Quark stars under strong magnetic fields

TL;DR

This paper investigates how strong magnetic fields and their orientations affect the properties and maximum mass of quark stars, revealing that magnetic field direction significantly influences stellar characteristics.

Contribution

It introduces a self-consistent model for the equation of state of magnetized strange quark matter considering magnetic field orientation effects.

Findings

Magnetic field orientation impacts the maximum mass of quark stars.

Radial magnetic fields decrease the maximum mass.

Transverse magnetic fields increase the maximum mass.

Abstract

Within the confined isospin- and density-dependent mass model, we study the properties of strange quark matter (SQM) and quark stars (QSs) under strong magnetic fields. The equation of state of SQM under a constant magnetic field is obtained self-consistently and the pressure perpendicular to the magnetic field is shown to be larger than that parallel to the magnetic field, implying that the properties of magnetized QSs generally depend on both the strength and the orientation of the magnetic fields distributed inside the stars. Using a density-dependent magnetic field profile which is introduced to mimic the magnetic field strength distribution in a star, we study the properties of static spherical QSs by assuming two extreme cases for the magnetic field orientation in the stars, i.e., the radial orientation in which the local magnetic fields are along the radial direction and the transverse orientation in which the local magnetic fields are randomly oriented but perpendicular to the radial direction. Our results indicate that including the magnetic fields with radial (transverse) orientation can significantly decrease (increase) the maximum mass of QSs, demonstrating the importance of the magnetic field orientation inside the magnetized compact stars.