IWARA2020 Video Conference - 9th International Workshop on Astronomy and Relativistic Astrophysics

Session

DM, DE, GWs, BHs, GRAVITATION, GALAXIES, QCD, LIFE, GRBs, COSMOLOGY, OA, KT

11 Sept 2020, 12:30

178. 21 cm cosmology and the BINGO radio telescope

Carlos Alexandre Wuensche (National Institute for Space Research – INPE)

11/09/2020, 12:30

Talk

Cosmology in the XXI century is experiencing a "Golden Age", with observations and theoretical models contributing to a large-scale description of the Universe. The current view is that it can be well described by the so-called Lambda-CDM model, but some open problems challenge physics and cosmology, including the origin and properties of so-called dark energy. The so-called baryonic acoustic...

109. Accretion-induced collapse to third family compact stars as trigger for eccentric orbits of millisecond pulsars in binaries

David Edwin Alvarez Castillo (JINR)

11/09/2020, 12:37

Talk

A numerical rotating neutron star solver is used to study the temporal evolution of accreting neutron stars using a multi-polytrope model for the nuclear equation of state named ACB5. The solver is based on a quadrupole expansion of the metric, but confirms the results of previous works, revealing the possibility of an abrupt transition of a neutron star from a purely hadronic branch to a...

186. The magnetized photon: properties and astrophysical applications

Elizabeth Rodriguez Querts (Instituto de Cibernética, Matemática y Física – ICIMAF)

11/09/2020, 12:44

Talk

We study the properties of photon propagation both in QED vacuum and medium, taking into account radiative corrections, in an external magnetic field. We explore possible applications of the results in an astrophysical context.

174. Hybrid star with non interacting dark matter fermion core

Fábio Köpp (Universidade Federal do Rio Grande do Sul – UFRGS)

11/09/2020, 12:51

Talk

In this work we study the influences of the dark matter fermion mass on the structure of the hybrid star. We fixed the Fermi momentum of dark matter and considered the mass of dark matter from 0.1 GeV to 100 GeV, since the mass of dark matter is more uncertain than its density approximation related to ordinary matter. Further, we used the Maxwell construction to make the phase transition...

194. Study of diffractive gluon jet production in electron-ion collisions

Guilherme Peccini (Universidade Federal do Rio Grande do Sul – UFRGS)

11/09/2020, 12:58

Talk

In this work we investigate the diffractive gluon jet production in electron-ion collisions at the energies of the EIC, LHeC, HE-LHeC and FCC-eA, assuming that the diffractive mass is much larger than the photon virtuality. In addition, we apply a model inspired in the GBW parametrization to describe the dipole amplitude, showing that the diffractive cross section is highly sensitive to the...

192. Hawking-Bekenstein temperature and entropy from uncertainty principle

Hugo Pérez Rojas (Instituto de Cibernética, Matemática y Física – ICIMAF)

11/09/2020, 13:05

Talk

We give an alternative way for deducing the Hawking-Bekenstein black hole temperature and entropy by using the Heisenberg uncertainty principle. We consider as known the black hole mass as M and consequently its energy. Quantities as temperature T and entropy S can be found under the hypothesis that incoming radiation and matter leads to a thermodynamic equilibrium state. Obviously this is not...

196. Axial ring down modes in General Relativity and in its pseudo-complex extension

Peter Hess (National Autonomous University of Mexico - UNAM)

11/09/2020, 13:12

Talk

We calculate the axial ring-down frequencies of the merger of two black holes, using a modified version of the pseudo-complex General Relativity (pc-GR) and comparing it with the standard General Relativity (GR).

193. Modeling Dark Matter Halos With Nonlinear Field Theories

Pedro Henrique Ribeiro da Silva Moraes (Instituto de Astronomia, Geofísica e Ciências Atmosféricas – IAG, Universidade de São Paulo – USP)

11/09/2020, 13:19

Talk

In the present work we show that it is possible to model galactic dark matter from nonlinear scalar field theories coupled to the gravity sector. In order to obtain analytical solutions for the scalar fields we consider a spherically symmetric space-time. We also assume a theoretical framework where dark matter consists of a complex scalar field, which is responsible for producing galactic...

175. The Physics of twin stars

Rosana Oliveira Gomes (Frankfurt Insitute for Advanced Studies)

11/09/2020, 13:26

Talk

In this contribution, we investigate the possibility of a third family of compact stars under different scenarios. First, we will focus on the microscopic description of stars and discuss how different properties of matter can influence the rising of twin stars. For doing so, we carry out an analysis of different parameters used to describe hadronic and quark matter with relativistic mean...

114. Gaussian Process Estimation of Transition Redshift

Prof. Rodolfo Valentim (UNIFESP - Diadema)

Poster

This poster aims to put constraints on the transition redshift $z_t$, which determines the onset of cosmic acceleration, in cosmological-model independent frameworks. In order to do that, we use the non-parametric Gaussian Process method with $H(z)$ and SNe Ia data. The deceleration parameter reconstruction from $H(z)$ data yields $z_t=0.59^{+0.12}_{-0.11}$. The reconstruction from SNe Ia...

163. Identifying Protoclusters in Distant Universe

Mariana Costa (Federal University of Rio de Janeiro)

Poster

Properties of galaxies, such as color, age and star formation activity, appear to be associated with the environment in which they are immersed. To investigate how environment influences galaxy evolution, astronomers study galaxies in dense regions (i.e., galaxy clusters), where the environmental effects become more intense and evident. However, to study how the environment-galaxy relation is...

115. Kinematic Constraints on Spatial Curvature from Supernovae Ia and Cosmic Chronometers

Rodolfo Valentim (UNIFESP - Diadema)

Poster

This work has an interesting approach to estimate the spatial curvature $\Omega_k$ from data independently of dynamical models is suggested, it was done through three kinematic parameterizations of the comoving distance ($D_{C}(z)$) with second degree polynomial, of the Hubble parameter ($H(z)$) with a second degree polynomial and of the deceleration parameter ($q(z)$) with first order...

133. Observational Constraints on the possibility that Sterile Neutrinos cause Anti-gravity

Ms Priyamvada Kameshwar (University of Delhi)

Poster

The origin of neutrino masses heralds new physics. Some theories that explain small neutrino masses, predict the existence of sterile neutrinos. Observationally, there is no evidence that neutrinos cause attractive gravity. Exploring a new idea, we study constraints posed by data as to what if sterile neutrinos cause repulsive gravity. We use an effective negative gravitational constant (-G')...

141. The way of entropy: From Big-Bang to infinite

Nilo Serpa (Centro Universitário ICESP)

Poster

In principle, our model serves to reopen the discussion on possible metrics in a thermodynamic manifold, since we can speak of an extensive variable, the "distance" (duration) in a temporal manifold. Furthermore, the multiplier equilibrium constant β is inherited from the power of the time interval in kets, in such a way that we could, so to speak, associate entropy with a "metric index"...