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  • Revisiting supernova constraints on a light CP-even scalar
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    P.S. Bhupal Dev, Rabindra N. Mohapatra and Yongchao Zhang

    A light CP-even Standard Model (SM) gauge-singlet scalar S can be produced abundantly in the supernova core, via the nucleon bremsstrahlung process N N → N N S , due to its mixing with the SM Higgs boson. Including the effective S coupling to both nucleons and the pion mediators, we evaluate the production amplitude for the S particle and point out a key difference with the well-known light CP-odd

    更新日期:2020-08-04
  • Attractors, bifurcations and curvature in multi-field inflation
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Perseas Christodoulidis, Diederik Roest and Evangelos I. Sfakianakis

    Recent years have seen the introduction of various multi-field inflationary scenarios in which the curvature and geodesics of the scalar manifold play a crucial role. We outline a simple description that unifies these different proposals and discuss their stability criteria. We demonstrate how the underlying dynamics is governed by an effective potential, whose critical points and bifurcations determine

    更新日期:2020-08-04
  • Machine learning meets the redshift evolution of the CMB temperature
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Rubén Arjona

    We present a model independent and non-parametric reconstruction with a Machine Learning algorithm of the redshift evolution of the Cosmic Microwave Background (CMB) temperature from a wide redshift range z ##IMG## [https://ej.iop.org/icons/Entities/in.gif] {in} [0,3] without assuming any dark energy model, an adiabatic universe or photon number conservation. In particular we use the genetic algorithms

    更新日期:2020-08-04
  • Primordial dark matter from curvature induced symmetry breaking
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Laura Laulumaa, Tommi Markkanen and Sami Nurmi

    We demonstrate that adiabatic dark matter can be generated by gravity induced symmetry breaking during inflation. We study a Z 2 symmetric scalar singlet that couples to other fields only through gravity and for which the symmetry is broken by the spacetime curvature during inflation when the non-minimal coupling ξ is negative. We find that the symmetry breaking leads to the formation of adiabatic

    更新日期:2020-08-04
  • What can we learn by combining the skew spectrum and the power spectrum?
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Ji-Ping Dai, Licia Verde and Jun-Qing Xia

    Clustering of the large scale structure provides complementary information to the measurements of the cosmic microwave background anisotropies through power spectrum and bispectrum of density perturbations. Extracting the bispectrum information, however, is more challenging than it is from the power spectrum due to the complex models and the computational cost to measure the signal and its covariance

    更新日期:2020-08-04
  • Big Bounce Baryogenesis
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Neil D. Barrie

    We explore the possibility of an Ekpyrotic contraction phase harbouring a mechanism for Baryogenesis. A Chern-Simons coupling between the fast-rolling Ekpyrotic scalar and the Standard Model Hypercharge gauge field enables the generation of a non-zero helicity during the contraction phase. The baryon number subsequently produced at the Electroweak Phase Transition is consistent with observation for

    更新日期:2020-08-04
  • A null test of the equivalence principle using relativistic effects in galaxy surveys
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Camille Bonvin, Felipe Oliveira Franco and Pierre Fleury

    The weak equivalence principle is one of the cornerstone of general relativity. Its validity has been tested with impressive precision in the Solar System, with experiments involving baryonic matter and light. However, on cosmological scales and when dark matter is concerned, the validity of this principle is still unknown. In this paper we construct a null test that probes the validity of the equivalence

    更新日期:2020-08-04
  • Accessing the axion via compact object binaries
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-03
    Michael Kavic, Steven L. Liebling, Matthew Lippert and John H. Simonetti

    Black holes in binaries with other compact objects can provide natural venues for indirect detection of axions or other ultralight fields. The superradiant instability associated with a rapidly spinning black hole leads to the creation of an axion cloud which carries energy and angular momentum from the black hole. This cloud will then decay via gravitational wave emission. We show that the energy

