. | cosmological constraints on early dark energy from the full shape analysis of eboss dr16 |
for a cosmological first-order phase transition in the early universe, the associated stochastic gravitational wave background is usually dominated by sound waves from plasma fluid motions, which have been analytically modeled as a random superposition of freely propagating sound shells but with the force by the scalar field that produces the self-similar profile removed. in this letter, we propose a new analytic sound shell model by focusing on the forced propagating contribution from the initial collision stage of sound shells when their self-similar profiles are still maintained by the moving bubble walls. we reproduce the causal k3 scaling in the infrared consistent with numerical simulations, and also recover the broad dome in the power spectrum first observed in numerical simulations. the total sound waves should contain both contributions from forced collisions and free propagation of sound shells at early and late stages of the phase transition, respectively. | hydrodynamic sound shell model |
tidal disruption events (tdes) offer a unique way to study dormant black holes. while the number of observed tdes has grown thanks to the emergence of wide-field surveys in the past few decades, questions regarding the nature of the observed optical, uv, and x-ray emission remain. we present a uniformly selected sample of 30 spectroscopically classified tdes from the zwicky transient facility phase i survey operations with follow-up swift uv and x-ray observations. through our investigation into correlations between light-curve properties, we recover a shallow positive correlation between the peak bolometric luminosity and decay timescales. we introduce a new spectroscopic class of tde, tde-featureless, which are characterized by featureless optical spectra. the new tde-featureless class shows larger peak bolometric luminosities, peak blackbody temperatures, and peak blackbody radii. we examine the differences between the x-ray bright and x-ray faint populations of tdes in this sample, finding that x-ray bright tdes show higher peak blackbody luminosities than the x-ray faint subsample. this sample of optically selected tdes is the largest sample of tdes from a single survey yet, and the systematic discovery, classification, and follow-up of this sample allows for robust characterization of tde properties, an important stepping stone looking forward toward the rubin era. | the final season reimagined: 30 tidal disruption events from the ztf-i survey |
gravitational interferometers and cosmological observations of the cosmic microwave background offer us the prospect to probe the laws of gravity in the primordial universe. to study and interpret these datasets we need to know the possible graviton non-gaussianities. to this end, we derive the most general tree-level three-point functions (bispectra) for a massless graviton to all orders in derivatives, assuming scale invariance. instead of working with explicit lagrangians, we take a bootstrap approach and obtain our results using the recently derived constraints from unitarity, locality and the choice of vacuum. since we make no assumptions about de sitter boosts, our results capture the phenomenology of large classes of models such as the effective field theory of inflation and solid inflation. we present formulae for the infinite number of parity-even bispectra. remarkably, for parity-odd bispectra, we show that unitarity allows for only a handful of possible shapes: three for graviton-graviton-graviton, three for scalar-graviton-graviton and one for scalar-scalar-graviton, which we bootstrap explicitly. these parity-odd non-gaussianities can be large, for example in solid inflation, and therefore constitute a concrete and well-motivated target for future observations. | bootstrapping large graviton non-gaussianities |
we study axion-photon couplings in compactifications of type iib string theory. we find that these couplings are systematically suppressed compared to the inverse axion periodicity, as a result of two effects. first, couplings to the qed theta angle are suppressed for axion mass eigenstates that are light compared to the mass scale set by stringy instantons on the cycle supporting qed. second, in compactifications with many axions the intersection matrix is sparse, making kinetic mixing weak. we study the resulting phenomenology in an ensemble of $200{,}000$ toy models constructed from the kreuzer-skarke database up to the maximum hodge number $h^{1,1}=491$. we examine freeze-in production and decay of thermal axions, birefringence of the cosmic microwave background, x-ray spectrum oscillations, and constraints on the qcd axion from supernovae. we conclude that compactifications in this corner of the landscape involve many invisible axions, as well as a handful that may be detectable via photon couplings. | glimmers from the axiverse |
single-field models of inflation might lead to amplified scalar fluctuations on small scales due, for example, to a transient ultra-slow-roll phase. it was argued by kristiano $\&$ yokoyama in arxiv:2211.03395 that the enhanced amplitude of the scalar power spectrum on small scales has the potential to induce a sizeable 1-loop correction to the spectrum at large scales. in this work, we repeat the calculation for the 1-loop correction presented in arxiv:2211.03395. we closely follow their assumptions but evaluate the loop numerically. this allows us to consider both instantaneous and smooth transitions between the slow-roll and ultra-slow-roll phases. in particular, we generate models featuring realistic, smooth evolution from an analytic inflationary potential. we find that, upon fixing the amplitude of the peak in the power spectrum at short scales, the resulting 1-loop correction is not significantly reduced by considering a smooth evolution. in particular, for a power spectrum with a tree-level peak amplitude potentially relevant for small-scale phenomenology, e.g. primordial black hole production, the 1-loop correction on large scales is a few percent of the tree-level power spectrum. | numerical 1-loop correction from a potential yielding ultra-slow-roll dynamics |
we report a novel prediction from single-field inflation that even a tiny step in the inflaton potential can change our perception of primordial non-gaussianities of the curvature perturbation. our analysis focuses on the tail of probability distribution generated by an upward step transition between two stages of slow-roll evolution. the nontrivial background dynamics with off-attractor behavior is identified. by using a non-perturbative δn analysis, we explicitly show that a highly non-gaussian tail can be generated by a tiny upward step, even when the conventional nonlinearity parameters fnllocal, gnllocal, etc. remain small. with this example, we demonstrate for the first time the sensitive dependence of non-perturbative effects on the tail of probability distribution. our scenario has an inconceivable application to primordial black holes by either significantly boosting their abundance or completely forbidding their appearance. | one small step for an inflaton, one giant leap for inflation: a novel non-gaussian tail and primordial black holes |
