Realistic Anisotropic Neutron Stars: Pressure Effects

Fuente: arXiv
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Main Authors: Becerra, L. M., Becerra-Vergara, E. A., Lora-Clavijo, F. D.
Format: Preprint
Published: 2024
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author Becerra, L. M.
Becerra-Vergara, E. A.
Lora-Clavijo, F. D.
author_facet Becerra, L. M.
Becerra-Vergara, E. A.
Lora-Clavijo, F. D.
contents In this paper, we study the impact of anisotropy on neutron stars with different equations of state, which have been modeled by a piecewise polytropic function with continuous sound speed. Anisotropic pressure in neutron stars is often attributed to interior magnetic fields, rotation, and the presence of exotic matter or condensates. We quantify the presence of anisotropy within the star by assuming a quasi-local relationship. We find that the radial and tangential sound velocities constrain the range of anisotropy allowed within the star. As expected, the anisotropy affects the macroscopic properties of stars, and it can be introduced to reconcile them with astrophysical observations. For instance, the maximum mass of anisotropic neutron stars can be increased by up to 15\% compared to the maximum mass of the corresponding isotropic configuration. This allows neutron stars to reach masses greater than $2.5M_\odot$, which may explain the secondary compact object of the GW190814 event. Additionally, we propose a universal relation for the binding energy of an anisotropic neutron star as a function of the star's compactness and the degree of anisotropy.
format Preprint
id arxiv_https___arxiv_org_abs_2401_10311
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Realistic Anisotropic Neutron Stars: Pressure Effects
Becerra, L. M.
Becerra-Vergara, E. A.
Lora-Clavijo, F. D.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
General Relativity and Quantum Cosmology
In this paper, we study the impact of anisotropy on neutron stars with different equations of state, which have been modeled by a piecewise polytropic function with continuous sound speed. Anisotropic pressure in neutron stars is often attributed to interior magnetic fields, rotation, and the presence of exotic matter or condensates. We quantify the presence of anisotropy within the star by assuming a quasi-local relationship. We find that the radial and tangential sound velocities constrain the range of anisotropy allowed within the star. As expected, the anisotropy affects the macroscopic properties of stars, and it can be introduced to reconcile them with astrophysical observations. For instance, the maximum mass of anisotropic neutron stars can be increased by up to 15\% compared to the maximum mass of the corresponding isotropic configuration. This allows neutron stars to reach masses greater than $2.5M_\odot$, which may explain the secondary compact object of the GW190814 event. Additionally, we propose a universal relation for the binding energy of an anisotropic neutron star as a function of the star's compactness and the degree of anisotropy.
title Realistic Anisotropic Neutron Stars: Pressure Effects
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2401.10311