    更新日期:2020-08-04
  • Generating PBHs and small-scale GWs in two-field models of inflation
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-08-02
    Matteo Braglia, Dhiraj Kumar Hazra, Fabio Finelli, George F. Smoot, L. Sriramkumar and Alexei A. Starobinsky

    Primordial black holes (PBHs) generated by gravitational collapse of large primordial overdensities can be a fraction of the observed dark matter. In this paper, we introduce a mechanism to produce a large peak in the primordial power spectrum (PPS) in two-field inflationary models characterized by two stages of inflation based on a large non-canonical kinetic coupling. This mechanism is generic to

    更新日期:2020-08-03
  • Probing cosmic strings with gravitational-wave fringe
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-30
    Sunghoon Jung and TaeHun Kim

    Cosmic strings are important remnants of early-Universe phase transitions. We show that they can be probed by Gravitational Waves (GWs) from compact binary mergers. If such chirping GW passes by a cosmic string, it is gravitationally lensed and left with a characteristic signal of the lensing—the GW fringe. It is observable naturally through the frequency chirping of GWs. This allows to probe cosmic

    更新日期:2020-07-31
  • A consistent model of non-singular Schwarzschild black hole in loop quantum gravity and its quasinormal modes
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-30
    Mariam Bouhmadi-López, Suddhasattwa Brahma, Che-Yu Chen, Pisin Chen and Dong-han Yeom

    We investigate the interior structure, perturbations, and the associated quasinormal modes of a quantum black hole model recently proposed by Bodendorfer, Mele, and Münch (BMM). Within the framework of loop quantum gravity, the quantum parameters in the BMM model are introduced through polymerization, consequently replacing the Schwarzschild singularity with a spacelike transition surface. By treating

    更新日期:2020-07-31
  • Testing non-minimally coupled BEC dark matter with gravitational waves
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-30
    Dimitar Ivanov and Stefano Liberati

    We study the phenomenology associated to non-minimally coupled dark matter. In particular, we consider the model where the non-minimal coupling arises from the formation of relativistic Bose-Einstein condensates in high density regions of dark matter [1]. This non-minimal coupling is of Horndeski type and leads to a local modification of the speed of gravity with respect to the speed of light. Therefore

    更新日期:2020-07-31
  • Merger of dark matter axion clumps and resonant photon emission
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-30
    Mark P. Hertzberg, Yao Li and Enrico D. Schiappacasse

    A portion of light scalar dark matter, especially axions, may organize into gravitationally bound clumps (stars) and be present in large number in the galaxy today. It is therefore of utmost interest to determine if there are novel observational signatures of this scenario. Work has shown that for moderately large axion-photon couplings, such clumps can undergo parametric resonance into photons, for

    更新日期:2020-07-31
  • Quantum effects in Palatini Higgs inflation
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-30
    Mikhail Shaposhnikov, Andrey Shkerin and Sebastian Zell

    We study quantum effects in Higgs inflation in the Palatini formulation of gravity, in which the metric and connection are treated as independent variables. We exploit the fact that the cutoff, above which perturbation theory breaks down, is higher than the scale of inflation. Unless new physics above the cutoff leads to unnaturally large corrections, we can directly connect low-energy physics and

    更新日期:2020-07-31
  • Why the mean mass of primordial black hole distribution is close to 10 M ⊙
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-29
    A. Dolgov and K. Postnov

    It is shown that a mechanism of PBH formation from high-baryon bubbles with log-normal mass spectrum naturally leads to the central mass of the PBH distribution close to ten solar masses independently of the model details. This result is in good agreement with observations.

