To test the vast number of modified gravity models, a systematic and comprehensive approach is necessary when analysing the data from cosmological surveys. The novel observable \hat{J}, capturing the evolution of the combined gravitational potential Ψ + Φ, provides a powerful and model-independent test of gravity. Recently, we have performed the first measurement of this observable from Dark...
In this work we present our pipeline for a joint analysis at the angular power spectrum level between measurements of galaxy positions from Dark Energy Survey Years 3 data release (DES Y3) and CMB lensing from the Atacama Cosmology Telescope Year 6 data release (ACT DR6) on a common area of around $4000\ \rm{deg}^2$. We show preliminary results, including several null-tests and inference on...
In this talk, we will review what peculiar velocities are and how they can help us in better understanding both our local universe, its cosmological components and also studying relativistic effects. In particular, we will focus on the information we can extrapolate from the Pantheon+SH0ES and CosmicFlow4 datasets.
Combining measurements of the growth rate of cosmic structures with gravitational lensing is considered as the optimal way to test for deviations from General Relativity on cosmological scales. In my talk, I will demonstrate that this standard method suffers from an important limitation, since models of dark matter with additional interactions can lead to exactly the same signatures as...
We present a full methodology for analyzing galaxy clustering on the lightcone with the 2-point correlation in the Spherical Fourier-Bessel (SFB) formalism. SFB is a natural choice to account for all wide-angle and relativistic (GR) effects, allowing to efficiently extract information from large volume galaxy surveys.
We extend previous studies using SFB by including all projection and GR...
We determine the solar neutrino fluxes from the global analysis of the most up-to-date terrestrial and solar neutrino data including the final results of the three phases of Borexino. The analysis are performed in the framework of three-neutrino mixing with and without accounting for the solar luminosity constraint. We discuss the independence of the results on the input from the Gallium...
Hot white dwarfs lose energy mainly in the form of neutrinos through plasmon decay from the inner part of the star. BSM physics can have visible contributions to the cooling of these compact objects. The aim of this study is to show how hot white dwarf cooling could be altered by a dark photon from the L_mu - L_tau model and explore these effects from ultra-light to heavy intermediators. This...
Cosmic rays can be probed via direct detection at the Earth’s position or indirectly through diffuse emissions of gamma-rays and neutrinos produced by the interaction of cosmic rays with the interstellar medium in other parts of the Galaxy. It is commonly assumed in the modelling of galactic cosmic rays that the source density is smooth and steady. However, supernova remnants, the likely...
We investigate IceCube's ability to constrain the neutrino relic abundance using events from the recently identified neutrino source NGC1068. Since these neutrinos have large energies $\gtrsim$ 1 TeV and have propagated through large distances, they make a great probe for overabundances of the cosmic neutrino background.
The propagation of neutrinos from NGC1068 was simulated by solving a...
Magnetic monopoles are intriguing hypothetical particles and inevitable predictions of Theories of Grand Unification. They are produced during phase transitions in the early universe, but mechanisms like the Schwinger effect in strong magnetic fields could also contribute to the monopole number density. I will show how from the detection of intergalactic magnetic fields we can infer additional...
Understanding the conditions conducive to particle acceleration at collisionless, non-relativistic shocks is important for the origin of cosmic rays. We use hybrid (kinetic ions—fluid electrons) kinetic simulations to investigate particle acceleration and magnetic field amplification at non-relativistic, weakly magnetized, quasi-perpendicular shocks. So far, no self-consistent kinetic...
A possible way to generate primordial black holes as candidates for the entirety of dark matter is a large power spectrum of inflationary curvature fluctuations. Recently, questions have been raised regarding the validity of perturbation theory in this context. We compute the one-loop power spectrum in ultra-slow roll inflation, including all relevant interactions for such analysis, along with...
Nowadays, the search for primordial gravitational waves is mainly focused on the parity-odd polarization pattern in the CMB - the B-modes. A correct interpretation of B-mode measurements strongly relies on understanding their production mechanism. One intriguing scenario is gravitational waves generation by gauge fields. The tachyonic amplification of the gauge fields modes during inflation...
Fundamental scale invariance has been proposed as a new theoretical principle beyond renormalizability. Besides its highly predictive power, a scale-invariant formulation of gravity could provide a natural explanation for the long-standing hierarchy problem and interesting applications in cosmology.
We present a globally scale-invariant model of quadratic gravity and study its solutions in a...
