arXiv subjects

R. Silva

Publications and source records attributed to R. Silva.

At least 19 recordsLinked to original sources

arXiv2025

Forecasting constraints on quintessential inflation from future generation of galaxy and CMB surveys

We investigate the constraining power of future CMB and galaxy surveys on models of quintessential inflation realized within the framework of $\alpha$-attractors. We analyze how these future datasets will probe the parameter space of $\alpha$-attractor quintessential inflation, specifically the inflationary potential parameters. Our results demonstrate that the synergy between CMB-S4, LiteBIRD, and Euclid can significantly tighten the bounds on the model parameters, achieving forecasted $1\sigma$ uncertainties of $\alpha=2\pm 0.17$, $n_s=0.965\pm 0.0014$, $\ln(10^{10}A_s)=3.0447\pm 0.0029$ for the CMB+GC$_{sp}$ case. This level of sensitivity will enable us to discriminate between different realizations of quintessential inflation and test the attractor behavior characteristic of these models.

astro-ph.CO↗

arXiv2025

A Joint Analysis of Strong Lensing and Type Ia Supernovae to Determine the Hubble Constant

We present a cosmological model-independent determination of the Hubble constant, $H_0$, by combining time-delay measurements from seven TDCOSMO systems, Einstein radius measurements, and Type Ia Supernovae data sourced from the Pantheon+ sample. For each lens of time-delay system, we calculate the angular diameter distance $D_{A_l}$ using the product $D^{\textrm{Obs}}(z_l) \cdot D_{A,\Delta t}^{\textrm{Obs}}(z_l, z_s)$, where $D^{\textrm{Obs}}(z_l)$ is reconstructed via Gaussian Processes from 99 Einstein radius measurements, and $D_{A,\Delta t}^{\textrm{Obs}}(z_l,z_s)$ is the time-delay angular distance. We also reconstruct the unanchored luminosity distance $H_0 D_L(z_l)$ from supernova data. By using the cosmic distance duality relation validity, we anchor $D_{A_l}$ and $H_0 D_L(z_l)$ to infer $H_0 = 70.55 \pm 7.44$ km/s/Mpc (68\% CL). Our result, though not resolving the Hubble tension, offers a cosmological model-independent consistency check and highlights the potential of using strong lensing and supernovae data via the cosmic distance duality relation to constrain $H_0$.

astro-ph.CO↗

arXiv2025

Brazilian Report on Dark Matter 2024

One of the key scientific objectives for the next decade is to uncover the nature of dark matter (DM). We should continue prioritizing targets such as weakly-interacting massive particles (WIMPs), Axions, and other low-mass dark matter candidates to improve our chances of achieving it. A varied and ongoing portfolio of experiments spanning different scales and detection methods is essential to maximize our chances of discovering its composition. This report paper provides an updated overview of the Brazilian community's activities in dark matter and dark sector physics over the past years with a view for the future. It underscores the ongoing need for financial support for Brazilian groups actively engaged in experimental research to sustain the Brazilian involvement in the global search for dark matter particles

hep-ph↗

arXiv2025

The CMS Barrel Timing Layer: test beam confirmation of module timing performance

First of its kind, the barrel section of the MIP Timing Detector is a large area timing detector based on LYSO:Ce crystals and SiPMs which are required to operate in an unprecedentedly harsh radiation environment (up to an integrated fluence of $2\times10^{14}$ 1 MeV $n_{eq}/cm^2$). It is designed as a key element of the upgrade of the existing CMS detector to provide a time resolution for minimum ionizing particles in the range between 30-60 ps throughout the entire operation at the High Luminosity LHC. A thorough optimization of its components has led to the final detector module layout which exploits 25 $\rm \mu m$ cell size SiPMs and 3.75 mm thick crystals. This design achieved the target performance in a series of test beam campaigns. In this paper we present test beam results which demonstrate the desired performance of detector modules in terms of radiation tolerance, time resolution and response uniformity.

