Speaker
Description
Be X-ray binaries, which constitute the largest subclass of high-mass X-ray binary systems, consist of a neutron star in an eccentric orbit around a Be star companion, accompanied by a geometrically thin Keplerian disc. These systems are strong candidates for being progenitors of gravitational waves, as their evolutionary process can ultimately lead to the formation of a binary system containing two compact objects (either two neutron stars or a neutron star and a black hole). The interaction between the neutron star and the Be disc results in the accretion of matter, which leads to X-ray outbursts.
These X-ray outbursts occur in two varieties: Type I (normal outbursts, with luminosities less than 10^37 erg/s) and Type II (giant outbursts, with luminosities greater than 10^37 erg/s). The variability of the disc can be traced through the changes in the Balmer emission lines in the optical spectra, with the Hα emission line being the strongest and best studied.
In this presentation, I will share the optical and X-ray analysis of individual outbursting systems monitored with the Southern African Large Telescope (SALT), OGLE, MeerKAT, and X-ray missions such as Swift and MAXI. The aim is to study the impact of the neutron star on the Be disc under various orbital configurations and environmental conditions. I will discuss the interesting long-term behavior of the Balmer lines over multiple orbits of the neutron star and draw conclusions about the structure of the Be disc. Additionally, I will highlight the differences in behavior among the systems and how variations in the orbital parameters affect the evolution of the Be disc and the accretion process, leading to enhanced X-ray emission.