Holographic Magnetic Star

TL;DR

This paper investigates a warm fermionic AdS star under magnetic fields, analyzing its physical properties and how temperature and magnetic fields influence its mass limit and entropy, with implications for gauge matter thermalization.

Contribution

It provides a detailed analysis of the effects of temperature and magnetic fields on the properties of AdS stars using relativistic Landau levels and TOV equations, offering new insights into holographic thermalization.

Findings

Temperature increases the star's mass limit.

Magnetic field decreases the star's mass limit.

Entropy density shows temperature dependence similar to black branes.

Abstract

A warm fermionic AdS star under a homogeneous magnetic field is explored. We obtain the relativistic Landau levels by using Dirac equation and use the Tolman-Oppenheimer-Volkoff (TOV) equation to study the physical profiles of the star. Bulk properties such as sound speed, adiabatic index, and entropy density within the star are calculated analytically and numerically. Bulk temperature increases the mass limit of the AdS star but external magnetic field has the opposite effect. The results are partially interpreted in terms of the pre-thermalization process of the gauge matter at the AdS boundary after the mass injection. The entropy density is found to demonstrate similar temperature dependence as the magnetic black brane in the AdS in certain limits regardless of the different nature of the bulk and Hawking temperatures. Total entropy of the AdS star is also found to be an increasing function of the bulk temperature and a decreasing function of the magnetic field, similar behaviour to the mass limit. Since both total entropy and mass limit are global quantities, they could provide some hints to the value of entropy and energy of the dual gauge matter before and during the thermalization.