The distribution of baryons in the cosmic web contains a wealth of cosmological and astrophysical information. In particular, measurements of the hot gas in anisotropic structures—such as filaments and superclusters—are important for the census of cosmic baryons. Such localized anisotropic measures can also provide cosmological information beyond two-point statistics and help to constrain...
Precise measurements at small angles of the cosmic microwave background (CMB) angular power spectrum (APS), done by the Planck collaboration, have stimulated accurate analyses of the lensing amplitude parameter $A_L$ to confirm if it satisfies the value expected by the flat $\Lambda$CDM concordance model, i.e. $A_L = 1$.
We discuss a possible excess in the Planck APS not accounted by the...
We present a fully differential, field level emulator for large-scale structure formation that is accurate in the deeply nonlinear regime. Our emulator consists of two convolutional neural networks trained to output the nonlinear displacements and velocities of N-body simulation particles based on their linear inputs. Cosmology dependence is encoded in the form of style parameters at each...
A new and promising technique for observing the Universe and study the dark sector is the intensity mapping of the redshifted 21-cm line of neutral hydrogen (HI). The Baryon Acoustic Oscillations [BAO] from Integrated Neutral Gas Observations (BINGO) radio telescope will use the 21-cm line to map the Universe in the redshift range $0.127 \le z \le 0.449$, in a tomographic approach, with the...
Covariance matrices are a fundamental component in the process of constraining physical models from observations, determining the sensibility of the dataset to modifications in the model parameters. However, estimating them correctly presents many challenges; in particular, when computing this quantity using simulations, one must assume a galaxy formation model and a set of fiducial...
We re-examine sterile neutrino dark matter in gauged $U(1)_{B-L}$ model. Improvements have been made by proper inclusion of all relevant processes and tracing the evolution of the number densities of sterile neutrino and extra neutral gauge boson $Z'$. The energy density of $Z'$ turns out to to be much greater than in earlier studies. We revise the space of the viable parameters .
We present a finite temperature model for dark matter. In this work, we show coupled equations for self-interacting scalar dark matter which can include both a condensed, low momentum fuzzy component and one with higher momenta that may be described as a collection of classical particles. We do this from first principles, using two distinct but equivalent approaches: firstly via the...
Gravitational production of massive particles due to cosmic expansion can be significant during the inflationary and reheating period of the Universe. In this work, we focus on the gravitational production of light vector bosons that couple feebly to the Standard Model (SM) particles. Due to the very feeble coupling, the light vector bosons never reach thermal equilibrium and if the Hubble...
A prediction of the standard LCDM cosmological model is that dark matter (DM) halos are teeming with numerous self-bound substructure, or subhalos. The most massive ones host the observed dwarf satellite galaxies, while smaller subhalos may host no stars/gas at all and thus may have no visible astrophysical counterparts and would remain completely dark. Yet, some of these ‘dark satellites’ are...
Phase correlations have been proposed as an efficient higher-order statistic able to extract cosmological and astrophysical information that is largely independent from the two-point function or power spectrum. In this talk, we develop an estimator for the line correlation function of projected fields, corresponding to the correlation between the harmonic-space phases of the field at three...
I will describe recent developments on the nonlinear modelling of LSS, in the context of momentum-exchange interacting dark energy. I will review the Dark Scattering model and show how it can alleviate the current $S_8$ tension between early and late-Universe data. I will present new constraints on this interaction from a likelihood analysis of the BOSS DR12 power spectrum multipoles, while...
In this talk, I will present a method to extract the Scalar Vector Tensor (SVT) first order perturbations from the Cosmological Perturbations Theory developed in a homogeneous and isotropic Geodesic Light Cone (GLC) background. Due to its adapted light-cone decomposition, the GLC-SVT relation becomes involved, notwithstanding, I will present two different strategies to easy this relation. In...
Axionlike particles (ALPs) are among the most well-motivated extensions of the Standard Model of particle physics, and are increasingly popular dark matter candidates. Extreme astrophysical environments, such as dense and hot supernovae, or vast and magnetised galaxy clusters, provide unique opportunities to test the theory. In this talk, I will discuss recent progress in searching for ALPs...
Axions are often accompanied by discrete symmetries that are
spontaneously broken in the early universe and lead to the formation of
a network of cosmic domain walls (DW).
In this talk, I will discuss the stochastic gravitational wave (GW)
background produced by such networks. I will show that in some heavy QCD
axion models, the GW signal is within reach of current and future
detectors...
We study axion dark matter production from a misalignment mechanism in scenarios featuring a general nonstandard cosmology. Before the onset of Big Bang nucleosynthesis, the energy density of the universe is dominated by a particle field $\phi$ described by a general equation of state $\omega$. The ensuing enhancement of the Hubble expansion rate decreases the temperature at which axions start...
Stars whose initial mass is between approximately 150 and 240 M$_\odot$ face a fate of complete explosion in a pair instability supernova (PISN). However, by injecting energy into the star, it may be possible in some cases to avoid this fate. We outline conditions on this energy injection which can lead to the survival or incomplete explosion of the star, and we discuss how dark matter...
Gravitational-wave interferometers can be used to probe the existence of dark matter. Different types of dark matter, such as primordial black holes, ultralight boson clouds around spinning black holes, axions and dark photons, could leave different imprints on gravitational-wave detectors. While arising from physically different sources, such gravitational-wave and dark-matter signals share...
Future generations of galaxy redshift surveys will sample the large-scale structure of the Universe over unprecedented volumes with high-density tracers, allowing for precise measurements of the clustering statistics. In order to properly exploit the full potential of such data, a robust likelihood pipeline is required, starting with an accurate theoretical prediction of cosmological...
