In the context of non-standard cosmologies, an early matter-dominated (EMD) era can significantly alter the conventional dark matter (DM) genesis. In this work, we reexamine the impact of an EMD on the weakly- and feebly-interacting massive particle (WIMP and FIMP) paradigms. EMD eras significantly modify the genesis of DM because of the change in the Hubble expansion rate and the injection of entropy

We summarize and explain the current status of time variations of the electron mass in cosmology, showing that such variations allow for significant easing of the Hubble tension, from the current ∼ 5σ significance, down to between 3.4σ and 1.0σ significance, depending on the precise model and data. Electron mass variations are preferred by Cosmic Microwave Background (CMB) data in combination with

Using the effective field theory of quantum gravity at second order in curvature, we calculate quantum corrections to the metric of gravastars and the closely related dark energy stars. We find that the quantum corrections in the exterior region depend on the equation of state of the gravastar, thus providing an example of quantum gravitational hair. We continue by calculating the induced quantum corrections

This work elaborates on a detailed analysis of the novel characteristics of gravitational waves (GWs) generated by extreme mass-ratio inspirals (EMRIs) within the framework of modified gravity (MOG). Our study begins by exploring the geometrical and dynamical properties of the Kerr-MOG spacetime. We employ the numerical kludge (NK) method for waveform simulations and reveal that the parameter α, representing

Inflationary models equipped with Chern-Simons coupling between their axion and gauge sectors exhibit an array of interesting signals including a testable chiral gravitational wave spectrum. The energy injection in the gauge sector triggered by the rolling axion leads to a well-studied enhancement of gauge field fluctuations. These may in turn affect observables such as the scalar and tensor spectra

In a mean-field approximation within Kinetic Field Theory, it is possible to derive an accurate analytic expression for the power spectrum of present-day non-linear cosmic density fluctuations. It depends on the theory of gravity and the cosmological model via the expansion function of the background space-time, the growth factor derived from it, and the gravitational coupling strength, which may deviate

V-mode polarization of the cosmic microwave background is expected to be vanishingly small in the ΛCDM model and, hence, usually ignored. Nonetheless, several astrophysical effects, as well as beyond standard model physics could produce it at a detectable level. A realistic half-wave plate — an optical element commonly used in CMB experiments to modulate the polarized signal — can provide sensitivity

This paper calculates the stochastic gravitational wave background from dark binaries with finite-range attractive dark forces, complementing previous works which consider long-range dark forces. The finiteness of the dark force range can dramatically modify both the initial distributions and evolution histories of the binaries. The generated gravitational wave spectrum is enhanced in the intermediate

While pulsar timing array experiments have recently found evidence for the existence of a stochastic gravitational wave (GW) background, its origin is still unclear. If this background is of astrophysical origin, we expect the distribution of GW sources to follow the one of galaxies. Since galaxies are not perfectly isotropically distributed at large scales, but follow the cosmological large-scale

Primordial magnetic fields (PMFs) may explain observations of magnetic fields on extragalactic scales. They are most cleanly constrained by measurements of cosmic microwave background radiation (CMB) anisotropies. Their effects on cosmic recombination may even be at the heart of the resolution of the Hubble tension. We present the most detailed analysis of the effects of PMFs on cosmic recombination

We investigate loosely bound composite states made of dark matter, where the binding energy for constituent particles is considerably less than the constituent mass. We focus on models of nuclear and molecular dark matter, where constituents are separated by length scales larger than the inverse constituent mass, just like nuclei and atoms in the Standard Model. The cosmology, structure, and interactions

Axion-like particles may form a network of cosmic strings in the Universe today that can rotate the plane of polarization of cosmic microwave background (CMB) photons. Future CMB observations with improved sensitivity might detect this axion-string-induced birefringence effect, thereby revealing an as-yet unseen constituent of the Universe and offering a new probe of particles and forces that are beyond

