arXiv subjects

O. E. Nicotra

Publications and source records attributed to O. E. Nicotra.

6 recordsLinked to original sources

arXiv2007

Hybrid protoneutron stars within a static approach

We study the hadron-quark phase transition in the interior of protoneutron stars. For the hadronic sector, we use a microscopic equation of state involving nucleons and hyperons derived within the finite-temperature Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ the MIT bag model both with a constant and a density-dependent bag parameter. We calculate the structure of protostars within a static approach. In particular we focus on a suitable temperature profile, suggested by dynamical calculations, which plays a fundamental role in determining the value of the minimum gravitational mass. The maximum mass instead depends only upon the equation of state employed.

astro-ph↗

arXiv2006

A microscopic equation of state for protoneutron stars

We study the structure of protoneutron stars within the finite temperature Brueckner-Bethe-Goldstone many-body theory. If nucleons, hyperons, and leptons are present in the stellar core, we find that neutrino trapping stiffens considerably the equation of state, because hyperon onsets are shifted to larger baryon density. However, the value of the critical mass turns out to be smaller than the ``canonical'' value 1.44 $M_\odot$. We find that the inclusion of a hadron-quark phase transition increases the critical mass and stabilizes it at about 1.5--1.6 $M_\odot$.

astro-ph↗

arXiv2006

Structure of protoneutron stars within a static approach

To investigate the stability of the protoneutron stars in their early evolution, the minimum gravitational mass plays a fundamental role. This quantity depends upon the temperature profile assumed. We study within a static approach the stability of a protoneutron star. In particular we focus on a suitable temperature profile suggested by dynamical calculations. We consider a protoneutron star as composed of an isothermal core and an isentropic outer part. To describe physical properties of the interior we employ a microscopically derived equation of state for nuclear matter. For the outer part we employ the Lattimer-Swesty equation of state. The global structure is studied. The assumed temperature profile turns out to give a range of stability which supports temperature values in line with those coming from dynamical calculations. The maximum mass instead depends only upon the equation of state employed.

nucl-th↗

arXiv2006

Hybrid protoneutron stars with the MIT bag model

We study the hadron-quark phase transition in the interior of protoneutron stars. For the hadronic sector, we use a microscopic equation of state involving nucleons and hyperons derived within the finite-temperature Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ the MIT bag model both with a constant and a density-dependent bag parameter. We calculate the structure of protostars with the equation of state comprising both phases and find maximum masses below 1.6 solar masses. Metastable heavy hybrid protostars are not found.

astro-ph↗

arXiv2005

Protoneutron stars within the Brueckner-Bethe-Goldstone theory

We study the structure of newly born neutron stars (protoneutron stars) within the finite temperature Brueckner-Bethe-Goldstone theoretical approach including also hyperons. We find that for purely nucleonic stars both finite temperature and neutrino trapping reduce the value of the maximum mass. For hyperonic stars the effect is reversed, because neutrino trapping shifts the appearance of hyperons to larger baryon density and stiffens considerably the equation of state.

nucl-th↗

arXiv2004

Limiting temperature from microscopic equation of state

The limiting temperature $T_{lim}$ of a series of nuclei is calculated employing a set of microscopic nuclear Equations of State (EoS). It is shown that the value of $T_{lim}$ is sensitive to the nuclear matter Equation of State used. Comparison with the values extracted in recent phenomenological analysis appears to favour a definite selection of EoS' s. On the basis of this phenomenological analysis, it seems therefore possible to check the microscopic calculations of the nuclear EoS at finite temperature, which is hardly accessible through other experimental informations.

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