we present nbodykit, an open-source, massively parallel python toolkit for analyzing large-scale structure (lss) data. using python bindings of the message passing interface, we provide parallel implementations of many commonly used algorithms in lss. nbodykit is both an interactive and scalable piece of scientific software, performing well in a supercomputing environment while still taking advantage of the interactive tools provided by the python ecosystem. existing functionality includes estimators of the power spectrum, two- and three-point correlation functions, a friends-of-friends grouping algorithm, mock catalog creation via the halo occupation distribution technique, and approximate n-body simulations via the fastpm scheme. the package also provides a set of distributed data containers, insulated from the algorithms themselves, that enables nbodykit to provide a unified treatment of both simulation and observational data sets. nbodykit can be easily deployed in a high-performance computing environment, overcoming some of the traditional difficulties of using python on supercomputers. we provide performance benchmarks illustrating the scalability of the software. the modular, component-based approach of nbodykit allows researchers to easily build complex applications using its tools. the package is extensively documented at http://nbodykit.readthedocs.io, which also includes an interactive set of example recipes for new users to explore. as open-source software, we hope nbodykit provides a common framework for the community to use and develop in confronting the analysis challenges of future lss surveys. | nbodykit: an open-source, massively parallel toolkit for large-scale structure |
we present the npipe processing pipeline, which produces calibrated frequency maps in temperature and polarization from data from the planck low frequency instrument (lfi) and high frequency instrument (hfi) using high-performance computers. npipe represents a natural evolution of previous planck analysis efforts, and combines some of the most powerful features of the separate lfi and hfi analysis pipelines. for example, following the lfi 2018 processing procedure, npipe uses foreground polarization priors during the calibration stage in order to break scanning-induced degeneracies. similarly, npipe employs the hfi 2018 time-domain processing methodology to correct for bandpass mismatch at all frequencies. in addition, npipe introduces several improvements, including, but not limited to: inclusion of the 8% of data collected during repointing manoeuvres; smoothing of the lfi reference load data streams; in-flight estimation of detector polarization parameters; and construction of maximally independent detector-set split maps. for component-separation purposes, important improvements include: maps that retain the cmb solar dipole, allowing for high-precision relative calibration in higher-level analyses; well-defined single-detector maps, allowing for robust co extraction; and hfi temperature maps between 217 and 857 ghz that are binned into 0'.9 pixels (nside = 4096), ensuring that the full angular information in the data is represented in the maps even at the highest planck resolutions. the net effect of these improvements is lower levels of noise and systematics in both frequency and component maps at essentially all angular scales, as well as notably improved internal consistency between the various frequency channels. based on the npipe maps, we present the first estimate of the solar dipole determined through component separation across all nine planck frequencies. the amplitude is (3366.6 ± 2.7) μk, consistent with, albeit slightly higher than, earlier estimates. from the large-scale polarization data, we derive an updated estimate of the optical depth of reionization of τ = 0.051 ± 0.006, which appears robust with respect to data and sky cuts. there are 600 complete signal, noise and systematics simulations of the full-frequency and detector-set maps. as a planck first, these simulations include full time-domain processing of the beam-convolved cmb anisotropies. the release of npipe maps and simulations is accompanied with a complete suite of raw and processed time-ordered data and the software, scripts, auxiliary data, and parameter files needed to improve further on the analysis and to run matching simulations. | planck intermediate results. lvii. joint planck lfi and hfi data processing |
ultralight axions (ulas) with masses in the range 1 0-33 ev ≤ma≤1 0-20 ev are motivated by string theory and might contribute to either the dark-matter or dark-energy densities of the universe. ulas could suppress the growth of structure on small scales, lead to an altered integrated sachs-wolfe effect on cosmic microwave-background (cmb) anisotropies, and change the angular scale of the cmb acoustic peaks. in this work, cosmological observables over the full ula mass range are computed and then used to search for evidence of ulas using cmb data from the wilkinson microwave anisotropy probe (wmap), planck satellite, atacama cosmology telescope, and south pole telescope, as well as galaxy clustering data from the wigglez galaxy-redshift survey. in the mass range 1 0-32 ev ≤ma≤1 0-25.5 ev , the axion relic-density ωa (relative to the total dark-matter relic density ωd) must obey the constraints ωa/ωd≤0.05 and ωah2≤0.006 at 95% confidence. for ma≳1 0-24 ev , ulas are indistinguishable from standard cold dark matter on the length scales probed, and are thus allowed by these data. for ma≲1 0-32 ev , ulas are allowed to compose a significant fraction of the dark energy. | a search for ultralight axions using precision cosmological data |