Slow first-order phase transitions generate large inhomogeneities that can lead to the formation of primordial black holes (PBHs). We show that the gravitational wave (GW) spectrum then consists of a primary component sourced by bubble collisions and a secondary one induced by large perturbations. The latter gives the dominant peak if $\beta/H_0 < 10$, impacting, in particular, the...
In standard leptogenesis models, the baryon asymmetry is initially produced as a lepton asymmetry via the out of equilibrium decays of the lightest right handed neutrino (RHN).
There are however constraints on the RHN mass that are in tension; the naturalness constraint on the Higgs mass from RHN loop corrections, i.e. the Vissani bound, puts a limit on the RHN mass which is lower than is...
We introduce a novel approach to investigate sectors solely gravitationally coupled, characterized by significant anisotropies. These anisotropies undergo damping through gravitational interactions with the baryon-photon fluid, inducing heating in the process. The resultant injected heat leads to observable distortions in the cosmic microwave background spectrum. We provide analytic estimates...
We present updated constraints on 'light' Dark Matter (DM) particles with masses between 1 MeV and 5 GeV. In this range, we can expect DM-produced pairs to upscatter low-energy ambient photons in the Milky Way via the Inverse Compton process, and produce a flux of X-rays that can be probed by a range of space observatories. Using diffuse X-ray data from XMM-Newton and realistic cosmic-ray...
Sub-GeV dark matter (DM) has been gaining significant interest in recent years, since it can account for the thermal relic abundance while evading nuclear recoil direct detection constraints. However, sub-GeV DM is still subject to a number of constraints from laboratory experiments, and from astrophysical and cosmological observations. In this work, we compare these observations with the...
In the high mass range, primordial black holes are constrained by the observed velocity dispersion of the Galactic disk, as they are expected to heat up stars through two-body encounters. These constraints have been obtained assuming that the PBHs are smoothly distributed in the DM halo. However, PBHs are expected to form bound structures under the effect of gravity; furthermore, it has been...
Sterile neutrinos represent a minimal and well motivated extension of the Standard Model (SM). For masses at the keV scale, their mixing to the active neutrinos offers a minimal explanation of the dark matter (DM) density. The very same mixing inevitably leads to radiative photon emission and the non-observation of such peaked X-ray lines virtually rules out this minimal sterile neutrino DM...
Primordial black holes (PBHs) are currently in the spotlight as they may solve several open questions in astrophysics and cosmology.
We describe an exact formalism for the computation of the abundance of PBHs in the presence of local non-gaussianity (NG).
Then, we describe the phenomenological relevance of our results for the connection between the abundance of PBHs and the
stochastic...
High-Frequency Gravitational Waves (HFGWs) constitute a unique window on the early Universe as well as exotic astrophysical objects. If the current gravitational wave experiments are more dedicated to the low frequency regime, the graviton conversion into photons in a strong magnetic field constitutes a powerful tool to probe HFGWs. In this paper, we show that neutron stars, due to their...
It is well known that clouds of ultralight particles surrounding black holes produced by the superradiant instability can experience Landau-Zehner transitions if the black hole is part of a binary system.
We study the effect of orbital eccentricity, backreaction of the cloud onto it and observational possibilities with future gravitational-wave detectors like the Laser Interferometer Space...
The electroweak phase transition is a promising explanation for the origin of baryon asymmetry in the universe, a core problem in cosmology and particle physics.
An extension of the Standard Model is necessary to generate a strong first-order phase transition. Besides representing a target for several future-generation colliders, such Beyond the Standard Model (BSM) theories can generate -...
It is well known that spontaneous breaking of discrete symmetries produce topological objects called domain walls, which must decay in order not to dominate the energy density of the universe. One of the possible decay scenarios is nucleating holes bounded by cosmic strings on the walls. Once they are nucleated, the holes expand faster and faster by eating the energy of the domain walls and...
We consider a model, where a single inflaton interacts as an axion with Yang-Mills gauge bosons. As these rapidly thermalize, the friction felt by the inflaton field is increased, leading to a self-amplifying process. The corresponding gravitational wave spectrum is enhanced by thermal contributions at large confinement scales of the Yang-Mills sector, which heats up to high temperatures, yet...
We present a special property of natural polynomials related to the overtone label of quasi-normal modes for Schwarzschild black holes. The natural polynomials for the radial Teukolsky equation have been the subject of recent work involving quasinormal modes of Kerr black holes. These polynomials, which can be constructed using Gram-Schmidt orthogonalization, are a basis for the ringdown...