    更新日期:2020-07-30
  • The stabilizing effect of gravity made simple
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-28
    J.R. Espinosa

    A new approach to vacuum decay in quantum field theory, based on a simple variational formulation in field space using a tunneling potential, is ideally suited to study the effects of gravity on such decays. The method allows to prove in new and simple ways many results, among others, that gravitational corrections tend to make Minkowski or Anti de Sitter false vacua more stable semiclassically or

    更新日期:2020-07-29
  • Consistent modeling of velocity statistics and redshift-space distortions in one-loop perturbation theory
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-28
    Shi-Fan Chen, Zvonimir Vlah and Martin White

    The peculiar velocities of biased tracers of the cosmic density field contain important information about the growth of large scale structure and generate anisotropy in the observed clustering of galaxies. Using N-body data, we show that velocity expansions for halo redshift-space power spectra are converged at the percent-level at perturbative scales for most line-of-sight angles μ when the first

    更新日期:2020-07-29
  • Constraining the cosmological evolution of scalar-tensor theories with local measurements of the time variation of G
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-28
    Clare Burrage and Johannes Dombrowski

    We determine the conditions for which the constraints from lunar laser ranging on the time evolution of the local gravitational constant can be extrapolated to impose constraints on the time evolution of the cosmological gravitational constant in scalar-tensor theories of modified gravity. We allow for the possibility that the scalar-tensor theories are non-linear and contain a screening mechanism

    更新日期:2020-07-29
  • New measures to test modified gravity cosmologies
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-27
    Jiro Matsumoto, Teppei Okumura and Misao Sasaki

    The observed accelerated expansion of the Universe may be explained by dark energy or the breakdown of general relativity (GR) on cosmological scales. When the latter case, a modified gravity scenario, is considered, it is often assumed that the background evolution is the same as the ΛCDM model but the density perturbation evolves differently. In this paper, we investigate more general classes of

    更新日期:2020-07-28
  • Rotating black holes in Eddington-inspired Born-Infeld gravity: an exact solution
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-27
    Merce Guerrero, Gerardo Mora-Pérez, Gonzalo J. Olmo, Emanuele Orazi and Diego Rubiera-Garcia

    We find an exact, rotating charged black hole solution within Eddington-inspired Born-Infeld gravity. To this end we employ a recently developed correspondence or mapping between modified gravity models built as scalars out of contractions of the metric with the Ricci tensor, and formulated in metric-affine spaces (Ricci-Based Gravity theories) and General Relativity. This way, starting from the Kerr-Newman

    更新日期:2020-07-28
  • Model independent measurement of the growth rate from the consistency relations of the LSS
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-26
    Marco Marinucci, Takahiro Nishimichi and Massimo Pietroni

    The consistency relations for the large scale structure provide a link between the amplitude of baryonic acoustic oscillations in the squeezed bispectrum (BS) and in the power spectrum (PS). This relation depends on the large scale bias of the considered tracer, b α , and on the growth rate of structures, f . Remarkably, originating from basic symmetry principles, this relation is exact and independent

    更新日期:2020-07-27
  • Model-independent energy budget of cosmological first-order phase transitions—A sound argument to go beyond the bag model
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-26
    Felix Giese, Thomas Konstandin and Jorinde van de Vis

    We study the energy budget of a first-order cosmological phase transition, which is an important factor in the prediction of the resulting gravitational wave spectrum. Formerly, this analysis was based mostly on simplified models as for example the bag equation of state. Here, we present a model-independent approach that is exact up to the temperature dependence of the speed of sound in the broken

    更新日期:2020-07-27
  • Gravitational decoherence of dark matter
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-26
    Itamar Allali and Mark P. Hertzberg

    Decoherence describes the tendency of quantum sub-systems to dynamically lose their quantum character. This happens when the quantum sub-system of interest interacts and becomes entangled with an environment that is traced out. For ordinary macroscopic systems, electromagnetic and other interactions cause rapid decoherence. However, dark matter (DM) may have the unique possibility of exhibiting naturally

    更新日期:2020-07-27
  • Classical decay rates of oscillons
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-26
    Hong-Yi Zhang, Mustafa A. Amin, Edmund J. Copeland, Paul M. Saffin and Kaloian D. Lozanov

    Oscillons are extremely long-lived, spatially-localized field configurations in real-valued scalar field theories that slowly lose energy via radiation of scalar waves. Before their eventual demise, oscillons can pass through (one or more) exceptionally stable field configurations where their decay rate is highly suppressed. We provide an improved calculation of the non-trivial behavior of the decay

