Accreting strongly magnetised neutron stars: X-ray Pulsars

TL;DR

This paper reviews recent observational and theoretical progress on X-ray pulsars, strongly magnetized neutron stars in binary systems, highlighting their role as laboratories for studying physics under extreme magnetic and plasma conditions.

Contribution

It provides a comprehensive overview of recent advances in understanding the physics of X-ray pulsars, emphasizing their importance for fundamental physics research.

Findings

Enhanced understanding of magnetic field effects on neutron star emissions

Insights into plasma and radiative processes in ultra-strong magnetic fields

Identification of open questions in neutron star physics

Abstract

X-ray pulsars (XRPs) are accreting strongly magnetised neutron stars (NSs) in binary systems with, as a rule, massive optical companions. Very reach phenomenology and high observed flux put them into the focus of observational and theoretical studies since the first X-ray instruments were launched into space. The main attracting characteristic of NSs in this kind of system is the magnetic field strength at their surface, about or even higher than $10^{12}\,{\rm G}$, that is about six orders of magnitude stronger than what is attainable in terrestrial laboratories. Although accreting XRPs were discovered about 50 years ago, the details of the physical mechanisms responsible for their properties are still under debate. Here we review recent progress in observational and theoretical investigations of XRPs as a unique laboratory for studies of fundamental physics (plasma physics, QED and radiative processes) under extreme conditions of ultra-strong magnetic field, high temperature, and enormous mass density.