We study the quadratic quasi-normal modes of a Schwarzschild black hole, i.e. those perturbations that originate from the coupling of two (linear) quasi-normal modes.
Assuming the amplitude of the two linear modes is known, we compute the amplitude of the resulting quadratic mode for a wide range of possible angular momenta. Finally, we reconstruct the waveform in radiation gauge.
For a quantitative investigation on the time evolution of heavy thermal dark matter at and after thermal freeze-out, near-threshold processes need to be taken into account which have a large impact on the observed dark matter relic abundance. We study the recoil effect of heavy dark matter pairs in a thermal bath and compute the thermal rates of dark matter fermion-antifermion pairs in the...
Faced with the lack of observational evidence supporting the existence of new physics at the electroweak scale, alongside overwhelming experimental evidence that hints at the need for the exploration of new phenomena, such as neutrino masses/mixing or dark matter, new approaches to beyond the Standard Model (SM) phenomenology become imperative. Gravitational waves stemming from first-order...
Weakly interacting massive particles (WIMPs) are by far the most extensively studied class of CDM as the correct dark matter abundance is easily reproduced with cross sections around the weak scale. They have been extensively searched for by many experiments (direct and indirect detection, and colliders) with no success. The null results reported thus far motivate us to explore alternative...
Gravitational particle production of spectator fields due to the expansion universe during the inflationary and reheating phases of the early universe is of particular interest in the context of dark matter, since it allows to constrain the properties of the dark candidate
by comparing the density of particles produced with the observed dark matter abundance. In such processes, tachyonic...
Axions and axion-like particles (ALPs) have gained attention as potential dark matter candidates, leading to extensive research into their detection and characterization. Energy density fluctuations in the ALP field can result in the formation of axion miniclusters (AMC), gravitationally bound configurations with implications for dark matter structure. While widely accepted in the...
A strongly self-interacting component of dark matter can lead to formation of compact objects. These objects (dark stars) can in principle be detected by emission of gravitational waves from coalescence with black holes or other neutron stars or via gravitational lensing. However, in the case where dark matter admits annihilations, these compact dark matter made objects can have significant...
We investigate how the primordial power spectrum on small scales could be constrained using 21cm line intensity mapping in the dark ages. The focus is on models that imprint an increase of the matter spectrum at large angular multipoles.
We study a few specific models, including early matter domination, primordial black holes and vector dark matter, and then parameterize small scale features...
We discuss a class of effective extensions of the SU(2) Georgi–Glashow model and discuss its Bogomol’nyi–Prasad–Sommerfield (BPS) limit. We identify a specific subclass of these models that admit analytical solutions of the monopole type. We present some concrete examples and find that the resulting monopoles tend to have their energy concentrated not in their center, but rather in a spherical...
Shock waves driven by merger events can continuously source self-generated magnetic fields at the periphery of galaxy clusters. Diffuse non-thermal emission and polarization measurements from radio relics indicate a magnetisation of the intracluster medium due to merger shocks in addition to particle acceleration at the shock site. I will outline the growth and saturation of such magnetic...
We propose a novel non-thermal realisation for leptogenesis that relies on the out-of-equilibrium decay of an axion-like particle (ALP) into right-handed Majorana neutrinos (RHN) in the Early Universe, and that it opens the parameter space of successful leptogenesis down to TeV-scale RHNs, with values of $f_a > 10^{11}$ GeV and $m_a > 10^{4}$ GeV for the ALP decay constant and mass.
We also...
Slow first-order phase transitions generate large inhomogeneities that can lead to the formation of primordial black holes (PBHs). We show that the gravitational wave (GW) spectrum then consists of a primary component sourced by bubble collisions and a secondary one induced by large perturbations. The latter gives the dominant peak if $\beta/H_0 < 10$, impacting, in particular, the...
In this talk, I will address the issue of the strong backreaction regime in the abelian axion inflation scenario, extending results from 2303.17436 and ongoing work. I will do a revision of the mild and strong backreaction regimes, during and at the end of inflation, and also show how they can be distinguished in terms of dynamics and lengthening of the inflationary period, as well as, the...
Combining measurements of the growth rate of cosmic structures with gravitational lensing is considered as the optimal way to test for deviations from General Relativity on cosmological scales. In my talk, I will demonstrate that this standard method suffers from an important limitation, since models of dark matter with additional interactions can lead to exactly the same signatures as...
