Massive Hybrid Quark Stars with Strong Magnetic Field

TL;DR

This paper investigates the effects of extremely strong magnetic fields on hybrid quark stars, showing that such fields can lead to stable, massive stars with quark matter dominated cores exceeding two solar masses.

Contribution

It introduces a model of hybrid stars with magnetic fields around 10^{19} Gauss, demonstrating the possibility of stable, massive quark-dominated hybrid stars.

Findings

Magnetic fields of order 10^{19} Gauss influence quark matter properties.

Pressure in the lowest Landau level is a function of energy density, respecting causality.

Hybrid stars with large quark cores can exceed two solar masses.

Abstract

We estimate the critical magnetic field strength at which the lowest or second Landau levels play an important role in the quark phase inside the hybrid stars, and show that the magnetic field should be in the order of $10^{19}$ Gauss at the nuclear density $\sim0.16$ fm$^{-3}$. We also find that the pressure of quark matter settling only in the lowest Landau level can be expressed as a function of the energy density independently of the magnetic field strength, which corresponds to the causality limit of a stiff equation of state. Adiabatic index of quark matter well exceeds 4/3 in the core, and we find a possibility to construct massive hybrid star models occupied in large part by quark matter, whose maximum mass becomes larger than two solar mass.