The lack of information on the nature of the neutron star (NS) core at supra-nuclear densities, has so far prevented a unique description of its equation of state (EoS). Future gravitational wave (GW) detections by second and third-generation of ground-based interferometers will shed new light on this open problem. The income of new and detailed experimental data will help to reconstruct the...
We study the static spherically symmetric configurations of the perfect fluid described by the polytropic equation of state (EoS) in the $f(T)$ extended theory of gravity. For $f(T) = T$ , where $T$ is the torsion scalar, this gravity theory is equivalent to GR and is known as its teleparallel equivalent (TEGR). In this work, we provide numerical evidence for the existence of the polytropic...
In this poster, I will present results from a recent study aimed at finding the most plausible Equation of State (EoS) for neutron star matter, combining available first principles calculations with up-to-date observational data. Our EoSs are composed of piecewise polytropes interpolating between known limits from quantum Monte Carlo at low densities and perturbative QCD at high densities....
Neutron stars are one of the most compact objects in the universe. They are made of a totally degenerated fermion gas, but their interior composition remains unknown. Several scenarios exist and some of them predict phase transitions from ordinary nuclear matter to mesons condensates, hyperonic matter, quark gluon plasma in the core, or even absolutely stable strange quark matter. In order to...
Equation of state of nuclear matter using AV8’ and AV6’ potentials
Z. Asadi and M. Bigdeli
Department of Physics, University of Zanjan, Zanjan, Iran
The equation of state (EOS) of asymmetric nuclear matter have long been realized as a crucial parameter to understand the structural properties of neutron-rich nuclei and neutron stars. The behavior of the EOS of nuclear matter...
With the repeated detection of gravitational waves by LIGO, new frontiers in astrophysics and gravitational physics are waiting to be explored. The work we present is dedicated to the theoretical description of ultra compact objects, more recently also called exotic compact objects (ECOs). Using analytic and semi-analytic techniques we focus on gravitational perturbations, where the associated...
Neutron stars accreting matter via an accretion disk offer a unique way to examine the interaction of radiation and matter under extreme conditions. If the neutron star has an ultra-strong magnetic field, the disk is truncated at the so-called magnetospheric radius and matter is guided onto the neutron star surface where its energy is released in X-rays (so-called X-ray pulsars). The...
Binary neutron star mergers are now thought to be a main source of r-process nucleosynthesis, by which most of the heavy elements in our universe have been produced. Furthermore, such systems also constitute a prime candidate for the formation of short gamma ray bursts, which can serve as important electromagnetic counterparts to future gravitational wave detections of such systems.
Using a...
Geometrically thick tori with constant specific angular momentum have been widely used in the last decades to construct numerical models of accretion flows onto black holes. Such discs are prone to a global non-axisymmetric hydrodynamical instability, known as Papaloizou-Pringle instability (PPI), which can redistribute angular momentum and also lead to an emission of gravitational waves. It...
Uniformly rotating neutron stars have been part of many studies in theoretical astrophysics. While a stability criterium against gravitational collapse to a black hole is well known for this type of star, it is not for differentially rotating neutron stars, which are thought to be the outcome of binary neutron star mergers. The stability of the merger remnant has important implications on the...
Spectroscopic analysis of the radiation of binary stellar systems, which contain a neutron star or a black hole, is still among the most topical areas of relativistic high energy astrophysics. The strong dependence of the spectral profiles on the configuration of the source-observer system suggests that the spectral profiles can carry substantial information about the compact object and its...
