Neutron stars models in 4D Einstein-Gauss-Bonnet gravity.
Loading...
Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
El estudio de objetos compactos en teorías modificadas de la gravedad expande nuestra descripción de la física gravitacional más allá de la Relatividad General (RG). En particular, las estrellas de neutrones son objetos con altas densidades y fuertes campos gravitacionales, lo que las convierte en laboratorios ideales para testear los límites de la teoría de Einstein en condiciones extremas. En esta tesis, encontramos soluciones numéricas de estrellas de neutrones en gravedad 4D Einstein-Gauss-Bonnet (4DEGB) usando ecuaciones de estado (EdEs) realistas para describir todas las regiones en el interior de una estrella de neutrones. En particular, usamos la EdE SLy (Skyrme Lyon) y MS2 (Müller and Serot), previamente utilizadas por Charmousis et al. (2022), en conjunto con la familia de EdEsBSk(Brussels-Montreal Skyrme functionales), la cual incorpora refinamientos a la EdE SLy para mejorar el ajuste tanto a las propiedades de la materia nuclear como a las observaciones de estrellas de neutrones. Con el fin de proporcionar las condiciones necesarias para la existencia de dichas soluciones, analizamos la estabilidad de las mismas a través de perturbaciones radiales adiabáticas. Encontramos que el cambio de estabilidad ocurre en la configuración de masa máxima, como en RG, obteniendo estrellas de neutrones estables con masas más grandes comparadas con las de la teoría de Einstein. Además, la brecha de masa entre las estrellas de neutrones y los agujeros negros de los mismos radios se reduce a medida que aumentamos la constante de acoplamiento de la teoría 4DEGB. La reducción de esta brecha de masa indica que algunos objetos astrofísicos (dentro de esta teoría) podrían ser estrellas de neutrones masivas u objetos más exóticos en lugar de agujeros negros. Nuestros hallazgos ofrecen valiosas contribuciones a la comprensión de los objetos compactos en el marco de la gravedad 4DEGB.
The study of compact objects in modified theories of gravity expands our description of gravitational physics beyond General Relativity (GR). In particular, neutron stars (NS) are objects with high densities and strong gravitational fields, establishing them as ideal laboratories to test the limits of Einstein’s theory under extreme conditions. In this thesis, we find numerical solutions of NS in 4D Einstein-Gauss-Bonnet (4DEGB) gravity using realistic equations of state (EOSs) to describe all regions inside a NS. In particular, we employ the SLy (Skyrme Lyon) and MS2 (Müller and Serot) EOSs, previously used by Charmousis et al. (2022), along with the BSk (Brussels-Montreal Skyrme functionals) family of EOSs, which incorporate refinements to SLy EOS to improve the fit to both nuclear matter properties and neutron star observations. In order to provide necessary conditions for the existence of such solutions, we analyzed the stability of these configurations by adiabatic radial perturbations. We found that the change of stability occurs at the maximum mass configuration, as in GR, obtaining stable neutron stars with greater mass compared to neutron stars in Einstein’s theory. In addition, the mass gap between neutron stars and black holes of the same radii is reduced as we increase the coupling constant of the 4DEGB theory. The reduction of this mass gap indicates that some astrophysical objects (within this theory) could be massive neutrons stars or more exotic objects instead of black holes. Our findings offer valuable contributions to the understanding of compact objects within the framework of 4DEGB gravity.
The study of compact objects in modified theories of gravity expands our description of gravitational physics beyond General Relativity (GR). In particular, neutron stars (NS) are objects with high densities and strong gravitational fields, establishing them as ideal laboratories to test the limits of Einstein’s theory under extreme conditions. In this thesis, we find numerical solutions of NS in 4D Einstein-Gauss-Bonnet (4DEGB) gravity using realistic equations of state (EOSs) to describe all regions inside a NS. In particular, we employ the SLy (Skyrme Lyon) and MS2 (Müller and Serot) EOSs, previously used by Charmousis et al. (2022), along with the BSk (Brussels-Montreal Skyrme functionals) family of EOSs, which incorporate refinements to SLy EOS to improve the fit to both nuclear matter properties and neutron star observations. In order to provide necessary conditions for the existence of such solutions, we analyzed the stability of these configurations by adiabatic radial perturbations. We found that the change of stability occurs at the maximum mass configuration, as in GR, obtaining stable neutron stars with greater mass compared to neutron stars in Einstein’s theory. In addition, the mass gap between neutron stars and black holes of the same radii is reduced as we increase the coupling constant of the 4DEGB theory. The reduction of this mass gap indicates that some astrophysical objects (within this theory) could be massive neutrons stars or more exotic objects instead of black holes. Our findings offer valuable contributions to the understanding of compact objects within the framework of 4DEGB gravity.
Description
Tesis presentada para optar al grado académico de Magíster en Ciencias con Mención en Física
Keywords
Relatividad generalizada (Física), Estrellas de neutrones, Astrofísica