we measure and analyse the bispectrum of the final data release 12 (dr12), galaxy sample provided by the baryon oscillation spectroscopic survey, splitting by selection algorithm into lowz and cmass galaxies. the lowz sample contains 361 762 galaxies with an effective redshift of zlowz = 0.32, and the cmass sample contains 777 202 galaxies with an effective redshift of zcmass = 0.57. combining the power spectrum, measured relative to the line of sight, with the spherically averaged bispectrum, we are able to constrain the product of the growth of structure parameter, f, and the amplitude of dark matter density fluctuations, σ8, along with the geometric alcock-paczynski parameters, the product of the hubble constant and the comoving sound horizon at the baryon drag epoch, h(z)rs(zd), and the angular distance parameter divided by the sound horizon, da(z)/rs(zd). after combining pre-reconstruction rsd analyses of the power spectrum monopole, quadrupole and bispectrum monopole with post-reconstruction analysis of the bao power spectrum monopole and quadrupole, we find f(zlowz)σ8(zlowz) = 0.427 ± 0.056, da(zlowz)/rs(zd) = 6.60 ± 0.13, h(zlowz)rs(zd) = (11.55 ± 0.38)103 km s-1 for the lowz sample, and f(zcmass)σ8(zcmass) = 0.426 ± 0.029, da(zcmass)/rs(zd) = 9.39 ± 0.10, h(zcmass)rs(zd) = (14.02 ± 0.22)103 km s-1 for the cmass sample. we find general agreement with previous baryon oscillation spectroscopic survey dr11 and dr12 measurements. combining our data set with planck15 we perform a null test of general relativity through the γ-parametrization finding γ =0.733^{+0.068}_{-0.069}, which is ∼2.7σ away from the general relativity predictions. | the clustering of galaxies in the sdss-iii baryon oscillation spectroscopic survey: rsd measurement from the power spectrum and bispectrum of the dr12 boss galaxies |
we examine the circular velocity profiles of galaxies in λ cold dark matter (cdm) cosmological hydrodynamical simulations from the eagle and local groups projects and compare them with a compilation of observed rotation curves of galaxies spanning a wide range in mass. the shape of the circular velocity profiles of simulated galaxies varies systematically as a function of galaxy mass, but shows remarkably little variation at fixed maximum circular velocity. this is especially true for low-mass dark-matter-dominated systems, reflecting the expected similarity of the underlying cdm haloes. this is at odds with observed dwarf galaxies, which show a large diversity of rotation curve shapes, even at fixed maximum rotation speed. some dwarfs have rotation curves that agree well with simulations, others do not. the latter are systems where the inferred mass enclosed in the inner regions is much lower than expected for cdm haloes and include many galaxies where previous work claims the presence of a constant density `core'. the `cusp versus core' issue is thus better characterized as an `inner mass deficit' problem than as a density slope mismatch. for several galaxies, the magnitude of this inner mass deficit is well in excess of that reported in recent simulations where cores result from baryon-induced fluctuations in the gravitational potential. we conclude that one or more of the following statements must be true: (i) the dark matter is more complex than envisaged by any current model; (ii) current simulations fail to reproduce the diversity in the effects of baryons on the inner regions of dwarf galaxies; and/or (iii) the mass profiles of `inner mass deficit' galaxies inferred from kinematic data are incorrect. | the unexpected diversity of dwarf galaxy rotation curves |
new light, weakly-coupled particles are commonly invoked to address the persistent ∼ 4 σ anomaly in ( g-2) μand serve as mediators between dark and visible matter. if such particles couple predominantly to heavier generations and decay invisibly, much of their best-motivated parameter space is inaccessible with existing experimental techniques. in this paper, we present a new fixed-target, missing-momentum search strategy to probe invisibly decaying particles that couple preferentially to muons. in our setup, a relativistic muon beam impinges on a thick active target. the signal consists of events in which a muon loses a large fraction of its incident momentum inside the target without initiating any detectable electromagnetic or hadronic activity in downstream veto systems. we propose a two-phase experiment, m3 (muon missing momentum), based at fermilab. phase 1 with ∼ 1010 muons on target can test the remaining parameter space for which light invisibly-decaying particles can resolve the ( g - 2) μanomaly, while phase 2 with ∼ 1013 muons on target can test much of the predictive parameter space over which sub-gev dark matter achieves freeze-out via muon-philic forces, including gauged u(1) lμ- lτ . | m3: a new muon missing momentum experiment to probe ( g - 2) μand dark matter at fermilab |
we discuss quantum gravitational effects in einstein theory coupled to periodic axion scalars to analyze the viability of several proposals to achieve superplanckian axion periods (aka decay constants) and their possible application to large field inflation models. the effects we study correspond to the nucleation of euclidean gravitational instantons charged under the axion, and our results are essentially compatible with (but independent of) the weak gravity conjecture, as follows: single axion theories with superplanckian periods contain gravitational instantons inducing sizable higher harmonics in the axion potential, which spoil superplanckian inflaton field range. a similar result holds for multi-axion models with lattice alignment (like the kim-nilles-peloso model). finally, theories with n axions can still achieve a moderately superplanckian periodicity (by a factor) with no higher harmonics in the axion potential. the weak gravity conjecture fails to hold in this case due to the absence of some instantons, which are forbidden by a discrete zngauge symmetry. finally we discuss the realization of these instantons as euclidean d-branes in string compactifications. | transplanckian axions!? |
we present a morphological catalogue for ∼670 000 galaxies in the sloan digital sky survey in two flavours: t-type, related to the hubble sequence, and galaxy zoo 2 (gz2 hereafter) classification scheme. by combining accurate existing visual classification catalogues with machine learning, we provide the largest and most accurate morphological catalogue up to date. the classifications are obtained with deep learning algorithms using convolutional neural networks (cnns). we use two visual classification catalogues, gz2 and nair & abraham (2010), for training cnns with colour images in order to obtain t-types and a series of gz2 type questions (disc/features, edge-on galaxies, bar signature, bulge prominence, roundness, and mergers). we also provide an additional probability enabling a separation between pure elliptical (e) from s0, where the t-type model is not so efficient. for the t-type, our results show smaller offset and scatter than previous models trained with support vector machines. for the gz2 type questions, our models have large accuracy (>97 per cent), precision and recall values (>90 per cent), when applied to a test sample with the same characteristics as the one used for training. the catalogue is publicly released with the paper. | improving galaxy morphologies for sdss with deep learning |