In standard leptogenesis models, the baryon asymmetry is initially produced as a lepton asymmetry via the out of equilibrium decays of the lightest right handed neutrino (RHN).
There are however constraints on the RHN mass that are in tension; the naturalness constraint on the Higgs mass from RHN loop corrections, i.e. the Vissani bound, puts a limit on the RHN mass which is lower than is...
Different thermal resummation techniques impact the gravitational wave (GW) spectra from cosmological first-order phase transitions predicted in a given particle physics model. To investigate this effect, we perform large-scale parameter scans of the electroweak phase transition (EWPT) in the dynamical real-singlet extension of the Standard Model (SM) using three different perturbative...
In this contribution we investigate the viability of leptogenesis in the superweak extension of the standard model. We focus on the parameter space of the model with relatively light sterile neutrinos with masses comparable to the electroweak scale and a new singlet scalar that is heavier than the Higgs boson. We present a comprehensible analysis of leptogenesis within the model with...
Magnetic monopoles are intriguing hypothetical particles and inevitable predictions of Theories of Grand Unification. They are produced during phase transitions in the early universe, but mechanisms like the Schwinger effect in strong magnetic fields could also contribute to the monopole number density. I will show how from the detection of intergalactic magnetic fields we can infer additional...
The non-Gaussian tail of the PDF of primordial scalar perturbations is a key element to determine the abundance of primordial black holes. These primordial non-Gaussianities arise, at least partly, from the non-linear, super-horizon dynamics of inflationary perturbations. Such non-linearities have been computed by combining classical non-linear techniques (the $\delta N$ formalism) with the...
A possible way to generate primordial black holes as candidates for the entirety of dark matter is a large power spectrum of inflationary curvature fluctuations. Recently, questions have been raised regarding the validity of perturbation theory in this context. We compute the one-loop power spectrum in ultra-slow roll inflation, including all relevant interactions for such analysis, along with...
We consider a model, where a single inflaton interacts as an axion with Yang-Mills gauge bosons. As these rapidly thermalize, the friction felt by the inflaton field is increased, leading to a self-amplifying process. The corresponding gravitational wave spectrum is enhanced by thermal contributions at large confinement scales of the Yang-Mills sector, which heats up to high temperatures, yet...
Different models of inflationary magnetogenesis have been receiving a lot of attention in the literature for the last two decades providing a possible explanation for the large-scale magnetic fields in voids, seeds for the astrophysical magnetic fields and having relation to baryogenesis, dark matter production, cosmological Schwinger effect etc. However, the presence of gauge fields during...
Fundamental scale invariance has been proposed as a new theoretical principle beyond renormalizability. Besides its highly predictive power, a scale-invariant formulation of gravity could provide a natural explanation for the long-standing hierarchy problem and interesting applications in cosmology.
We present a globally scale-invariant model of quadratic gravity and study its solutions in a...
It is well known that clouds of ultralight particles surrounding black holes produced by the superradiant instability can experience Landau-Zehner transitions if the black hole is part of a binary system.
We study the effect of orbital eccentricity, backreaction of the cloud onto it and observational possibilities with future gravitational-wave detectors like the Laser Interferometer Space...
Sub-GeV dark matter (DM) has been gaining significant interest in recent years, since it can account for the thermal relic abundance while evading nuclear recoil direct detection constraints. Such light DM must carry a larger energy to be probed, either directly or through missing energy/momentum, making beam dump and fixed target experiments ideal for this mass range. Here, we extend the...
We present updated constraints on 'light' Dark Matter (DM) particles with masses between 1 MeV and 5 GeV. In this range, we can expect DM-produced pairs to upscatter low-energy ambient photons in the Milky Way via the Inverse Compton process, and produce a flux of X-rays that can be probed by a range of space observatories. Using diffuse X-ray data from XMM-Newton and realistic cosmic-ray...
One long-standing tension in the determination of neutrino parameters is the mismatched value of the solar mass square difference, $\Delta m^2_{21}$, measured by different experiments: the reactor antineutrino experiment KamLAND finds a best fit larger than the one obtained with solar neutrino data. Even if the current tension is mild ($\sim 1.5\sigma$), it is timely to explore if independent...
The abundance of primordial black holes is constrained by observations of the Cosmic Microwave Background (CMB): these compact objects would accrete matter and emit high-energy photons, altering the statistical properties of the CMB. The presence of dense dark matter mini-halos around the PBHs has been used to further tighten the bounds, as these would boost the accretion rates. In this...