physics.ins-det↗

arXiv2024

Interaction in the dark sector: a phenomenological approach

The non-gravitational interaction between the dark components of the Universe could lead to the variation of dark matter energy density standard evolution law. When we assume this scenario, the dark matter energy density follows $\rho_{{dm}}\sim(1+z)^{3 + \epsilon(z)}$ (where $\epsilon(z)=0$ the standard law is recovered). In this paper, we perform a Bayesian analysis to test three parameterizations for $\epsilon(z)$, namely: $\epsilon(z)=\epsilon_0$, $\epsilon(z)=\epsilon_0 + \epsilon_1\frac{z}{1+z}$ and $\epsilon(z)=\epsilon_0 + \epsilon_1\frac{z(1+z)}{1+z^2}$, where the first one is motivated through the fundamental grounds and the others are on the phenomenological ones. Through the Gaussian process regression, our method uses galaxy cluster gas mass fraction measurements, SNe Ia observations, Cosmic Chronometers, and BAO data. No specific cosmological model is considered. In all possibilities analyzed, the standard evolution law ($\epsilon(z)=0$) is within $2\sigma$ c.l. The investigated cases generally indicated scenarios of inconclusive or weak evidence toward the simplest model from the Bayesian standpoint.

astro-ph.CO↗

arXiv2024

TOFHIR2: The readout ASIC of the CMS Barrel MIP Timing Detector

The CMS detector will be upgraded for the HL-LHC to include a MIP Timing Detector (MTD). The MTD will consist of barrel and endcap timing layers, BTL and ETL respectively, providing precision timing of charged particles. The BTL sensors are based on LYSO:Ce scintillation crystals coupled to SiPMs with TOFHIR2 ASICs for the front-end readout. A resolution of 30-60 ps for MIP signals at a rate of 2.5 Mhit/s per channel is expected along the HL-LHC lifetime. We present an overview of the TOFHIR2 requirements and design, simulation results and measurements with TOFHIR2 ASICs. The measurements of TOFHIR2 associated to sensor modules were performed in different test setups using internal test pulses or blue and UV laser pulses emulating the signals expected in the experiment. The measurements show a time resolution of 24 ps initially during Beginning of Operation (BoO) and 58 ps at End of Operation (EoO) conditions, matching well the BTL requirements. We also showed that the time resolution is stable up to the highest expected MIP rate. Extensive radiation tests were performed, both with x-rays and heavy ions, showing that TOFHIR2 is not affected by the radiation environment during the experiment lifetime.

physics.ins-det↗

arXiv2023

Updated Big Bang Nucleosynthesis Bounds on Long-lived Particles from Dark Sectors

As electromagnetic showers may alter the abundance of Helium, Lithium, and Deuterium, we can place severe constraints on the lifetime and amount of electromagnetic energy injected by long-lived particles. Considering up-to-date measurements of the light element abundances that point to $Y_p=0.245\pm 0.003$, $({\rm D/H})= (2.527\pm 0.03)\times 10^{-5}$, and the baryon-to-photon ratio obtained from the Cosmic Microwave Background data, $\eta=6.104 \times 10^{-10}$, we derive upper limits on the fraction of electromagnetic energy produced by long-lived particles. Our findings apply to decaying dark matter models, long-lived gravitinos, and other non-thermal processes that occurred in the early universe between $10^2-10^{10}$ seconds.

hep-ph↗

arXiv2023

Non-Parametric Analysis for the Dark Matter Density Evolution

In this paper, we investigate a potential departure in the standard dark matter density evolution law, $\rho_{dm} = \rho_{dm,0}(1+z)^3$. The method involves considering a deformed evolution model, denoted as $\rho_{dm} = \rho_{dm,0}(1+z)^3f(z)$, and searching the presence of any deviation ($f(z)\neq 1$). As one may see, $f(z)$ is a general function that parametrizes a possible digression from the standard law. We use data of baryon acoustic oscillations, type I Supernovae luminosity distances, and galaxy cluster gas mass fraction observations to reconstruct $f(z)$ through an approach that is not dependent on the cosmological model or the so-called Gaussian process regression. Unlike previous works, it enables us to investigate a possible deviation without using a specific function to describe it. We have obtained $f(z)=1$, the standard model scenario, within $2\sigma$ c.l. in all the considered cases.

astro-ph.CO↗

arXiv2023

Constraints on the non-minimally coupled Witten-O'Raifeartaigh inflation

We investigate the impact of a non-minimal coupling of the scalar field with gravity in inflationary models, where a small coupling is allowed. As a concrete example, we consider the Witten-O'Raifeartaigh model, where, in line with other models, the presence of a coupling strength $\xi$ can recover concordance of the inflationary parameters with cosmic microwave background (CMB) constraints, provided by the Planck collaboration. We go beyond the slow-roll regime and investigate the impact in the description of CMB anisotropies by performing a statistical analysis of the model with the most recent Planck + Baryon Acoustic Oscillations (BAO) data to seek for any indication of a non-zero coupling by data within the model. We find that not only the presence of a non-minimal coupling is seen, but the model has a slight statistical preference when compared with the standard $\Lambda$CDM one. We also discuss the results on the minimally-coupled model, which in general, favours the simple setting where the associated mass scale is equal to the reduced Planck mass $M_p$ while being, in general, disfavored concerning the standard model.