We investigate the tidal response of Kerr black holes in four-dimensional spacetimes subjected to external gravitational fields. Using the Ernst formalism and Weyl coordinates, we analyze the non-linear tidal deformation of rotating black holes and demonstrate that their static tidal Love numbers vanish at all orders of the external tidal field. We also show that this result is intimately related to

We study a scenario in which the expansion of the Early Universe is driven by a hot hidden sector (HS) with an initial temperature T' that is significantly higher than that of the visible sector (VS), T' ≫ T. The latter is assumed to be made of Standard Model (SM) particles and our main focus is on the possibility that dark matter (DM) is part of the dominant HS and that its abundance is set by secluded

The origin of Galactic Cosmic Rays (GCRs) and the potential role of Supernova Remnants (SNRs) as cosmic-ray (CR) accelerators remain subjects of ongoing debate. To shed more light on this topic, we have studied the spectral shapes of two SNRs, RX J1713.7-3946 and HAWC J2227+610, performing simulations for the Cherenkov Telescope Array Observatory (CTAO). The previous multi-wavelength (MWL) analysis

Recent detections of a low-frequency gravitational wave background (GWB) from various pulsar-timing-array (PTA) observations have renewed the interest in the inspiraling supermassive black hole binaries (SMBHBs), whose population is believed to be the most promising candidate with possible generalizations from including either orbital eccentricity or dark matter (DM) spike. In this paper, we show that

We investigate the properties of low angular momentum, relativistic, viscous, advective accretion flows around rotating black holes that include shock waves in the presence of thermal conduction. We self-consistently solve the governing fluid equations to obtain the global transonic accretion solutions for a set of model parameters, namely energy (ℰ), angular momentum (λ), viscosity (α), conduction

We scrutinize the reported lensing anomaly of the CMB by considering several phenomenological modifications of the lensing consistency parameter, AL. Considering Planck spectra alone, we find statistically significant evidence for scale dependence (`running') of AL. We then demonstrate that the anomaly is entirely driven by Planck's low multipoles, ℓ ≤ 30. When these data points are excluded, a joint

We consider gravitational lensing of neutrinos in a black hole geometry that parametrizes departures from the Schwarzschild spacetime in the weak-field limit with plane-wave approximation. We use the Rezzolla-Zhidenko parametrization and apply the analysis to the effects of spatial curvature deviations from GR to a hypothetical system with a central object of mass of the order of a solar mass and a

Stage-IV large scale structure surveys are promising probes of gravity on cosmological scales. Due to the vast model-space in the modified gravity literature, model-independent parameterisations represent useful and scalable ways to test extensions of ΛCDM. In this work we use a recently validated approach of computing the non-linear 3 × 2 pt observables in modified gravity models with a time-varying

Astronomical and cosmological observations indicate that dark matter should interact very weakly with the electromagnetic radiation. Nevertheless, the existence of such interactions is not precluded by observations nor by theoretical considerations. A promising approach to probe the dark matter electromagnetic properties is through the search of photon-mediated dark matter-nucleus interactions in direct

KM3NeT/ORCA is an underwater neutrino telescope under construction in the Mediterranean Sea. Its primary scientific goal is to measure the atmospheric neutrino oscillation parameters and to determine the neutrino mass ordering. ORCA can constrain the oscillation parameters Δm231 and θ23 by reconstructing the arrival direction and energy of multi-GeV neutrinos crossing the Earth. Searches for deviations

We search for a stochastic gravitational-wave background (SGWB) originating from scalar-induced gravitational waves (SIGWs) with the sound speed resonance (SSR) effect using data from Advanced LIGO and Advanced Virgo's first three observing runs. The SSR mechanism, characterized by an oscillating sound speed squared term, can induce a nonperturbative parametric amplification of specific perturbation

We propose a novel gravitational wave production mechanism in the context of quasi-conformal Standard Model extensions, which provide a way to dynamically generate the electroweak scale. In these models, the cosmic thermal history is modified by a substantial period of thermal inflation, potentially supercooling the Universe below the QCD scale. The exit from supercooling is typically realized through