we present global analyses of effective higgs portal dark matter models in the frequentist and bayesian statistical frameworks. complementing earlier studies of the scalar higgs portal, we use gambit to determine the preferred mass and coupling ranges for models with vector, majorana and dirac fermion dark matter. we also assess the relative plausibility of all four models using bayesian model comparison. our analysis includes up-to-date likelihood functions for the dark matter relic density, invisible higgs decays, and direct and indirect searches for weakly-interacting dark matter including the latest xenon1t data. we also account for important uncertainties arising from the local density and velocity distribution of dark matter, nuclear matrix elements relevant to direct detection, and standard model masses and couplings. in all higgs portal models, we find parameter regions that can explain all of dark matter and give a good fit to all data. the case of vector dark matter requires the most tuning and is therefore slightly disfavoured from a bayesian point of view. in the case of fermionic dark matter, we find a strong preference for including a cp-violating phase that allows suppression of constraints from direct detection experiments, with odds in favour of cp violation of the order of 100:1. finally, we present ddcalc 2.0.0, a tool for calculating direct detection observables and likelihoods for arbitrary non-relativistic effective operators. | global analyses of higgs portal singlet dark matter models using gambit |
light dark sectors in thermal contact with the standard model naturally produce the observed relic dark matter abundance and are the targets of a broad experimental search program. a key light dark sector model is the pseudo-dirac fermion with a dark photon mediator. the dynamics of the fermionic excited states are often neglected. we consider scenarios in which a nontrivial abundance of excited states is produced and their subsequent de-excitation yields interesting electromagnetic signals in direct detection experiments. we study three mechanisms of populating the excited state: a primordial excited fraction, a component up-scattered in the sun, and a component up-scattered in the earth. we find that the fractional abundance of primordial excited states is generically depleted to exponentially small fractions in the early universe. nonetheless, this abundance can produce observable signals in current dark matter searches. mev-scale dark matter with thermal cross sections and higher can be probed by down-scattering following excitation in the sun. up-scatters of gev-scale dark matter in the earth can give rise to signals in current and upcoming terrestrial experiments and x-ray observations. we comment on the possible relevance of these scenarios to the recent excess in xenon1t. | electromagnetic signals of inelastic dark matter scattering |
primordial black holes (pbhs) are supposed to form from the collapse of over-densed regions generated by large scalar curvature perturbations in the radiation dominated era. despite decades of various independent observations, the nature of dark matter (dm) remains highly puzzling. recently, pbh dm have aroused interest since they provide an attracting explanation to the merger events of binary black holes discovered by ligo/virgo and may play an important role on dm. during the formation of pbh, gravitational waves will be sourced by linear scalar perturbations at second-order, known as the scalar-induced gravitational waves (sigws), which provides a new way to hunt for pbh dm. this topic review mainly focus on the physics about sigws accompanying the formation of pbh dm. | a topic review on probing primordial black hole dark matter with scalar induced gravitational waves |
the ligo detection of the gravitational wave transient gw150914, from the inspiral and merger of two black holes with masses ≳30 m⊙, suggests a population of binary black holes with relatively high mass. this observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the universe, could be higher than previously expected. using the properties of gw150914, we estimate the energy density of such a background from binary black holes. in the most sensitive part of the advanced ligo and advanced virgo band for stochastic backgrounds (near 25 hz), we predict ωgw(f =25 hz )=1. 1-0.9+2.7×10-9 with 90% confidence. this prediction is robustly demonstrated for a variety of formation scenarios with different parameters. the differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. we conclude that this background is potentially measurable by the advanced ligo and advanced virgo detectors operating at their projected final sensitivity. | gw150914: implications for the stochastic gravitational-wave background from binary black holes |
we present a search for extragalactic fast blue optical transients (fbots) during phase i of the zwicky transient facility (ztf). we identify 38 candidates with durations above half-maximum light 1 day < t 1/2 < 12 days, of which 28 have blue (g - r ≲ -0.2 mag) colors at peak light. of the 38 transients (28 fbots), 19 (13) can be spectroscopically classified as core-collapse supernovae (sne): 11 (8) h- or he-rich (type ii/iib/ib) sne, 6 (4) interacting (type iin/ibn) sne, and 2 (1) h&he-poor (type ic/ic-bl) sne. two fbots (published previously) had predominantly featureless spectra and luminous radio emission: at2018lug (the koala) and at2020xnd (the camel). seven (five) did not have a definitive classification: at 2020bdh showed tentative broad hα in emission, and at 2020bot showed unidentified broad features and was 10 kpc offset from the center of an early-type galaxy. ten (eight) have no spectroscopic observations or redshift measurements. we present multiwavelength (radio, millimeter, and/or x-ray) observations for five fbots (three type ibn, one type iin/ibn, one type iib). additionally, we search radio-survey (vla and askap) data to set limits on the presence of radio emission for 24 of the transients. all x-ray and radio observations resulted in nondetections; we rule out at2018cow-like x-ray and radio behavior for five fbots and more luminous emission (such as that seen in the camel) for four additional fbots. we conclude that exotic transients similar to at2018cow, the koala, and the camel represent a rare subset of fbots and use ztf's sn classification experiments to measure the rate to be at most 0.1% of the local core-collapse sn rate. | a search for extragalactic fast blue optical transients in ztf and the rate of at2018cow-like transients |
dark matter is one of the greatest mysteries in physics. it interacts via gravity and composes most of our universe, but its elementary composition is unknown. we search for nongravitational interactions of axion-like dark matter with atomic spins using a precision quantum detector. the detector is composed of spin-polarized xenon gas that can coherently interact with a background dark matter field as it traverses through the galactic dark matter halo. conducting a 5-month-long search, we report on the first results of the noble and alkali spin detectors for ultralight coherent dark matter (nasduck) collaboration. we limit alp-neutron interactions in the mass range of 4 × 10 −15 to 4 × 10 −12 ev/ c 2 and improve upon previous terrestrial bounds by up to 1000-fold for masses above 4 × 10 −13 ev/ c 2 . we also set bounds on pseudoscalar dark matter models with quadratic coupling. bounds are set on ultralight dark matter and its interaction with neutrons using a floquet nmr quantum detector. | new constraints on axion-like dark matter using a floquet quantum detector |
