A5091022702- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Dark Matter and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Advanced Thermodynamics and Statistical Mechanics
- Geophysics and Sensor Technology
- Adaptive optics and wavefront sensing
- Hydrology and Drought Analysis
- Advanced Differential Geometry Research
- Particle Detector Development and Performance
- Image and Signal Denoising Methods
- Advanced Clustering Algorithms Research
- Space Technology and Applications
- Advanced Numerical Methods in Computational Mathematics
- Health, Education, and Aging
Valongo Observatory
2016-2024
Universidade Federal do Rio de Janeiro
2014-2024
Centro Brasileiro de Pesquisas Físicas
2023-2024
Fermi National Accelerator Laboratory
2009-2012
Cosmological models involving an interaction between dark matter and energy have been proposed in order to solve the so-called coincidence problem. Different forms of coupling studied, but there claims that observational data seem narrow (some of) them down something annoyingly close ΛCDM (CDM: cold matter) model, thus greatly reducing their ability deal with problem first place. The smallness initial density has also a target cosmological recent years. Making use moderately general scheme,...
The Southern Photometric Local Universe Survey (S-PLUS) is imaging ~9300 deg^2 of the celestial sphere in twelve optical bands using a dedicated 0.8 m robotic telescope, T80-South, at Cerro Tololo Inter-American Observatory, Chile. telescope equipped with 9.2k by e2v detector 10 um pixels, resulting field-of-view 2 plate scale 0.55"/pixel. survey consists four main subfields, which include two non-contiguous fields high Galactic latitudes (8000 |b| > 30 deg) and areas plane bulge (for an...
We present an analysis of supernova light curves simulated for the upcoming Dark Energy Survey (DES) search. The simulations employ a code suite that generates and fits realistic in order to obtain distance modulus/redshift pairs are passed cosmology fitter. investigated several different survey strategies including field selection, selection biases, photometric redshift measurements. Using results this study, we chose 30 deg2 search area griz filter set. forecast (1) will provide...
We use type Ia supernovae (SN Ia) data in combination with recent baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) observations to constrain a kink-like parametrization of the deceleration parameter ($q$). This $q$-parametrization can be written terms initial ($q_i$) present ($q_0$) values parameter, redshift transition from acceleration ($z_t$) width such ($\tau$). By assuming flat space geometry, $q_i=1/2$ adopting likelihood approach deal SN we obtain, at 68%...
We revisit the kink-like parametrization of deceleration parameter q(z), which considers a transition, at $z_t$, from cosmic to acceleration. In this initial, $z \gg z_t$, value q-parameter is $q_i$, its final, z=-1, $q_f$ and duration transition parametrized by $\tau$. By assuming flat space geometry we obtain constraints on free parameters model using recent data type Ia supernovae, BAO, CMB Hubble H(z). The use H(z) introduces an explicit dependence combined likelihood present $H_0$,...
The Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) is a narrow band, very wide field Cosmological to be carried out from Javalambre Observatory in Spain with purpose-built, dedicated 2.5m telescope and 4.7 sq.deg. camera 1.2Gpix. Starting late 2015, J-PAS will observe 8500sq.deg. Northern Sky measure $0.003(1+z)$ photo-z for $9\times10^7$ LRG ELG galaxies plus several million QSOs, sampling an effective volume $\sim 14$ Gpc$^3$ up $z=1.3$ becoming first radial...
We examine the static structure configurations and radial stability of compact stars within context $f(R, T)$ gravity, with $R$ $T$ standing for Ricci scalar trace energy-momentum tensor, respectively. Considering T)=R+2\beta T$ functional form, $\beta$ being a constant, we derive corresponding hydrostatic equilibrium equation modified Chandrasekhar's pulsation equation. The mass-radius relations mode frequencies are obtained some realistic equations state. Our results show that traditional...
Abstract We investigate the equilibrium and radial stability of spherically symmetric relativistic stars, considering a polytropic equation state (EoS), within framework f(R,T) gravity with conservative energy-momentum tensor. Both modified stellar structure equations Chandrasekhar's pulsation are derived for f(R,T)= R+ h(T) model, where function assumes specific form in order to safeguard conservation The neutron star properties, such as radius, mass, binding energy oscillation spectrum...
Stripe 82 in the Sloan Digital Sky Survey was observed multiple times, allowing deeper images to be constructed by coadding data. Here we analyze ellipticities of background galaxies this 275 square degree region, searching for evidence distortions due cosmic shear. The E-mode is detected both real and Fourier space with $>5$-$\sigma$ significance on scales, while B-mode consistent zero as expected. amplitude signal constrains combination matter density $\Omega_m$ fluctuation $\sigma_8$...
The photometric redshift estimation (photo-z) has been developed over the years with various methods. In this work, we analyse four different photo-z estimators using Dark Energy Survey Y3 BAO Sample: \texttt{ANNz2}, \texttt{BPZ}, \texttt{ENF}, and \texttt{DNF}. Unlike what is usually found in literature, investigate possibility of selecting best galaxies according to their Probability Distribution Function (PDF). We selected 25,760 from spectroscopic surveys cross-matched them sample. These...