    更新日期:2020-07-27
  • Rotating black holes in 4 D Einstein-Gauss-Bonnet gravity and its shadow
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-23
    Rahul Kumar and Sushant G. Ghosh

    Recently there has been a surge of interest in regularizing,a D → 4 limit of, the Einstein-Gauss-Bonnet (EGB) gravity, and the resulting regularized 4 D EGB gravity has nontrivial dynamics. The theory admits spherically symmetric black holes generalizing the Schwarzschild black holes. We consider the rotating black hole in regularized 4 D EGB gravity and discuss their horizon properties and shadow

    更新日期:2020-07-24
  • Gravitational waves from first-order cosmological phase transitions: lifetime of the sound wave source
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-22
    John Ellis, Marek Lewicki and José Miguel No

    We survey systematically the general parametrisations of particle-physics models for a first-order phase transition in the early universe, including models with polynomial potentials both with and without barriers at zero temperature, and Coleman-Weinberg-like models with potentials that are classically scale-invariant. We distinguish three possibilities for the transition—detonations, deflagrations

    更新日期:2020-07-23
  • Compensated isocurvature perturbations in the galaxy power spectrum
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-22
    Alexandre Barreira, Giovanni Cabass, Kaloian D. Lozanov and Fabian Schmidt

    We investigate the potential of the galaxy power spectrum to constrain compensated isocurvature perturbations (CIPs), primordial fluctuations in the baryon density that are compensated by fluctuations in CDM density to ensure an unperturbed total matter density. We show that CIPs contribute to the galaxy overdensity at linear order, and if they are close to scale-invariant, their effects are nearly

    更新日期:2020-07-23
  • The likelihood for LSS: stochasticity of bias coefficients at all orders
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-22
    Giovanni Cabass and Fabian Schmidt

    In the EFT of biased tracers the noise field ##IMG## [https://ej.iop.org/icons/Entities/epsilon.gif] {epsilon} g is not exactly uncorrelated with the nonlinear matter field δ. Its correlation with δ is effectively captured by adding stochasticities to each bias coefficient. We show that if these stochastic fields are Gaussian (the impact of their non-Gaussianity being subleading on quasi-linear scales

    更新日期:2020-07-23
  • Examining the weak cosmic censorship conjecture of RN-AdS black holes via the new version of the gedanken experiment
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-22
    Xin-Yang Wang and Jie Jiang

    Based on the new version of the gedanken experiment proposed by Sorce and Wald, we investigate the weak cosmic censorship conjecture (WCCC) for Reissner-Nordström-AdS (RN-AdS) black holes under the second-order approximation of the perturbation that comes from the matter fields. First of all, we propose that the cosmological constant is a portion of the matter fields. It means that the cosmological

    更新日期:2020-07-23
  • The n -point streaming model: how velocities shape correlation functions in redshift space
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    Joseph Kuruvilla and Cristiano Porciani

    Starting from first principles, we derive the fundamental equations that relate the n -point correlation functions in real and redshift space. Our result generalises the so-called `streaming model' to higher-order statistics: the full n -point correlation in redshift-space is obtained as an integral of its real-space counterpart times the joint probability density of n −1 relative line-of-sight peculiar

    更新日期:2020-07-21
  • Modeling relativistic contributions to the halo power spectrum dipole
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    Florian Beutler and Enea Di Dio

    We study the power spectrum dipole of an N-body simulation which includes relativistic effects through ray-tracing and covers the low redshift Universe up to z max = 0.465 (RayGalGroup simulation). We model relativistic corrections as well as wide-angle, evolution, window and lightcone effects. Our model includes all relativistic corrections up to third-order including third-order bias expansion. We

    更新日期:2020-07-21
  • String gases and the swampland
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    Samuel Laliberte and Robert Brandenberger

    In this paper, we study some aspects of moduli stabilization using string gases in the context of the Swampland. In the framework which we derive, the matter Lagrangian for string gases yields a potential for the size moduli which satisfies the de Sitter conjecture with the condition|∇ V |/ V ≥ 1/√ p 1/ M p , where p is the number of compactified dimensions. Moreover, the moduli find themselves stabilized