Studies show that the model-independent, fully non-perturbative covariant cosmographic approach is suitable for analyzing the local Universe (z ≲ 0.1). However, accurately characterizing large and inhomogeneous mass distributions requires the fourth-order term in the redshift expansion of the covariant luminosity distance dL(zn). We calculate the covariant snap parameter 𝕊 and its spherical harmonic

The height of the Milky Way diffusion halo, above which cosmic-rays can freely escape the galaxy, is among the most critical, yet poorly known, parameters in cosmic-ray physics. Measurements of radioactive secondaries, such as 10Be or 26Al, which decay equivalently throughout the diffusive volume, are expected to provide the strongest constraints. This has motivated significant observational work to

We investigate a novel scenario involving asymmetric keV-range dark matter (DM) in the form of right-handed (sterile) neutrinos. Based on the Fermi-Dirac distribution, we demonstrate that asymmetric fermionic DM forms a Fermi degenerate gas, making it potentially colder than symmetric fermionic DM. This setup simultaneously accounts for the Universe's baryon asymmetry through tiny Yukawa interactions

We study domain walls (DWs) arising in field theories where Z2-symmetry is spontaneously broken by a scalar expectation value decreasing proportionally to the Universe temperature. The energy density of such melting DWs redshifts sufficiently fast not to overclose the Universe. For the first time, evolution of melting DWs and the resulting gravitational waves (GWs) is investigated numerically using

The observed jet precession period of approximately 11 years for M87* strongly suggests the presence of a supermassive rotating black hole with a tilted accretion disk at the center of the galaxy. By modeling the motion of the tilted accretion disk particle with the spherical orbits around a Kerr-Newman black hole, we study the effect of charge on the observation of the precession period, thereby exploring

With their wide field of view and high duty cycle, water-Cherenkov-based observatories are integral to studying the very high-energy gamma-ray sky. For gamma-ray observations, precise event reconstruction and highly effective background rejection are crucial and have been continuously improving in recent years. In this work, we investigate the application of graph neural networks (GNNs) to background

General Relativity suffers for two main problems which have not yet been overcome: it predicts spacetime singularities and cannot be formulated as a perturbative renormalizable theory. In particular, many attempts have been made for avoiding singularities, such as considering higher order or infinite derivative theories. The price to pay in both cases is to give up locality and therefore they are known

The existence of axions or Axion-Like Particles (ALPs) has been predicted by various Beyond Standard Model (BSM) theories, and the proposed photon-ALP interaction is one of the ways to probe them. Such an interaction will lead to photon-ALP resonant conversion in galaxy clusters, resulting in a polarized spectral distortion in the CMB along the cluster line of sight. The estimation of this signal from

We present exact solutions for the cosmological embedding of a broad class of non-singular black holes and we focus on the behavior of their apparent horizons. The evolution of the latter is analyzed as a function of the cosmological redshift z. We show that its size exceeds that of the event horizon of an isolated black hole and increases monotonically with increasing z. Explicit formulas and numerical

We explore a purely gravitational origin of observed baryon asymmetry and dark matter (DM) abundance from asymmetric Hawking radiation of light primordial black holes (PBH) in presence of a non-zero chemical potential, originating from the space-time curvature. Considering the PBHs are described by a Reissner-Nordström metric, and are produced in a radiation dominated Universe, we show, it is possible

We combine the semi-analytical structure formation model, SASHIMI, which predicts subhalo populations in collisionless, cold dark matter (CDM), with a parametric model that maps CDM halos to self-interacting dark matter (SIDM) halos. The resulting model, SASHIMI-SIDM, generates SIDM subhalo populations down to sub-galactic mass scales, for an arbitrary input cross section, in minutes. We show that

Heavy neutral leptons (HNLs) are constrained by requirements of Big Bang Nucleosynthesis (BBN) as their decays significantly impact the formation of the primordial elements. We propose here a model where the primary decay channel for the HNLs is to an axion-like particle (ALP) and a neutrino. Consequently, HNLs can decay earlier and evade the BBN bound for lower masses, provided the ALPs themselves

