Fermion Proca Stars: Vector Dark Matter Admixed Neutron Stars

Fuente: arXiv
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Autori principali: Jockel, Cédric, Sagunski, Laura
Natura: Preprint
Pubblicazione: 2023
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author Jockel, Cédric
Sagunski, Laura
author_facet Jockel, Cédric
Sagunski, Laura
contents Dark matter could accumulate around neutron stars in sufficient amounts to affect their global properties. In this work, we study the effect of a specific model for dark matter -- a massive and self-interacting vector (spin-1) field -- on neutron stars. We describe the combined systems of neutron stars and vector dark matter using Einstein-Proca theory coupled to a nuclear-matter term, and find scaling relations between the field and metric components in the equations of motion. We construct equilibrium solutions of the combined systems, compute their masses and radii and also analyse their stability and higher modes. The combined systems admit dark matter (DM) core and cloud solutions. Core solutions compactify the neutron star component and tend to decrease the total mass of the combined system. Cloud solutions have the inverse effect. Electromagnetic observations of certain cloud-like configurations would appear to violate the Buchdahl limit. This could make Buchdahl-limit violating objects smoking gun signals for dark matter in neutron stars. The self-interaction strength is found to significantly affect both mass and radius. We also compare fermion Proca stars to objects where the dark matter is modelled using a complex scalar field. We find that fermion Proca stars tend to be more massive and geometrically larger than their scalar field counterparts for equal boson masses and self-interaction strengths. Both systems can produce degenerate masses and radii for different amounts of DM and DM particle masses.
format Preprint
id arxiv_https___arxiv_org_abs_2310_17291
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Fermion Proca Stars: Vector Dark Matter Admixed Neutron Stars
Jockel, Cédric
Sagunski, Laura
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Theory
Dark matter could accumulate around neutron stars in sufficient amounts to affect their global properties. In this work, we study the effect of a specific model for dark matter -- a massive and self-interacting vector (spin-1) field -- on neutron stars. We describe the combined systems of neutron stars and vector dark matter using Einstein-Proca theory coupled to a nuclear-matter term, and find scaling relations between the field and metric components in the equations of motion. We construct equilibrium solutions of the combined systems, compute their masses and radii and also analyse their stability and higher modes. The combined systems admit dark matter (DM) core and cloud solutions. Core solutions compactify the neutron star component and tend to decrease the total mass of the combined system. Cloud solutions have the inverse effect. Electromagnetic observations of certain cloud-like configurations would appear to violate the Buchdahl limit. This could make Buchdahl-limit violating objects smoking gun signals for dark matter in neutron stars. The self-interaction strength is found to significantly affect both mass and radius. We also compare fermion Proca stars to objects where the dark matter is modelled using a complex scalar field. We find that fermion Proca stars tend to be more massive and geometrically larger than their scalar field counterparts for equal boson masses and self-interaction strengths. Both systems can produce degenerate masses and radii for different amounts of DM and DM particle masses.
title Fermion Proca Stars: Vector Dark Matter Admixed Neutron Stars
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2310.17291