We propose a new solution to explain the anomalous absorption feature detected by the EDGES collaboration in the 50-100 MHz range, using a new millicharged dark matter model, taking into account the existing cosmological and astrophysical constraints. We predict new unique signals to test our dark matter model with future cosmological surveys.
Microlensing of extragalactic sources, in particular the probability of significant amplifications, is a potentially powerful probe of the abundance of compact objects outside the halo of the Milky Way. Accurate experimental constraints require an equally accurate theoretical model for the amplification statistics produced by such a population. In this article, we argue that the simplest...
I present a fully Bayesian MCMC-based signal extraction technique, which also solves the E/B-leakage problem for Stage-IV Surveys caused by their partial sky coverage. For cosmic shear, classical analyses lose information cutting off small scales because the noise dominates its signal, and additionally large scales as a result of the leakage between E and B modes. Our code Almanac allows us to...
The big open questions we still have currently in the fields of gravitation and cosmology, such as the dark matter and dark energy problems, among other reasons, have led to the development of many modified theories of gravity. These theories need to be tested in various scenarios to see whether they solve the problems they try to solve. Neutron stars are one of the best astrophysical...
In the late 90’s, Reiss et al. [1] and Perlmutter at al. [2] by taking the Supernovae 1a independently proved that the universe is passing through an accelerated expansion. Many observations have supported this accelerated expansion of the late time universe [1,2,3,4,5]. The biggest mystery in the early universe is the production of excess of matter over antimatter [6,7,8. The present study...
Neural nets have become popular to accelerate parameter inferences, especially for the upcoming generation of galaxy surveys in cosmology. As neural nets are approximative by nature, a recurrent question has been how to propagate the neural net’s approximation error, in order to avoid biases in the parameter inference. We present a Bayesian solution to propagating a neural net’s approximation...
In the framework of the Brans-Dicke scalar-tensor theory of gravitation, we investigate the role of a self-interacting fermionic field in an FLRW universe filled with dust and radiation constituents. This model is shown to present a variety of qualitative behaviors, depending on the numerical parameters chosen. In particular, we find that the fermionic field is capable of promoting a...
Intrinsic alignment (IA) modelling and photometric redshift estimation are two of the main sources of systematic uncertainty in weak lensing surveys. We investigate the impact of redshift errors when using different IA models. We show that both errors on the mean of the redshift bin $\delta_z$ and errors of the width of the redshift bin $\sigma_z$ can lead to biases in cosmological...
As numerical complexities of cosmological models are increasing in recent years, so too are the demands for resources when computing solutions to the Einstein-Boltzmann equations with codes like \textsc{class} and \textsc{camb}. A solution to this demand is, of course, more computational power through increasingly better and faster hardware, but perhaps another and more sustainable approach is...
It has been shown in the literature that detections of gravitational waves (GWs) emitted by binary sources can provide measurements of luminosity distance. The events followed by electromagnetic counterparts are, then, suitable for probing the distance-redshift relation and doing cosmological parameter estimation, as well as investigating modified gravity models. In the context of the...
We studied the four models implemented in PYTHIA8 for the production of dark matter or associated particles at the LHC based on the simplest extensions of the Standard Model. The first model includes dark matter production via s-channel mediators. This includes production in association with a jet for a vector boson or scalar mediator. Aside from the standard simplified models where the dark...
Primordial black hole (PBH) has come up as a very promising cold dark matter candidate in recent years. The signature of PBHs in the gravitational wave background is expected as PBH formation requires a large amplfication in inflationary scalar curvature perturbation, which sources the tensor perturbation in second-order and leads to a detectable amplification in the gravitational wave (GW)...
We consider an extension of the novel 4D Einstein-Gauss-Bonnet (EGB) gravity by proposing a coupling between the scalar field and the Gauss-Bonnet term, which is otherwise absent in the novel 4D EGB theory, and demonstrate that the additional contributions to the equations of motion come from both the scaling of a coupling constant and the non-minimal coupling between the scalar field and...
Several physical systems of interest in cosmology, such as the Lovelock extension of general relativity in higher dimensions, k-essence fields, Horndeski theories, and nonlinear electrodynamics, have apparent ill-defined sympletic structures, due to the fact that their Hamiltonians are multivalued functions of the momenta. In this talk, based on the paper [PRD 105, 084064 (2022)], the...