astro-ph.CO↗

arXiv2022

Warm $\beta$-exponential inflation and the Swampland Conjectures

We investigate theoretical and observational aspects of a warm inflation scenario driven by the $\beta$-exponential potential, which generalizes the well-known power law inflation. In such a scenario, the decay of the inflaton field into radiation happens during the inflationary phase. In our study, we consider a dissipation coefficient ($\Gamma$) with cubic dependence on the temperature ($T$) and investigate the consequences in the inflationary dynamics, focusing on the impact on the spectral index $n_s$, its running $n_{run}$ and tensor-to-scalar ratio $r$. We find it possible to realize inflation in agreement with current cosmic microwave background data in weak and strong dissipation regimes. We also investigate theoretical aspects of the model in light of the swampland conjectures, as warm inflation in the strong dissipation regime has been known as a way to satisfy the three conditions currently discussed in the literature. We find that when $\Gamma\propto T^3$, the $\beta$-exponential model can be accommodated into the conjectures.

astro-ph.CO↗

arXiv2022

Revisiting Witten-O'Raifeartaigh Inflation for a Non-minimally Coupled Scalar Field

In this work, we revisit the Witten-O'Raifeartaigh model of inflation, in which the potential takes a $\operatorname{log}^2(\phi/M)$ form, when the scalar field is non-minimally coupled to gravity. We investigate the impact of the coupling in the prediction of the inflationary parameters, thereby affecting the viability of the model. We find that a small coupling of order $\xi\sim10^{-3}$ is preferred by data at the $n_s-r$ plane level, and that the presence of a non-zero $\xi$ allows for a large interval of the mass scale $M$, in which it is possible to achieve a low tensor-to-scalar ratio. We also establish constraints imposed by a subsequent reheating era, in which its duration and temperature can be related to CMB observables, which in return, restricts the possible values for the $n_s$ and $r$ parameters.

astro-ph.CO↗

arXiv2021

Observational Constraints on $f(T)$ Gravity from Model-Independent Data

We establish new constraints on $f(T)$ gravity models by using cosmological data. In particular, we investigate the restrictions given by the gas mass fraction measurements of galaxy clusters and transversal BAO data. Both data sets are regarded as weakly dependent on a fiducial cosmology. In addition, we also include a CMB measurement of the temperature power spectrum first peak, along with $H(z)$ values from cosmic chronometers and supernovae data from the Pantheon data set. We also perform a forecast for future constraints on the deviation of $f(T)$ models from the $\Lambda$CDM scenario by following the specifications of the J-PAS and Euclid surveys and find significant improvements on the constraints of the $b$-parameter, when compared to the results of the statistical analysis.

astro-ph.CO↗

arXiv2021

An outlier-resistant $\kappa$-generalized approach for robust physical parameter estimation

In this work we propose a robust methodology to mitigate the undesirable effects caused by outliers to generate reliable physical models. In this way, we formulate the inverse problems theory in the context of Kaniadakis statistical mechanics (or $\kappa$-statistics), in which the classical approach is a particular case. In this regard, the errors are assumed to be distributed according to a finite-variance $\kappa$-generalized Gaussian distribution. Based on the probabilistic maximum-likelihood method we derive a $\kappa$-objective function associated with the finite-variance $\kappa$-Gaussian distribution. To demonstrate our proposal's outlier-resistance, we analyze the robustness properties of the $\kappa$-objective function with help of the so-called influence function. In this regard, we discuss the role of the entropic index ($\kappa$) associated with the Kaniadakis $\kappa$-entropy in the effectiveness in inferring physical parameters by using strongly noisy data. In this way, we consider a classical geophysical data-inverse problem in two realistic circumstances, in which the first one refers to study the sensibility of our proposal to uncertainties in the input parameters, and the second is devoted to the inversion of a seismic data set contaminated by outliers. The results reveal an optimum $\kappa$-value at the limit $\kappa \rightarrow 2/3$, which is related to the best results.