    更新日期:2020-07-21
  • How Gaussian can the sky be? Primordial non-Gaussianity from quantum information
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    César Gómez and Raul Jimenez

    Using the quantum information picture to describe the early universe as a time dependent quantum density matrix, with time playing the role of a stochastic variable, we compute the non-gaussian features in the distribution of primordial fluctuations. We use a quasi de Sitter model to compute the corresponding quantum Fisher information function as the second derivative of the relative entanglement

    更新日期:2020-07-21
  • Synergies across the spectrum for particle dark matter indirect detection: how HI intensity mapping meets gamma rays
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    Elena Pinetti, Stefano Camera, Nicolao Fornengo and Marco Regis

    Neutral hydrogen (HI) intensity mapping traces the large-scale distribution of matter in the Universe and therefore should correlate with the gamma-ray emission originated from particle dark matter annihilation or from active galactic nuclei and star-forming galaxies, since the related processes occur in the same cosmic structures hosting HI. In this paper, we derive the cross-correlation signal between

    更新日期:2020-07-21
  • Soundness of dark energy properties
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-20
    Eleonora Di Valentino, Stefano Gariazzo, Olga Mena and Sunny Vagnozzi

    Type Ia Supernovae (SNeIa) used as standardizable candles have been instrumental in the discovery of cosmic acceleration, usually attributed to some form of dark energy (DE). Recent studies have raised the issue of whether intrinsic SNeIa luminosities might evolve with redshift. While the evidence for cosmic acceleration is robust to this possible systematic, the question remains of how much the latter

    更新日期:2020-07-21
  • Anisotropic instability in a higher order gravity theory
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-15
    Masroor C. Pookkillath, Antonio De Felice and Alexei A. Starobinsky

    We study a metric cubic gravity theory considering odd-parity modes of linear inhomogeneous perturbations on a spatially homogeneous Bianchi type I manifold close to the isotropic de Sitter spacetime. We show that in the regime of small anisotropy, the theory possesses new degrees of freedom compared to General Relativity, whose kinetic energy vanishes in the limit of exact isotropy. From the mass

    更新日期:2020-07-16
  • Constraints on neutrino emission from nearby galaxies using the 2MASS redshift survey and IceCube
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-15
    M.G. Aartsen, M. Ackermann, J. Adams, J.A. Aguilar, M. Ahlers, M. Ahrens, C. Alispach, K. Andeen, T. Anderson, I. Ansseau, G. Anton, C. Argüelles, J. Auffenberg, S. Axani, P. Backes, H. Bagherpour, X. Bai, A. Balagopal V., A. Barbano, S.W. Barwick, B. Bastian, V. Baum, S. Baur, R. Bay, J.J. Beatty, K.-H. Becker, J. Becker Tjus, S. BenZvi, D. Berley, E. Bernardini, D.Z. Besson, G. Binder, D. Bindig

    The distribution of galaxies within the local universe is characterized by anisotropic features. Observatories searching for the production sites of astrophysical neutrinos can take advantage of these features to establish directional correlations between a neutrino dataset and overdensities in the galaxy distribution in the sky. The results of two correlation searches between a seven-year time-integrated

    更新日期:2020-07-16
  • Back-reaction in massless de Sitter QFTs: holography, gravitational DBI action and f(R) gravity
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-15
    Jewel K. Ghosh, Elias Kiritsis, Francesco Nitti and Lukas T. Witkowski

    We employ gauge-gravity duality to study the backreaction effect of 4-dimensional large- N quantum field theories on constant-curvature backgrounds, and in particular de Sitter space-time. The field theories considered are holographic QFTs, dual to RG flows between UV and IR CFTs. We compute the holographic QFT contribution to the gravitational effective action for 4d Einstein manifold backgrounds