We consider a minimally massless coupled quantum scalar field with an asymmetric (quartic plus cubic) self interaction, V (φ) = λφ^4/4!+βφ^3/3! in the (3 + 1)-dimensional inflationary de Sitter background. This potential is bounded from below regardless the sign of β. The motivation of this study comes from the fact that such a potential may generate negative vacuum expectation value of V(φ)...
Early dark energy (EDE) alleviates the H_0 tension at the cost of increasing the clustering amplitude and worsening the $S_8$ discrepancy. Motivated by massive neutrinos' ability to suppress structure, we study their impact on EDE combining Planck and BOSS full-shape clustering data. A Bayesian analysis returns no evidence for a non-zero neutrino mass sum $M_{\nu}$ ($<0.15,{\rm eV}$ at...
Demanding the validity of the Generalized Second Law implies the existence of entropy bounds. By considering the absorption of matter from arbitrarily close to the horizon, Bekenstein and collaborators derived a universal entropy bound valid for any charged, rotating distribution of matter (including the Kerr-Newman black hole); and, based on the no-hair conjecture, argued that this bound...
In this talk I will show how the Expansion Lensing relationship d_L=d_A(1+z) is derived from the Friedmann-Lemaître-Robertson-Walker (FLRW) metric. The expression also follows from the fact that the angular distance of a galaxy (d_A=S/theta), i.e. the distance at emission, is defined identically for both static and expanding universes, and hence both images subtend the same angle theta....
By choosing a suitable set of cosmological parameters, one can classify them into two groups with respect to their impact on the linear matter power spectrum $P_\mathrm{L}(k)$ when it is expressed in Mpc units: the evolution parameters, $\Theta_\mathrm{e}$, which determine its amplitude at a given redshift and the shape parameters, $\Theta_\mathrm{s}$, which only affect its shape. This...
Fast Radio Bursts (FRBs) are a relatively recent discovered object in cosmology and astrophysics, whose origin is still an open problem. They are a class of brief ($\sim$ ms) and bright ($\sim$ Jy) radio transients that have been detected by a number of radio telescopes around the globe. There is a new generation of radio telescopes coming online, such as the BINGO, CHIME, SKA and others,...
At scales of dozens of Mpcs, the galaxy distribution forms the cosmic web. Galaxy clusters occupy its nodes and are connected to other nodes by vast filamentary chains of galaxies and groups of galaxies. In this work we are investigating some nearby superclusters and filaments in the southern skies. We use the high-precision photometric redshifts obtained in the 12 band S-PLUS photometric...
In this work, we generalize to a viable Horndeski theory of gravity, the most general scalar-tensor theory that has second-order field equations in four dimensions, the expression of a statistically homogeneous and unpolarized stochastic gravitational wave background signal measured as the correlation between the individual signals detected by two not coincident and not coaligned GW...
Astrochemistry plays an important role in the most of astrophysical processes on all stages of the universe life. Unfortunately, the most of the chemical processes can't be simulated in labs because of the physical conditions. We will show our latest high-performance computing code for numerical simulation of astrochemical problems. This code can be used as standalone application for...
The well-known small-scale discrepancies between the observed satellite abundance in the Local Group and predictions from Cosmological simulations in CDM seems to point to missing physics in our models. This new physics may be a different dark matter nature beyond the standard WIMP candidate. In my talk I will discuss how the internal structure and increasing discoveries of fainter galaxies...
We present a joint analysis of the power spectra of the Planck Compton y-parameter map and the projected galaxy density field using the WISE all-sky survey. We detect the statistical correlation between WISE and Planck data (gy) with a significance of 21.8σ. We also measure the auto-correlation spectrum for the tSZ (yy) and the galaxy density field maps (gg) with a significance of 150σ and...
Magnetic fields present in the Universe and interactions with the cosmic radiation backgrounds play an important role shaping the flux of the ultrahigh energy cosmic rays. To account for both processes we include in the SimProp cosmic ray propagation code a routine to follow the direction of propagation of the particles in a turbulent magnetic field. We compute thus the modification of the...
We study the tunneling probability of a massive ($m_w$) uncharged scalar packet out from a near-extremal, static charged black hole (with mass $M$ and charge $Q \to M^+$). We show that there is indeed a \textit{net} probability that a massive uncharged particle tunnels out from the black hole so that the final state (with new mass $M'\equiv M-m_w < Q$) does violate the cosmic censorship...
Oscillons are oscillating, localized configurations in real scalar field theories. They appear in potentials that are shallower than quadratic away from the minimum and can be extremely long-lived.
Since plateau models are of great relevance for inflation, oscillons have been shown to form efficiently during preheating in a wide range of such models. Their formation and decay are...