we extend the calculation of dark matter direct detection rates via electronic transitions in general dielectric crystal targets, combining state-of-the-art density functional theory calculations of electronic band structures and wave functions near the band gap, with semianalytic approximations to include additional states farther away from the band gap. we show, in particular, the importance of all-electron reconstruction for recovering large momentum components of electronic wave functions, which, together with the inclusion of additional states, has a significant impact on direct detection rates, especially for heavy mediator models and at o (10 ev ) and higher energy depositions. applying our framework to silicon and germanium (that have been established already as sensitive dark matter detectors), we find that our extended calculations can appreciably change the detection prospects. our calculational framework is implemented in an open-source program exceed-dm (extended calculation of electronic excitations for direct detection of dark matter), to be released in an upcoming publication. | extended calculation of dark matter-electron scattering in crystal targets |
spurred by rich, multiwavelength observations and enabled by new simulations, ranging from cosmological to subparsec scales, the past decade has seen major theoretical progress in our understanding of the circumgalactic medium (cgm). we review key physical processes in the cgm. our conclusions include the following: <label>■</label>the properties of the cgm depend on a competition between gravity-driven infall and gas cooling. when cooling is slow relative to free fall, the gas is hot (roughly virial temperature), whereas the gas is cold (t ∼ 104 k) when cooling is rapid.<label>■</label>gas inflows and outflows play crucial roles, as does the cosmological environment. large-scale structure collimates cold streams and provides angular momentum. satellite galaxies contribute to the cgm through winds and gas stripping.<label>■</label>in multiphase gas, the hot and cold phases continuously exchange mass, energy, and momentum. the interaction between turbulent mixing and radiative cooling is critical. a broad spectrum of cold gas structures, going down to subparsec scales, arises from fragmentation, coagulation, and condensation onto gas clouds.<label>■</label>magnetic fields, thermal conduction, and cosmic rays can substantially modify how the cold and hot phases interact, although microphysical uncertainties are presently large.key open questions for future work include the mutual interplay between small-scale structure and large-scale dynamics, and how the cgm affects the evolution of galaxies. | key physical processes in the circumgalactic medium |
a number of anomalous results in short-baseline oscillation may hint at the existence of one or more light sterile neutrino states in the ev mass range and have triggered a wave of new experimental efforts to search for a definite signature of oscillations between active and sterile neutrino states. the present paper aims to provide a comprehensive review on the status of light sterile neutrino searches in mid-2019: we discuss not only the basic experimental approaches and sensitivities of reactor, source, atmospheric, and accelerator neutrino oscillation experiments but also the complementary bounds arising from direct neutrino mass experiments and cosmological observations. moreover, we review current results from global oscillation analyses that include the constraints set by running reactor and atmospheric neutrino experiments. they permit to set tighter bounds on the active-sterile oscillation parameters but as yet are not able to provide a definite conclusion on the existence of ev-scale sterile neutrinos. | status of light sterile neutrino searches |
we describe the design, manufacture, and performance of bare-fiber integral field units (ifus) for the sdss-iv survey mapping nearby galaxies at apache point observatory (manga) on the the sloan 2.5 m telescope at apache point observatory. manga is a luminosity-selected integral-field spectroscopic survey of 104 local galaxies covering 360-1030 nm at r∼ 2200. the ifus have hexagonal dense packing of fibers with packing regularity of 3 μm (rms), and throughput of 96 ± 0.5% from 350 nm to 1 μm in the lab. their sizes range from 19 to 127 fibers (3-7 hexagonal layers) using polymicro fbp 120:132:150 μm core:clad:buffer fibers to reach a fill fraction of 56%. high throughput (and low focal-ratio degradation (frd)) is achieved by maintaining the fiber cladding and buffer intact, ensuring excellent surface polish, and applying a multi-layer anti-reflection (ar) coating of the input and output surfaces. in operations on-sky, the ifus show only an additional 2.3% frd-related variability in throughput despite repeated mechanical stressing during plate plugging (however other losses are present). the ifus achieve on-sky throughput 5% above the single-fiber feeds used in sdss-iii/boss, attributable to equivalent performance compared to single fibers and additional gains from the ar coating. the manufacturing process is geared toward mass-production of high-multiplex systems. the low-stress process involves a precision ferrule with a hexagonal inner shape designed to lead inserted fibers to settle in a dense hexagonal pattern. the ferrule id is tapered at progressively shallower angles toward its tip and the final 2 mm are straight and only a few microns larger than necessary to hold the desired number of fibers. our ifu manufacturing process scales easily to accommodate other fiber sizes and can produce ifus with substantially larger fiber counts. to assure quality, automated testing in a simple and inexpensive system enables complete characterization of throughput and fiber metrology. future applications include larger ifus, higher fill factors with stripped buffer, de-cladding, and lenslet coupling. | the manga integral field unit fiber feed system for the sloan 2.5 m telescope |