Measuring the properties of the intergalactic medium (IGM) and sources during the Epoch of Reionization (EoR) is of immense importance. We explore the prospects of probing the IGM and sources through redshifted 21 cm observations of individual ionized bubbles surrounding known luminous sources during the EoR. Accordingly, we simulate HI 21 cm maps, foreground contaminants, and system noise which are

Obtaining a precise form for the predicted gravitational wave (GW) spectrum from a phase transition is a topic of great relevance for beyond Standard Model (BSM) physicists. Currently, the most sophisticated semi-analytic framework for estimating the dominant contribution to the spectrum is the sound shell model; however, full calculations within this framework can be computationally expensive, especially

Cosmological first-order phase transition (FOPT) sources the stochastic gravitational wave background (SWGB) through bubble collisions, sound waves, and turbulence. So far, most studies on the fluid profile of an expanding bubble are limited to transitions that complete in a much shorter time scale than the cosmic expansion. In this study, we investigate gravitational effects on the fluid profile beyond

The redshifted 21 cm signal of neutral hydrogen can be used as a direct probe of the intergalactic medium during Cosmic Dawn (CD) and Epoch of Reionization (EoR). However, detecting this inherently weak signal has numerous challenges. The major ones include accurate foreground removal from low-frequency radio observations and systematics arising from instrumental effects. The Earth's ionosphere poses

Primordial Black Holes (PBHs) are capable of emitting extremely energetic particles independent of their interactions with the Standard Model. In this work, we investigate whether PBHs evaporating in the early universe could be responsible for some of the observed high-energy neutrinos above the TeV or PeV scale in the present universe. We compute the energy spectrum of neutrinos directly emitted by

We perform a comprehensive analysis of state-of-the-art waveform models, focusing on their predictions concerning kick velocity and inferred gravitational wave memory. Recent advancements in gravitational wave instrumentation have established new benchmarks for the precision of future measurements. To fully exploit the potential of upcoming gravitational wave surveys, it is crucial to concurrently

We study the reionization of the Universe due to haloes that host galaxies undergoing bursts of star formation. By comparing the recent results from the James Webb Space Telescope (JWST) with the cosmological hydrodynamical simulation eagle at z ≥ 6, we find that bursty galaxies have specific star formation rate, sSFR > 10-2 Myr-1, and magnitude, MUV ≤ -17. Most of them reside in haloes of mass ∼ 109

We show for the first time that high-resolution CMB lensing observations can probe structure on sub-galactic scales. In particular, a CMB-HD experiment can probe out to k ∼ 55 h/Mpc, corresponding to halo masses of about 108 M⊙. Over the range 0.005 h/Mpc

We study the generation of high-frequency gravitational waves (GWs) through graviton bremsstrahlung during the decay of inflaton in the post-inflationary universe, focusing on scenarios with a polynomial inflaton potential. Two main reheating channels are considered: decays into bosons (spin 0) and fermions (spin 1/2). We compute the resulting GW spectra from three-body decays, where the inflaton decays

The curvature perturbation in a model of constant-roll (CR) inflation is interpreted in view of the logarithmic duality discovered in ref. [1] according to the δN formalism. We confirm that the critical value β:=φ̈/(Hφ̇)= -3/2 determining whether the CR condition is stable or not is understood as the point at which the dual solutions, i.e., the attractor and non-attractor solutions of the field equation

A key obstacle to accurate models of the first stars and galaxies is the vast range of distance scales that must be considered. While star formation occurs on sub-parsec scales within dark matter (DM) minihalos, it is influenced by large-scale baryon-dark matter streaming velocities (vbc) and Lyman-Werner (LW) radiative feedback which vary significantly on scales of ∼100 Mpc. We present a novel approach

Towards a classification of UV completable Higgs inflation in the framework of parity-even metric-affine gravity, we investigate the particle spectrum of a deformed theory in the large-N limit. In a simple Higgs inflation model in metric-affine gravity, it is known that its UV cutoff is much smaller than the Planck scale. While it calls for UV completion, a concrete example has not yet been found,