    更新日期:2020-07-16
  • Bayesian methods for fitting Baryon Acoustic Oscillations in the Lyman-α forest
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Andrei Cuceu, Andreu Font-Ribera and Benjamin Joachimi

    We study and compare fitting methods for the Lyman-α (Lyα) forest 3D correlation function. We use the nested sampler PolyChord and the community code picca to perform a Bayesian analysis which we compare with previous frequentist analyses. By studying synthetic correlation functions, we find that the frequentist profile likelihood produces results in good agreement with a full Bayesian analysis. On

    更新日期:2020-07-15
  • Constraints on the spacetime dynamics of an early dark energy component
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Hasti Khoraminezhad, Matteo Viel, Carlo Baccigalupi and Maria Archidiacono

    We consider an Early Dark Energy (EDE) cosmological model, and perform an analysis which takes into account both background and perturbation effects via the parameters c 2 eff and c 2 vis , representing effective sound speed and viscosity, respectively. By using the latest available data we derive constraints on the amount of dark energy at early times and the present value of the equation of state

    更新日期:2020-07-15
  • The dark matter component of the Gaia radially anisotropic substructure
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Nassim Bozorgnia, Azadeh Fattahi, Carlos S. Frenk, Andrew Cheek, David G. Cerdeño, Facundo A. Gómez, Robert J.J. Grand and Federico Marinacci

    We study the properties of the dark matter component of the radially anisotropic stellar population recently identified in the Gaia data, using magneto-hydrodynamical simulations of Milky Way-like halos from the Auriga project. We identify 10 simulated galaxies that approximately match the rotation curve and stellar mass of the Milky Way. Four of these have an anisotropic stellar population reminiscent

    更新日期:2020-07-15
  • Resonant instability of axionic dark matter clumps
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Zihang Wang, Lijing Shao and Li-Xin Li

    Axion is a popular candidate for dark matter particles. Axionic dark matter may form Bose-Einstein condensate and may be gravitationally bound to form axion clumps. Under the presence of electromagnetic waves with frequencyω= m a / 2, where m a is the axion mass, a resonant enhancement may occur, causing an instability of the axion clumps. With analytical and numerical approaches, we study the resonant

    更新日期:2020-07-15
  • Updated results on neutrino mass and mass hierarchy from cosmology with Planck 2018 likelihoods
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Shouvik Roy Choudhury and Steen Hannestad

    In this work we update the bounds on∑ m ν from latest publicly available cosmological data and likelihoods using Bayesian analysis, while explicitly considering particular neutrino mass hierarchies. In the minimalΛCDM + ∑ m ν model with most recent CMB data from Planck 2018 TT,TE,EE, lowE, and lensing; and BAO data from BOSS DR12, MGS, and 6dFGS, we find that at 95% C.L. the bounds are:∑ m ν <0.12

    更新日期:2020-07-15
  • Growth of linear perturbations in a universe with superfluid dark matter
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-14
    Shreya Banerjee, Sayantani Bera and David F. Mota

    The Lambda-Cold Dark Matter (ΛCDM) model agrees with most of the cosmological observations, but has some hindrances from observed data at smaller scales such as galaxies. Recently, Berezhiani and Khoury proposed a new theory involving interacting superfluid dark matter with three model parameters in [1], which explains galactic dynamics with great accuracy. In the present work, we study the cosmological

    更新日期:2020-07-15
  • Modified cosmology through spacetime thermodynamics and Barrow horizon entropy
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Emmanuel N. Saridakis

    We present modified cosmological scenarios that arise from the application of the "gravity-thermodynamics" conjecture, using the Barrow entropy instead of the usual Bekenstein-Hawking one. The former is a modification of the black hole entropy due to quantum-gravitational effects that deform the black-hole horizon by giving it an intricate, fractal structure. We extract modified cosmological equations

    更新日期:2020-07-14
  • Scalar-tensor extension of natural inflation
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Guillem Simeon