hawking evaporation of primordial black holes (pbhs) can facilitate the generation of matter-antimatter asymmetry. we focus on ultra-low mass pbhs that briefly dominate the universe and evaporate before the big bang nucleosynthesis. we propose a novel test of this scenario by detecting its characteristic doubly peaked gravitational wave (gw) spectrum in future gw observatories. here the first order adiabatic perturbation from inflation and from the isocurvature perturbations due to pbh distribution, source tensor perturbations in second-order and lead to two peaks in the induced gw background. these resonant peaks are generated at the beginning of standard radiation domination in the presence of a prior pbh-dominated era. this unique gw spectral shape would provide a smoking gun signal of non-thermal baryogenesis from evaporating pbhs, which is otherwise impossible to test in laboratory experiments due to the very high energy scales involved or the feeble interaction of the dark sector with the visible sector. | doubly peaked induced stochastic gravitational wave background: testing baryogenesis from primordial black holes |
we study the properties of the stochastic gravitational wave background (sgwb) produced by domain walls (dws) during inflation without forming a network. we numerically simulate the dw production caused by a second-order phase transition and calculate the sgwb spectrum using a $1000\times1000\times1000$ lattice. we show that the sgwb can be observed directly by future terrestrial and spatial gravitational wave detectors and through the b-mode spectrum in cmb. this signal can also explain the common noise process observed by pulsar timing array experiments. with numerical simulations, we derive an empirical formula for the strength and qualitative features of the sgwb spectrum. the details of the sgwb spectrum also contain information about the later evolution of the universe. | gravitational waves produced by domain walls during inflation |
we compile a complete collection of reliable hubble parameter h(z) data to redshift z ≤ 2.36 and use them with the gaussian process method to determine continuous h(z) functions for various data subsets. from these continuous h(z)'s, summarizing across the data subsets considered, we find h 0 ∼ 67 ± 4 km s-1 mpc-1, more consistent with the recent lower values determined using a variety of techniques. in most data subsets, we see a cosmological deceleration-acceleration transition at 2σ significance, with the data subsets transition redshifts varying over 0.33< {z}da}< 1.0 at 1σ significance. we find that the flat-λcdm model is consistent with the h(z) data to a z of 1.5 to 2.0, depending on data subset considered, with 2σ deviations from flat-λcdm above this redshift range. using the continuous h(z) with baryon acoustic oscillation distance-redshift observations, we constrain the current spatial curvature density parameter to be {{{ω }}}k0=-0.03+/- 0.21, consistent with a flat universe, but the large error bar does not rule out small values of spatial curvature that are now under debate. | hubble parameter and baryon acoustic oscillation measurement constraints on the hubble constant, the deviation from the spatially flat λcdm model, the deceleration-acceleration transition redshift, and spatial curvature |
cosmological phase transitions proceed via the nucleation of bubbles that subsequently expand and collide. the resulting gravitational wave spectrum depends crucially on the bubble wall velocity. we use holography to compute the wall velocity from first principles in a strongly coupled, non-abelian, four-dimensional gauge theory. the wall velocity is determined dynamically in terms of the nucleation temperature. we verify that ideal hydrodynamics provides a good description of the system everywhere except near the wall. | bubble wall velocity from holography |
scattering of light dark matter with sub-ev energy deposition can be detected with collective excitations in condensed matter systems. when dark matter has spin-independent couplings to atoms or ions, it has been shown to efficiently excite phonons. here we show that, if dark matter couples to the electron spin, magnon excitations in materials with magnetic dipole order offer a promising detection path. we derive general formulae for single magnon excitation rates from dark matter scattering, and demonstrate as a proof of principle the projected reach of a yttrium iron garnet target for several dark matter models with spin-dependent interactions. this highlights the complementarity of various collective excitations in probing different dark matter interactions. | detecting light dark matter with magnons |
gas falling into a black hole (bh) from large distances is unaware of bh spin direction, and misalignment between the accretion disc and bh spin is expected to be common. however, the physics of tilted discs (e.g. angular momentum transport and jet formation) is poorly understood. using our new gpu-accelerated code h-amr, we performed 3d general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning bhs, at the highest resolution to date. we explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the bh, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the bh). if strong large-scale magnetic flux reaches the bh, it bends the inner few gravitational radii of the disc and jets into partial alignment with the bh spin. on longer time-scales, the simulated disc-jet system as a whole undergoes lense-thirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. when the disc turbulence is well resolved, our isolated discs spread out, causing both the alignment and precession to slow down. | formation of precessing jets by tilted black hole discs in 3d general relativistic mhd simulations |
accurately predicting the demographics of dark matter (dm) substructure is of paramount importance for many fields of astrophysics, including gravitational lensing, galaxy evolution, halo occupation modelling, and constraining the nature of dm. because of its strongly non-linear nature, dm substructure is typically modelled using n-body simulations, which reveal that large fractions of dm subhaloes undergo complete disruption. in this paper, we use both analytical estimates and idealized numerical simulations to investigate whether this disruption is mainly physical, due to tidal heating and stripping, or numerical (i.e. artificial). we show that, contrary to naive expectation, subhaloes that experience a tidal shock δe that exceeds the subhalo's binding energy, |eb|, do not undergo disruption, even when δe/|eb| is as large as 100. along the same line, and contrary to existing claims in the literature, instantaneously stripping matter from the outskirts of a dm subhalo also does not result in its complete disruption, even when the instantaneous remnant has positive binding energy. in addition, we show that tidal heating due to high-speed (impulsive) encounters with other subhaloes (`harassment') is negligible compared to the tidal effects due to the host halo. hence, we conclude that, in the absence of baryonic processes, the complete physical disruption of cdm substructure is extremely rare and that most disruption in numerical simulations therefore must be artificial. we discuss various processes that have been associated with numerical overmerging and conclude that inadequate force softening is the most likely culprit. | disruption of dark matter substructure: fact or fiction? |