We study the spherical collapse of non-top-hat matter fluctuations in the presence of dark energy with arbitrary sound speed ($c_s$). The model is described by a system of partial differential equations solved using a pseudo-spectral method with collocation points. This method can reproduce the known analytical solutions in the linear regime with an accuracy better than $10^{-6}$ % and better...
General Relativity (GR) has been successfully tested mainly at Solar system scales; however, in the last few decades, galaxy-scale tests have become popular. In particular, some recent works dedicate close attention to the $\eta_{\text{PPN}}$ parameter, which is commonly associated with the spatial curvature generated per unit mass. Under the assumption of GR, and a vanish anisotropic stress...
In this talk I will present the formulation of the Effective Field Theory (EFT) of black hole perturbations within scalar-tensor theories on an inhomogeneous background. In particular, the EFT is constructed while keeping a background of a scalar field to be timelike, which spontaneously breaks the time diffeomorphism. I will then discuss a set of consistency relations that are imposed by the...
I will introduce a fast and complementary approach to study galaxy rotation curves directly from the sample data, instead of first performing individual rotation curve fits. The method is based on a dimensionless difference between the observational rotation curve and the expected one from the baryonic matter ($\delta V^2$). It is named as Normalized Additional Velocity (NAV). Using 153...
Superconducting nanowires, a mature technology originally developed for quantum sensing, can be used as a target and sensor with which to search for dark matter interactions with electrons. We leverage recent developments in the theory of dark matter interactions in dielectrics to robustly predict the event rate in a nanowire device, fully accounting for the many-body physics of the detector....
The Euclid space-based survey will observe and map the distribution of galaxies with unprecedented accuracy, allowing us to improve the knowledge of the Universe and its dynamics as well as the nature of the so-called dark matter that contributes up to a quarter of the total energy density of the Universe. Furthermore, key research will involve the measurements of the subtle features produced...
The evidence for dark matter is overwhelming, yet there has not been an unambiguous detection of a dark matter particle. The XENON collaboration has operated successively larger experiments in the hunt for WIMP-dark matter using dual phase time projection chambers with xenon as the target material. The XENON collaboration is one of the leading collaborations in constraining the WIMP-nucleon...
A kinetic coupling between the photon and a dark photon, a massless U(1)-gauge boson in the dark sector, transfers dark photon’s birefringence to observed cosmic birefringence. Regardless of the origin of the dark birefringence, the amplitude and unique frequency-dependence of the cosmic birefringence depend on the kinetic-coupling constant and the dark-photon temperature. To explain the...
Primordial Black Holes (PBHs), first postulated more than half a century ago, remain an active and fascinating area of research and provide an exciting prospect for accounting for Dark Matter. In this talk I will discuss the possibilities for production of PBHs near to Dark Matter mass scales from realistic multi-field inflation models that arise naturally from supergravity. These models fit...
Through their observable properties, the first and smallest dark matter halos represent a rare probe of subkiloparsec-scale variations in the density of the early Universe. These density variations could hold clues to the nature of inflation, the postinflationary cosmic history, and the identity of dark matter. The first halos are understood to possess a uniquely compact central mass...
The production of dark relics from the decay of the primordial inflaton condensate must always be considered when building models of the very early Universe. Even in the absence of direct couplings, dark matter and radiation can be produced from the gravitational interaction between the dark and inflaton sectors. In this talk I will discuss the non-equilibrated production of scalar dark matter...
We discuss compact stars consisting of cold quark matter and fermionic dark matter treated as two admixed fluids. After the computation of the stellar structure and fundamental radial oscillation frequencies for different masses of the dark fermion in the cases of weak and strong self-interacting dark matter, we show that the fundamental frequency can be dramatically modified and, in some...
We address the issue of black hole scalarization and its compatibility with cosmic inflation and big bang cosmology from an effective field theory (EFT) point of view. In practice, using a well-defined and healthy toy model which (in part) has been broadly considered in the literature, we consider how higher-order theories of gravity, up to cubic operators in Riemann curvature, fit within this...
The detection of non-Gaussianity in primordial perturbations offers monumental new information about the early Universe. All models of inflation predict at least some level of primordial non-Gaussianity, and many models result in potentially observable non-Gaussian signatures. While detection efforts thus far have not found any significant primordial non-Gaussianity, they are not sensitive to...
In order to prepare for the upcoming wide-field cosmological surveys, large simulations of the
Universe with realistic galaxy populations are required. In particular, the tendency of galaxies
to naturally align towards overdensities, an effect called intrinsic alignments (IA), can be a
major source of systematics in the weak lensing analysis. As the details of galaxy formation
and...
All models of inflation predict some non-Gaussian signatures in the cosmological distribution of energy, the search for which is a subject of great importance to our understanding of the early universe. In this work, we present simulated sky maps for a novel extended stochastic inflation model that is motivated by an ambitious suite of high-accuracy lattice simulations of early-universe field...
The fundamental nature of dark matter so far eludes direct detection experiments, but it has left its imprint in the large-scale structure (LSS) of the Universe. Extracting this information requires accurate modelling of structure formation and careful handling of astrophysical uncertainties. I will present new bounds using the LSS on two compelling dark matter scenarios that are otherwise...
Since the late 1980s, when the first gravitational arcs were observed, the strong effect of gravitational lensing has been a key observable in both Cosmology and Extragalactic Astrophysics. This phenomenon predicted by General Relativity, whose effect is the distortion and magnification of the image of a distant cosmic object (source) due to the deflection of the light’s trajectory caused by...