cond-mat.stat-mech↗

arXiv2020

Growth of matter perturbations in the extended viscous dark energy models

In this work, we study the extended viscous dark energy models in the context of matter perturbations. To do this, we assume an alternative interpretation of the flat Friedmann-Lema\^itre-Robertson-Walker Universe, through the nonadditive entropy and the viscous dark energy. We implement the relativistic equations to obtain the growth of matter fluctuations for a smooth version of dark energy. As result, we show that the matter density contrast evolves similarly to the $\Lambda$CDM model in high redshift; in late time, it is slightly different from the standard model. Using the latest geometrical and growth rate observational data, we carry out a Bayesian analysis to constrain parameters and compare models. We see that our viscous models are compatible with cosmological probes, and the $\Lambda$CDM recovered with a $1\sigma$ confidence level. The viscous dark energy models relieve the tension of $H_0$ in $2 \sim 3 \sigma$. Yet, by involving the $\sigma_8$ tension, some models can alleviate it. In the model selection framework, the data discards the extended viscous dark energy models.

astro-ph.CO↗

arXiv2020

Cosmological perturbations in the Tsallis holographic dark energy scenarios

We investigate the Tsallis holographic dark energy (THDE) models in the context of perturbations' growth. We assume the description of dark energy by considering the holographic principle and the nonadditive entropy to carry out this. We implement the perturbed relativistic equations to achieve the growth of matter fluctuations, being the growth rate of the cosmic structures is non-negligible at low redshifts. To constrain and compare the models, we carry out the Bayesian analysis using the recent geometrical and growth rate observational data. The main results are: (i) the models are compatible with cosmological observations, (ii) the cosmological constant recovered with a $1\sigma$ confidence level, furthermore (iii) they could cross the phantom barrier. Finally, the models can relieve $\approx 1\sigma$ the $\sigma_8$ tension in the non-clustered case and can alleviate in $\approx 2.8\sigma$ the $H_0$ tension. From the model selection viewpoint, the data discarded the THDE models.

astro-ph.CO↗

arXiv2020

Thermodynamic Constraints on the Dark Sector

In this paper, we present a unified scheme based on the fluid description of the dark sector of the universe. The scheme captures models with interaction between dark energy and dark matter, being the core of generalization the time-varying equation-of-state parameter $\omega(a)$ and the time-dependent interactions through the interaction function $\epsilon(a)$, where $a$ is the scale factor. Furthermore, we propose thermodynamics constraints on this generalized class of models using the laws of thermodynamics which are combined with observational data. In order to test the observational viability of the unified model, we perform a Bayesian analysis using cosmic chronometers, type Ia supernovae, cosmic microwave background, and angular baryon acoustic oscillation measurements.

astro-ph.CO↗

arXiv2020

Brane inflation and the robustness of the Starobinsky inflationary model

The first inflationary model conceived was the one proposed by Starobinsky which includes an additional term quadratic in the Ricci-scalar R in the Einstein-Hilbert action. The model is now considered a target for several future cosmic microwave background experiments given its compatibility with current observational data. In this paper, we analyse the robustness of the Starobinsky inflation by inserting it into a generalized scenario based on a $\beta$-Starobinsky inflation potential, which is motivated through brane inflation. In the Einstein frame, the generalized model recovers the original model for $\beta=0$, whereas $\forall \beta \neq 0$ represents an extended class of models that admit a wider range of solutions. We investigate limits on $\beta$ from current cosmic microwave background and baryonic acoustic oscillation data and find that only a small deviation from the original scenario is allowed, $\beta=-0.08 \pm 0.12$ (68% C.L.), which is fully compatible with zero and confirms the robustness of the Starobinsky inflationary model in light of current observations.

astro-ph.CO↗

arXiv2020

Bayesian Comparison of the Cosmic Duality Scenarios

The cosmic distance duality relation (CDDR), $D_{\rm L}(1+z)^{-2}/D_{\rm A}=\eta=1$, with $D_{\rm L}$ and $D_{\rm A}$, being the luminosity and angular diameter distances, respectively, is a crucial premise in cosmological scenarios. Many investigations try to test CDDR through observational approaches, even some of these ones also consider a deformed CDDR, i.e., $\eta=\eta(z)$. In this paper, we use type Ia supernovae luminosity distances and galaxy cluster measurements (their angular diameter distances and gas mass fractions) in order to perform a Bayesian model comparison between $ \eta(z) $ functions. We show that the data here used are unable to pinpoint, with a high degree of Bayesian evidence, which $\eta(z)$ function best captures the evolution of CDDR.

astro-ph.CO↗