new constraints are presented on the spin-dependent weakly-interacting-massive-particle- (wimp-)nucleon interaction from the pandax-ii experiment, using a data set corresponding to a total exposure of 3.3 ×104 kg day . assuming a standard axial-vector spin-dependent wimp interaction with <mml:mmultiscripts>xe 129 </mml:mmultiscripts> and <mml:mmultiscripts>xe 131 </mml:mmultiscripts> nuclei, the most stringent upper limits on wimp-neutron cross sections for wimps with masses above 10 gev /c2 are set in all dark matter direct detection experiments. the minimum upper limit of 4.1 ×10-41 cm2 at 90% confidence level is obtained for a wimp mass of 40 gev /c2 . this represents more than a factor of 2 improvement on the best available limits at this and higher masses. these improved cross-section limits provide more stringent constraints on the effective wimp-proton and wimp-neutron couplings. | spin-dependent weakly-interacting-massive-particle-nucleon cross section limits from first data of pandax-ii experiment |
within classically conformal models, the spontaneous breaking of scale invariance is usually associated to a strong first order phase transition that results in a gravitational wave background within the reach of future space-based interferometers. in this paper we study the case of the classically conformal gauged b-l model, analysing the impact of this minimal extension of the standard model on the dynamics of the electroweak symmetry breaking and derive its gravitational wave signature. particular attention is paid to the problem of vacuum stability and to the role of the qcd phase transition, which we prove responsible for concluding the symmetry breaking transition in part of the considered parameter space. finally, we calculate the gravitational wave signal emitted in the process, finding that a large part of the parameter space of the model can be probed by lisa. | phase transition and vacuum stability in the classically conformal b-l model |
the renormalization of the vacuum energy in quantum field theory (qft) is usually plagued with theoretical conundrums related not only with the renormalization procedure itself, but also with the fact that the final result leads usually to very large (finite) contributions incompatible with the measured value of λ in cosmology. as a consequence, one is bound to extreme fine-tuning of the parameters and so to sheer unnaturalness of the result and of the entire approach. we may however get over this adversity using a different perspective. herein, we compute the zero-point energy (zpe) for a nonminimally coupled (massive) scalar field in flrw spacetime using the off-shell adiabatic renormalization technique employed in previous work. the on-shell renormalized result first appears at sixth adiabatic order, so the calculation is rather cumbersome. the general off-shell result yields a smooth function ρvac(h ) made out of powers of the hubble rate and/or of its time derivatives involving different (even) adiabatic orders ∼hn (n =0 ,2 ,4 ,6 ,…) , i.e. it leads, remarkably enough, to the running vacuum model (rvm) structure. we have verified the same result from the effective action formalism and used it to find the β -function of the running quantum vacuum. no undesired contributions ∼m4 from particle masses appear and hence no fine-tuning of the parameters is needed in ρvac(h ) . furthermore, we find that the higher power ∼h6 could naturally drive rvm-inflation in the early universe. our calculation also elucidates in detail the equation of state of the quantum vacuum: it proves to be not exactly -1 and is moderately dynamical. the form of ρvac(h ) at low energies is also characteristic of the rvm and consists of an additive term (the so-called `cosmological constant') together with a small dynamical component ∼ν h2 (|ν |≪1 ). finally, we predict a slow (∼lnh ) running of newton's gravitational coupling g(h). the physical outcome of our semiclassical qft calculation is revealing: today's cosmic vacuum and the gravitational strength should be both mildly dynamical. | renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem |
precise measurements of the cosmic microwave background (cmb) power spectrum are in excellent agreement with the predictions of the standard λ cdm cosmological model. however, there is some tension between the value of the hubble parameter h0 inferred from the cmb and that inferred from observations of the universe at lower redshifts, and the unusually small value of the dark-energy density is a puzzling ingredient of the model. in this paper, we explore a scenario with a new exotic energy density that behaves like a cosmological constant at early times and then decays quickly at some critical redshift zc. an exotic energy density like this is motivated by some string-axiverse-inspired scenarios for dark energy. by increasing the expansion rate at early times, the very precisely determined angular scale of the sound horizon at decoupling can be preserved with a larger hubble constant. we find, however, that the planck temperature power spectrum tightly constrains the magnitude of the early dark-energy density and thus any shift in the hubble constant obtained from the cmb. if the reionization optical depth is required to be smaller than the planck 2016 2 σ upper bound τ ≲0.0774 , then early dark energy allows a hubble-parameter shift of at most 1.6 km s-1 mpc-1 (at zc≃1585 ), too small to fully alleviate the hubble-parameter tension. only if τ is increased by more than 5 σ can the cmb hubble parameter be brought into agreement with that from local measurements. in the process, we derive strong constraints to the contribution of early dark energy at the time of recombination—it can never exceed ∼2 % of the radiation/matter density for 10 ≲zc≲1 05 . | dark energy at early times, the hubble parameter, and the string axiverse |
we study a coupled quintessence model with pure momentum exchange and present the effects of such an interaction on the cosmic microwave background (cmb) and matter power spectrum. for a wide range of negative values of the coupling parameter β structure growth is suppressed and the model can reconcile the tension between cosmic microwave background observations and structure growth inferred from cluster counts. we find that this model is as good as λ cdm for cmb and baryon acoustic oscillation data, while the addition of cluster data makes the model strongly preferred, improving the best-fit χ2 value by more than 16. | reconciling cmb and structure growth measurements with dark energy interactions |
