Anisotropic pressure in the quark core of a strongly magnetized hybrid star

TL;DR

This paper investigates how strong, density-dependent magnetic fields affect the thermodynamic properties and stability of strange quark matter in the core of magnetized hybrid stars, revealing an upper magnetic field limit for stability.

Contribution

It introduces a density-dependent magnetic field model and analyzes its effects on pressure anisotropy and stability limits in quark matter within hybrid stars.

Findings

Identified an upper magnetic field bound for stable quark matter.

Derived expressions for energy density and pressures as functions of baryon density.

Demonstrated the development of instability beyond the magnetic field upper bound.

Abstract

The impact of a strong magnetic field, varying with the total baryon number density, on thermodynamic properties of strange quark matter (SQM) in the core of a magnetized hybrid star is considered at zero temperature within the framework of the Massachusetts Institute of Technology (MIT) bag model. It is clarified that the central magnetic field strength is bound from above by the value at which the derivative of the longitudinal pressure with respect to the baryon number density vanishes first somewhere in the quark core under varying the central field. Above this upper bound, the instability along the magnetic field is developed in magnetized SQM. The total energy density, longitudinal and transverse pressures are found as functions of the total baryon number density.