    We show that embedding natural inflation in a more general scalar-tensor theory, with non-minimal couplings to the Ricci scalar and the kinetic term, alleviates the current tension of natural inflation with observational data. The coupling functions respect the periodicity of the potential and the characteristic shift symmetry ##IMG## [https://ej.iop.org/icons/Entities/phi.gif]{phi} → ##IMG## [https://ej

    更新日期:2020-07-14
  • Non-bouncing solutions in loop quantum cosmology
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Martin Bojowald

    According to the Belinskii-Khalatnikov-Lifshitz scenario, a collapsing universe approaching a spacelike singularity can be approximated by homogeneous cosmological dynamics, but only if asymptotically small spatial regions are considered. It is shown here that the relevant small-volume behavior in solvable models of loop quantum cosmology is crucially different from the large-volume behavior exclusively

    更新日期:2020-07-14
  • From matter to galaxies: general relativistic bias for the one-loop bispectrum
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Juan Calles, Lina Castiblanco, Jorge Noreña and Clément Stahl

    We write down the Lagrangian bias expansion in general relativity up to 4th order in terms of operators describing the curvature of an early-time hypersurface for comoving observers. They can be easily expanded in synchronous or comoving gauges. This is necessary for the computation of the one-loop halo bispectrum, where relativistic effects can be degenerate with a primordial non-Gaussian signal.

    更新日期:2020-07-14
  • Inflaton clusters and inflaton stars
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Jens C. Niemeyer and Richard Easther

    In a broad class of scenarios, inflation is followed by an extended era of matter-dominated expansion during which the inflaton condensate is nonrelativistic on subhorizon scales. During this phase density perturbations grow to the point of nonlinearity and collapse into bound structures. This epoch strongly resembles structure formation with ultra-light axion-like particles. This parallel permits

    更新日期:2020-07-14
  • Beyond the Standard Models with cosmic strings
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-13
    Yann Gouttenoire, Géraldine Servant and Peera Simakachorn

    We examine which information on the early cosmological history can be extracted from the potential measurement by third-generation gravitational-wave observatories of a stochastic gravitational wave background (SGWB) produced by cosmic strings. We consider a variety of cosmological scenarios breaking the scale-invariant properties of the spectrum, such as early long matter or kination eras, short intermediate

    更新日期:2020-07-14
  • Gravitational traces of broken gauge symmetries
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-12
    Aleksandr Azatov, Daniele Barducci and Francesco Sgarlata

    We investigate first-order phase transitions arising from hidden sectors, which are in thermal equilibrium with the Standard Model bath in the Early Universe. Focusing on two simplified scenarios, a higgsed U(1) and a two scalar singlet model, we show the impact of friction effects acting on the bubble walls on the gravitational wave spectra and the consequences for present and future interferometer

    更新日期:2020-07-13
  • The angular resolution of GRAPES-3 EAS array after improved timing and shower front curvature correction based on age and size
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-09
    V.B. Jhansi, S. Ahmad, M. Chakraborty, S.R. Dugad, S.K. Gupta, B. Hariharan, Y. Hayashi, P. Jagadeesan, A. Jain, P. Jain, S. Kawakami, H. Kojima, S. Mahapatra, P.K. Mohanty, S.D. Morris, P.K. Nayak, A. Oshima, D. Pattanaik, P.S. Rakshe, K. Ramesh, B.S. Rao, L.V. Reddy, S. Shibata, F. Varsi and M. Zuberi

    The angular resolution of an extensive air shower (EAS) array plays a critical role in determining its sensitivity for the detection of point γ-ray sources in the multi-TeV energy range. The GRAPES-3, an EAS array located at Ooty in India (11.4 o N, 76.7 o E, 2200 m altitude) is designed to study γ-rays in the TeV-PeV energy range. It comprises of a dense array of 400 plastic scintillators deployed

    更新日期:2020-07-10
  • Primordial black holes as dark matter and gravitational waves from single-field polynomial inflation
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-09
    Guillermo Ballesteros, Julián Rey, Marco Taoso and Alfredo Urbano