inflation correlators with one-loop massive exchange encode rich information about the dynamics of the massive loop particles. their nonanalytic behavior in certain soft limits leads to characteristic oscillatory pattern, which is the leading signal of many particle models of cosmological collider physics. in this work, we investigate systematically such nonanalyticity for arbitrary one-particle-irreducible (1pi) one-loop correlators in various soft limits. with the partial mellin-barnes representation, we present and prove a factorization theorem and a cutting rule for arbitrary 1pi one-loop inflation correlators, which is reminiscent of the on-shell cutting rule for flat-space scattering amplitudes. we also show how to understand this factorization theorem from the viewpoint of operator product expansion on the future boundary. as an application of the one-loop factorization theorem, we derive new analytic and exact formulae for nonlocal cosmological collider signals for massive one-loop four-point inflation correlators of all possible 1pi topologies, including the bubble, the triangle, and the box graphs. finally, we show how to push the computation of nonlocal signals to higher orders in the momentum ratio. | inflation correlators at the one-loop order: nonanalyticity, factorization, cutting rule, and ope |
a rather minimal possibility is that dark matter consists of the gauge bosons of a spontaneously broken symmetry. here we explore the possibility of detecting the gravitational waves produced by the phase transition associated with such breaking. concretely, we focus on the scenario based on an su(2) dgroup and argue that it is a case study for the sensitivity of future gravitational wave observatories to phase transitions associated with dark matter. this is because there are few parameters and those fixing the relic density also determine the effective potential establishing the strength of the phase transition. particularly promising for lisa and even the einstein telescope is the super-cool dark matter regime, with dm masses above o (100) tev, for which we find that the gravitational wave signal is notably strong. in our analysis, we include the effect of astrophysical foregrounds, which are often ignored in the context of phase transitions. | strong gravitational radiation from a simple dark matter model |
the ligo and virgo interferometers have so far provided 11 gravitational-wave (gw) observations of black-hole binaries. similar detections are bound to become very frequent in the near future. with the current and upcoming wealth of data, it is possible to confront specific formation models with observations. we investigate here whether current data are compatible with the hypothesis that ligo/virgo black holes are of primordial origin. we compute in detail the mass and spin distributions of primordial black holes (pbhs), their merger rates, the stochastic background of unresolved coalescences, and confront them with current data from the first two observational runs, also including the recently discovered gw190412. we compute the best-fit values for the parameters of the pbh mass distribution at formation that are compatible with current gw data. in all cases, the maximum fraction of pbhs in dark matter is constrained by these observations to be f pbh≈ few× 10-3. we discuss the predictions of the pbh scenario that can be directly tested as new data become available. in the most likely formation scenarios where pbhs are born with negligible spin, the fact that at least one of the components of gw190412 is moderately spinning is incompatible with a primordial origin for this event, unless accretion or hierarchical mergers are significant. in the absence of accretion, current non-gw constraints already exclude that ligo/virgo events are all of primordial origin, whereas in the presence of accretion the gw bounds on the pbh abundance are the most stringent ones in the relevant mass range. a strong phase of accretion during the cosmic history would favour mass ratios close to unity, and a redshift-dependent correlation between high masses, high spins and nearly-equal mass binaries, with the secondary component spinning faster than the primary. finally, we highlight that accretion can play an important role to relax current constraints on the pbh abundance, which calls for a better modelling of the mass and angular momentum accretion rates at redshift 0zlesssim3. | primordial black holes confront ligo/virgo data: current situation |
aims: the erosita final equatorial-depth survey has been carried out during the performance verification phase of the spectrum-roentgen-gamma/erosita telescope and was completed in november 2019. this survey is designed to provide the first erosita-selected sample of clusters and groups and to test the predictions for the all-sky survey in the context of cosmological studies with clusters of galaxies.methods: in the area of ~140 square degrees covered by efeds, 542 candidate clusters and groups of galaxies were detected as extended x-ray sources with the esass source detection algorithm. we performed imaging and spectral analysis of the 542 cluster candidates with erosita x-ray data and studied the properties of the sample.results: we provide the catalog of candidate galaxy clusters and groups detected by erosita in the efeds field down to a flux of ~10-14 erg s-1 cm-2 in the soft band (0.5-2 kev) within 1'. the clusters are distributed in the redshift range ɀ = [0.01, 1.3] with a median redshift ɀmedian = 0.35. with erosita x-ray data, we measured the temperature of the intracluster medium within two radii, 300 kpc and 500 kpc, and constrained the temperature with >2σ confidence level for ~1/5 (102 out of 542) of the sample. the average temperature of these clusters is ~2 kev. radial profiles of flux, luminosity, electron density, and gas mass were measured from the precise modeling of the imaging data. the selection function, the purity, and the completeness of the catalog are examined and discussed in detail. the contamination fraction is ~1/5 in this sample and is dominated by misidentified point sources. the x-ray luminosity function of the clusters agrees well with the results obtained from other recent x-ray surveys. we also find 19 supercluster candidates in this field, most of which are located at redshifts between 0.1 and 0.5, including one cluster at ɀ ~ 0.36 that was presented previously.conclusions: the efeds cluster and group catalog at the final erass equatorial depth provides a benchmark proof of concept for the erosita all-sky survey extended source detection and characterization. we confirm the excellent performance of erosita for cluster science and expect no significant deviations from our pre-launch expectations for the final all-sky survey. the full cluster catalog is only available at the cds via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/661/a2 | the erosita final equatorial-depth survey (efeds). catalog of galaxy clusters and groups |
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