Measuring the growth of structure is a powerful probe for studying the dark sector, especially in light of the σ8 tension between primary CMB anisotropy and low-redshift surveys. This paper provides a new measurement of the amplitude of the matter power spectrum, σ8, using galaxy-galaxy and galaxy-CMB lensing power spectra of Dark Energy Spectroscopic Instrument Legacy Imaging Surveys Emission-Line

We study the prospect of the equivalence principle at the quantum regime by investigating the transition probabilities of a two-level atomic detector in different scenarios. In particular, two specific set-ups are considered. (i) Without a boundary: In one scenario the atom is in uniform acceleration and interacting with Minkowski field modes. While in the other the atom is static and in interaction

The SST-1M (webpage: https://sst-1m.space) is a Small-Sized Telescope (SST) designed to provide a cost-effective and high-performance solution for gamma-ray astrophysics, particularly for energies beyond a few TeV. The goal is to integrate this telescope into an array of similar instruments, leveraging its lightweight design, earthquake resistance, and established Davies-Cotton configuration. Additionally

We numerically study the domain walls (DWs) dynamic through 3D lattice simulation, and show that DWs formed by the breaking of a discrete symmetry in the early Universe can be dissipated by a later cosmic first-order phase transition (PT), even if the DWs have entered the scaling regime. The decay speed of the DWs is characterized by the bubble nucleation rate of the first-order PT. The produced gravitational

We discuss a recently proposed fit of the 15-year data set obtained from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) in terms of a relic stochastic background of primordial gravitons, produced in the context of the string cosmology pre-big bang scenario. We show that such interpretation cannot be reconciled with a phenomenologically viable minimal version of such scenario

When light primordial black holes (PBHs) evaporate in the early Universe, they locally reheat the surrounding plasma, creating hot spots with temperatures that can be significantly higher than the average plasma temperature. In this work, we provide a general framework for calculating the probability that a particle interacting with the Standard Model can escape the hot spot. More specifically, we

We perform a systematic study of BBN constraints from photodisintegration for scenarios in which dark-matter annihilations are resonantly-enhanced. To this end, we implement and make available a new class ResonanceModel within an updated version v1.3.0 of ACROPOLIS. While the corresponding implementation is done in a rather model-independent way, we also make available three benchmark models that can

We propose to study a smooth variant of the μ-hybrid inflation model and a non-minimal Higgs model of inflation with quartic non-minimal coupling between the Higgs field and gravity within the context of a realistic GUT gauge group based on supersymmetric SU(4) C × SU(2) L × SU(2) R . These models are incorporated with a realistic scenario of reheating and non-thermal leptogenesis, compatible with

Curl lensing, also known as lensing field-rotation or shear B-modes, is a distinct post-Born observable caused by two lensing deflections at different redshifts (lens-lens coupling). For the Cosmic Microwave Background (CMB), the field-rotation is approximately four orders of magnitude smaller than the CMB lensing convergence. Direct detection is therefore challenging for near-future CMB experiments

Ultralight bosons near rotating black holes can undergo significant growth through superradiant energy extraction, potentially reaching field values close to the Planck scale and transforming black holes into effective transducers for these fields. The interaction between boson fields and fermions may lead to parametric production or Schwinger pair production of fermions, with efficiencies significantly

The upcoming LISA mission will be able to detect gravitational waves from galactic and extragalactic compact binaries. Here, we report on LISA's capability to probe dark matter around these binaries if the latter constitute black holes. By analyzing the variation in the chirp mass of the binary, we show that depending on the black hole masses, LISA should be able to probe their surrounding dark matter

If primordial scalar or tensor perturbations are enhanced on short scales, it may lead to the production of observable gravitational wave signals. These waves may be sourced by scalar-scalar, scalar-tensor or tensor-tensor interactions. Typically, models of inflation capable of producing large peaks in the scalar primordial power spectrum also generate sizeable scalar non-Gaussianity. Previous studies