Artificial neural networks can model nonlinear relationships in datasets. In observational cosmology there are many situations involving complex datasets, therefore in this talk we present some applications of neural networks in the framework of cosmological data analysis. We use observational data and numerical simulations; the tasks we have tackled with neural networks have been...
Dynamical system formulation is an important qualitative tool now widely used in
cosmology to understand the cosmological solution space of a theory. A number of
dynamical system formulations have been proposed over the last few years to analyse
cosmological solutions in f(R) gravity. I will try to give a brief introduction to the
di↵erent approaches, presenting them in a chronological...
When generalized noncommutative Heisenberg algebra accommodating gravitational field as specified by string theory, for instance, is thoughtfully applied on Finsler manifold, the quantized metric tensor could be defined. By constructing the affine connections on pseudo--Riemannian manifold, quantization of Riemann curvature tensor and its unique contractions, Ricci curvature tensor and scalar,...
In the geometric optics regime gravitational lensing is an achromatic phenomenon. However, certain physical situations require wave optics to be taken into account, such that the deflection angle becomes wavelength dependent and the interference between multiple images must be taken into account. These effects are particularly relevant in the case of lensing by low mass compact objects, such...
Astrophysical observations are largely based on electromagnetic signals still read with the Maxwellian massless and linear theory, possibly an approximation of a larger theory, as Newtonian gravity is for Einsteinian gravity in weak fields. Photons are the sole free massless particles in the Standard-Model (SM). Apart from massive formalisms (de Broglie-Proca, Bopp, Stueckelberg and others),...
Black Holes with masses of the order of $10^{14}$g would be evaporating today, which could have been formed in the beginning of the universe. On the other hand, Fast Radio Bursts are thought to be associated to compact objects with extreme magnetic fields. Starting from V. Manko's solution of the Einstein Equations for a Rotating Black Hole with a magnetic field, it's emission properties are...
The problems with the stantard model of cosmology $\Lambda$CDM are well-known, such as the origin and behaviour of Dark Matter and Dark Energy or some tensions with the inferred value of some parameters when using distinct data sets, and several solutions have been proposed. One approach to try and elucidate the nature of the Dark Energy and relieve the parameter tensions is through...
Spectroscopic redshifts ($z$) are obtained through the spectra of astronomical objects, this process is time-consuming, expensive, and frequently impossible for large numbers of galaxies due to telescope time limitations. Thus, in order to find this parameter $z$, in this work, we use the photometry of galaxies to determine this same quantity. Photometric redshifts can be evaluated through the...
In the first stages of inflationary reheating, the mean energy of the radiation produced by inflaton decay is higher than the commonly defined reheating temperature. In thermal equilibrium, particle production can then be significantly enhanced relative to the subsequent radiation dominated era. Furthermore, in the earliest stages of reheating, before thermalization takes place, scattering of...
I will talk about Bianchi cosmologies coupled to a matter source that has the field theoretical description of a solid. Models of solid inflation are known for not being very efficient in diluting away anisotropy. While confirming this fact, our study finds another potential feature of solid inflation, namely a ``rotation” of the principal axes of the expansion. Such a rotation is not just a...
The inflationary origin of primordial black holes (PBHs) relies on a large enhancement of the power spectrum of the curvature fluctuation ζ at wavelengths much shorter than those of the CMB anisotropies. Quantum gravity inspired models are characterized by moduli spaces with highly curved geometries and a large number of scalar fields that could vigorously interact with ζ (as in the...
The Cosmology Large Angular Scale Surveyor (CLASS) is a set of four ground-based telescopes designed to measure and characterize the polarization signal of the cosmic microwave background (CMB) on the largest angular scales in order to probe the epochs of inflation and reionization. Located in a high-altitude site in the Atacama Desert, CLASS covers 70% of the sky in frequency bands centered...
The observation of neutrino flavor oscillations by various experiments involving both natural (solar and atmospheric) and man-made (accelerators and reactors) neutrino sources firmly indicates that neutrinos are massive particles.
In fact, all these experiments can be well understood if we assume the so-called {\it Standard Paradigm} that is, that the three known neutrino interaction...
The particle concept in curved space-time is, in general, observer de-
pendent, as is well-known from the Unruh effect. This, in particular, is
really important to understand the particle emission from black holes. In
this work, we study the Unruh effect under the perspective of De Broglie-
Bohm interpretation of quantum mechanics, where from the wave func-
tional we obtain the associated...
