Primordial black holes (PBHs) with a wide mass distribution imprinted by the thermal history of the Universe, which naturally produces a high peak at the solar mass scale, could explain the gravitational-wave events seen by LIGO/Virgo and up to the totality of the dark matter. We show that compared to monochromatic or log-normal mass functions, the gravitational wave backgrounds (GWBs) from...
High energy cosmic rays reach the solar surface and induce a signal that could be observed in up to five different channels: (i) a cosmic ray shadow (HAWC has measured its energy dependence); (ii) a flux of gamma rays (observed by Fermi-LAT up to 200 GeV); (iii) a flux of high energy neutrons (unfortunately, there are no hadronic calorimeters in space); (iv) a muon shadow (detected by...
As cosmological data have improved, tensions have arisen. One such tension is the difference between the locally measured Hubble constant $H_0$ and the value inferred from the cosmic microwave background (CMB). Interacting radiation has been suggested as a solution, but studies show that conventional models are precluded by high-$\ell$ CMB polarization data. It seems at least plausible that a...
Supernova (SN) explosions are the most powerful cosmic factories of all-flavors, MeV-scale, neutrinos. The presence of a sharp time structure during a first emission phase, the so-called neutronization burst in the electron neutrino flavor time distribution, makes this channel a very powerful one. Large liquid argon underground detectors, like the future Deep Underground Neutrino Experiment...
With the prospect of detecting the cosmological 21 cm signal from the epoch of reionization just over the horizon, methods for extracting maximal cosmological information from this signal are increasingly timely. I will discuss recent work to further develop the effective field theory (EFT) for the 21 cm brightness temperature field during the epoch of reionization, incorporating renormalized...
We derive a closed-form false vacuum decay rate at one loop for a single real scalar field in the thin wall limit. We obtain the bounce solution, together with the Euclidean action, counter-terms and RG running, and we extract the functional determinant via the Gel’fand-Yaglom theorem. Our procedure is valid for a generic spacetime dimension $D$, and we provide an explicit finite renormalized...
Early Universe dynamics beyond the standard single-field slow-roll paradigm may produce a Stochastic Gravitational Wave Background (SGWB) in the LISA band. In this talk, we will present recent advances from the LISA CosWP in creating a 'bank' of templates representing the SGWB produced in popular inflationary models. We adopt a recently developed data analysis pipeline to forecast the...
If primordial black holes (PBHs) contribute more than 10 percent of the dark matter (DM) density, their energy density today is of the same order as that of the baryons. Such a cosmic coincidence might hint at a mutual origin for the formation scenario of PBHs and the baryon asymmetry of the Universe. Baryogenesis can be triggered by a sharp transition of the rolling rate of inflaton with a...
We investigate scalar-tensor theories, motivated by dark energy models, in the strong gravity regime around the black hole at the center of our galaxy. In such theories general relativity is modified since the scalar field couples to matter. We consider the most general conformal and disformal couplings of the scalar field to matter to study the orbital behavior of the nearby stars around the...
Observations of the Lyman-α flux, in overall good agreement with ΛCDM, have long been known to be able to place stringent bounds on models predicting significant small-scale suppressions of the matter power spectrum. Nevertheless, an apparent inconsistency in the determination of the spectrum's tilt at Lyman-α scales has raised the question of whether an overall better fit to the data than...
We for the first time map the range of active-sterile neutrino mixing angles in which leptogenesis is possible in the type I seesaw model with three heavy neutrinos with Majorana masses between 50 MeV and 70 TeV, covering the entire experimentally accessible mass range. Our study includes both, the asymmetry generation during freeze-in (ARS mechanism) and freeze-out (resonant leptotenesis) of...
Axion-photon conversion is a prime mechanism to detect axion-like particles that share a coupling to the photon. We point out that in the vicinity of neutron stars with strong magnetic fields, magnetars, the effective photon mass receives comparable but opposite contributions from free electrons and the radiation field. This leads to an energy-dependent resonance condition for conversion that...
In dense astrophysical environments, the neutrino and antineutrino densities are so extreme that neutrino-neutrino coherent forward scattering leads to collective neutrino oscillations, perhaps affecting the core-collapse mechanism and the nucleosynthesis of elements heavier than iron in compact binary remnants. Due to the profound potential implications for the source’s physics, the so-called...
I will talk about studying the formation of black holes from subhorizon and superhorizon perturbations in a matter dominated universe with 3+1D numerical relativity simulations. We find that there are two primary mechanisms of formation depending on the initial perturbation's mass and geometry -- via direct collapse of the initial overdensity and via post-collapse accretion of the ambient dark...
Dark Matter in our Galaxy may produce a linearly polarized synchrotron signal through the secondary emission of electrons and positrons originating from dark matter annihilations. Using the latest Planck data release, for the first time we use microwave synchrotron polarization to constrain Dark Matter annihilation in the Galaxy. We find that polarization is more constraining than...
When the spontaneous breaking of the Peccei-Quinn (PQ) symmetry occurred, the
resulting angular direction of the PQ field, i.e. the axion could have possessed an initial nonzero velocity arising from additional terms that explicitly break the PQ symmetry. This opens
up the possibility for smaller values of the decay constant than in the conventional scenario.
We elaborate further on the...
The distribution of galaxies provides an ideal laboratory to test deviations from General Relativity. In particular, redshift-space distortions are commonly used to constrain modifications to the Poisson equation, relating the spatial component of the gravitational field with the matter density. However, such constraints rely on the validity of the weak equivalence principle, which has never...
The hitherto unprecedented angular resolution of the Event Horizon Telescope (EHT) has created exciting opportunities in the search for new physics. Recently, the linear polarization of radiation emitted near the supermassive black hole M87* was measured on four separate days, precisely enabling tests of the existence of a dense axion cloud produced by a spinning black hole. The presence of an...
We study the effect of a tangled sub-fG level intergalactic magnetic field (IGMF) on the electrostatic instability of a blazar-induced pair beam. Sufficiently strong IGMF may significantly deflect the TeV pair beams, which would reduce the flux of secondary cascade emission below the observational limits. A similar flux reduction may result from the electrostatic beam-plasma instability, which...
We discuss the micro-physics of cosmic-ray (CR) diffusion as resulting from particle scattering onto the three modes in which the Magneto-Hydro-Dynamics (MHD) cascades are decomposed. Assuming that Alfvén modes are subdominant in confining CRs, due to their anisotropic cascading, we debate over the key points that need to be understood while considering fast-magnetosonic modes as the main...
We study supercooled first order phase transitions which are typical of theories where conformal symmetry is (mainly) spontaneously broken. In these setups the fate of the flat direction parametrically depends on the explicit breaking of conformal symmetry. This need to be in a particular region to realize a supercooled first order phase transition. We identify the ``supercooling window'' in...