    We consider the possibility that the majority of dark matter in our Universe consists of black holes of primordial origin. We determine the conditions under which such black holes may have originated from a single-field model of inflation characterized by a quartic polynomial potential. We also explore the effect of higher-dimensional operators. The large power spectrum of curvature perturbations that

    更新日期:2020-07-10
  • Alleviating the H 0 and σ 8 anomalies with a decaying dark matter model
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-09
    Kanhaiya L. Pandey, Tanvi Karwal and Subinoy Das

    The Hubble tension between the ΛCDM-model-dependent prediction of the current expansion rate H 0 using Planck data and direct, model-independent measurements in the local universe from the SH0ES collaboration disagree at >3.5σ. Moreover, there exists a milder ~ 2σ tension between similar predictions for the amplitude S 8 of matter fluctuations and its measurement in the local universe. As explanations

    更新日期:2020-07-10
  • Illuminating the dark ages: cosmic backgrounds from accretion onto primordial black hole dark matter
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-08
    G. Hasinger

    The recent interpretation of cold dark matter as the sum of contributions of different mass Primordial Black Hole (PBH) families [1] could explain a number of so far unsolved astrophysical mysteries. Here I assume a realistic 10 −8 –10 10 M ⊙ PBH mass distribution providing the bulk of the dark matter, consistent with all observational constraints. I estimate the contribution of baryon accretion onto

    更新日期:2020-07-09
  • Axions in neutron star mergers
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-08
    Steven P. Harris, Jean-François Fortin, Kuver Sinha and Mark G. Alford

    Supernovae and cooling neutron stars have long been used to constrain the properties of axions, such as their mass and interactions with nucleons and other Standard Model particles. We investigate the prospects of using neutron star mergers as a similar location where axions can be probed in the future. We examine the impact axions would have on mergers, considering both the possibility that they free-stream

    更新日期:2020-07-09
  • Enlightening the dark ages with dark matter
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-08
    Katie Short, José Luis Bernal, Alvise Raccanelli, Licia Verde and Jens Chluba

    Constraints on dark matter annihilation or decay offer unique insights into the nature of dark matter. We illustrate how surveys dedicated to detect the highly redshifted 21 cm signal from the dark ages will offer a new window into properties of particle dark matter. The 21 cm intensity mapping signal and its fluctuations are sensitive to energy injection from annihilation or decay of long-lived particles

    更新日期:2020-07-09
  • Foreground cleaning and template-free stochastic background extraction for LISA
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-08
    Mauro Pieroni and Enrico Barausse

    Based on the rate of resolved stellar origin black hole and neutron star mergers measured by LIGO and Virgo, it is expected that these detectors will also observe an unresolved Stochastic Gravitational Wave Background (SGWB) by the time they reach design sensitivity. A background from the same class of sources also exists in the LISA band, which will be observable by LISA with signal-to-noise ratio

    更新日期:2020-07-09
  • Transient weak gravity in scalar-tensor theories
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-07
    Manuel Wittner, Giorgio Laverda, Oliver F. Piattella and Luca Amendola

    Sub-horizon perturbations in scalar-tensor theories have been shown to grow generically faster than in uncoupled models due to a positive, additive Yukawa force. In such cases, the amount of clustering becomes larger than in the standard cosmological model, exacerbating the observed tension in the σ 8 parameter. Here we show instead that in some simple cases of conformally coupled dark energy one can

    更新日期:2020-07-08
  • The singularity in mimetic Kantowski-Sachs cosmology
    J. Cosmol. Astropart. Phys. (IF 5.21) Pub Date : 2020-07-06
    Marco de Cesare, Sanjeev S. Seahra and Edward Wilson-Ewing

    The dynamics of the vacuum Kantowski-Sachs space-time are studied in the so-called limiting curvature mimetic gravity theory. It is shown that in this theory the vacuum Kantowski-Sachs space-time is always singular. While the departures from general relativity due to the limiting curvature mimetic theory do provide an upper bound on the magnitude of the expansion scalar, both its rate of oscillations

    更新日期:2020-07-07
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