Photometric surveys are good solutions for large-scale structure studies. The Baryon Acoustic Oscillations (BAO) benefit from photometric redshift survey observations due to faster coverage and a higher number of observed objects. In the present study, we use Dark Energy Survey Year 3 catalog Luminous Red Galaxies (LRG) realistic galaxies' Probability Distribution Function (PDF) that describes each galaxy select samples include in fitting model as input uncertainty. We used four different...
We show that entropy perturbations can eliminate instabilities and oscillations in the mass power spectrum of quartessence Chaplygin models. Our results enlarge current parameter space models compatible with large-scale structure cosmic microwave background observations.
It has been argued that by removing a pressure gradient term in the continuity equation, it is possible to obtain, with semiclassical formulation, same expression for density contrast growing mode, as obtained full relativistic treatment. In this context, we reinvestigate evolution of perturbations an expanding Newtonian universe pressure, but consider general scenario which equation state parameter time dependent and are not necessarily adiabatic. We verify that, case, suggested...
We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. use Artificial Neural Network (ANN) technique to calculate photo-z's Nearest Neighbor Error (NNE) method estimate photo-z errors $\sim$ 13 million objects classified as galaxies in coadd with $r < 24.5$. The error estimators are trained validated on sample $\sim 83,000$ that have SDSS photometry spectroscopic measured by Data Release 7 (DR7), Canadian...
Abstract We provide the modified TOV equations for hydrostatic equilibrium of charged compact stars within metric f ( R ) gravitational background. adopt MIT bag model EoS dense matter and assume a charge distribution where electric density ρ ch is proportional to standard energy . Using Starobinsky model, we explore role αR 2 term, α free constant Ricci scalar, on global properties such as radius, mass total charge. present dependence structure star several values different parameter β ≡ /...
Quartessence is one of the alternatives to $\ensuremath{\Lambda}\mathrm{CDM}$ that has lately attracted considerable interest. According this unifying dark matter/energy scenario, Universe evolved from an early nonrelativistic matter-dominated phase a more recent accelerated expansion phase, driven by single fluid component. Recently, it been shown some problems quartessence model, such as existence instabilities and oscillations in matter power spectrum, can be avoided if specific type...
In the metric approach of $f(R)$ theories gravity, fourth-order field equations are often recast as effective Einstein in presence standard matter and a curvature fluid (which gathers all extra terms), always Jordan frame. this picture, we investigate strong gravity regime $f(R) = R+ \alpha R^2$ model. particular, focus on stability compact star composed by mixture ordinary -- described polytropic equation state an otherwise so that able to apply usual govern radial adiabatic oscillations...
We investigate the structure of quark stars in framework $f(R)= R+ \alpha R^2$ gravity using an equation state for cold matter obtained from perturbative QCD, parametrized only by renormalization scale. show that a considerably large range free parameter $\alpha$, within and even beyond constraints previously reported literature, yield non-negligible modifications mass radius with central densities. Besides, their stability against baryon evaporation is analyzed through behavior associated...
Light is the richest information retriever for most physical systems, particularly so astronomy and cosmology, in which gravitation of paramount importance, also solid state defects metamaterials, some effects can be mimicked by non-Euclidean or even non-Riemannian geometries. Thus, it expedient to probe light motion geometrical backgrounds alternative that general relativity. Here we investigate this issue generic metric-affine theories derive (i) expression, optics (eikonal) limit,...
We describe and present initial results of a weak lensing survey nearby (z ≲ 0.1) galaxy clusters in the Sloan Digital Sky Survey (SDSS). In this first study, are selected from SDSS spectroscopic cluster catalogs Miller et al. Berlind report total seven individual low-redshift measurements that include A2048, A1767, A2244, A1066, A2199, two specifically identified with C4 algorithm. Our program will eventually reach ∼200 clusters, making it largest to date.
By using the Sloan Digital Sky Survey (SDSS) first year type Ia supernova (SN Ia) compilation, we compare two different approaches (traditional \chi^2 and complete likelihood) to determine parameter constraints when magnitude dispersion is be estimated as well. We consider cosmological constant + Cold Dark Matter (\Lambda CDM) spatially flat, w Energy (FwCDM) models show that, for current data, there a small difference in best fit values $\sim$ 30% confidence contour areas case MLCS2k2...
The efficient classification of different types supernova is one the most important problems for observational cosmology. However, spectroscopic confirmation objects in upcoming photometric surveys, such as Rubin Observatory Legacy Survey Space and Time (LSST), will be unfeasible. development automated processes based on photometry has thus become crucial. In this paper we investigate performance machine learning (ML) final cosmological constraints using simulated lightcurves from Supernova...
Abstract The Baryon Acoustic Oscillations (BAO) are one of the most used probes to understand accelerated expansion Universe. Traditional methods rely on fiducial model information within their statistical analysis, which may be a problem when constraining different families models. This work aims provide method that constrains $$\theta _{BAO}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>θ</mml:mi> <mml:mrow> <mml:mi>BAO</mml:mi> </mml:mrow> </mml:msub>...