Highlight Sciences on Low Magnetic Field Neutron Stars X-ray Binaries with Insight-HXMT

Abstract

Low magnetic field neutron stars X-ray binaries are the systems where the magnetic field strength of the primary star (neutron star) is less than 10${}^{10}$ Gauss. In these systems, the neutron star undergoes Roche lobe overflow, whereby matter is accreted from its companion star through an accretion disk. During the accretion process, a substantial quantity of gravitational energy is released and transformed into X-ray radiation in the vicinity of the neutron star. The X-ray emissions from these systems typically exhibit rapid temporal variability with short time scales, along with changes in spectral characteristics. These celestial objects are of great significance in fundamental physics, particularly in testing general relativity and strong gravitational field effects, as well as studying the equation of state of ultra-dense matter. This review presents a summary of observational research on weakly magnetic field neutron stars in low-mass X-ray binaries, with a focus on recent advancements in the study of kilohertz quasi-periodic oscillations, hard X-ray tails, and the evolution of the accretion disk-corona geometry along the accretion state, since the launch of the Insight-HXMT (Insight Hard Xray Modulation Telescope) satellite.