Dr. Aru Beri

Accretion-powered X-ray pulsars provide a unique laboratory for probing extreme magnetic fields and matter under intense gravitational forces. Recent multiwavelength observations of high-mass X-ray binaries and ultra-luminous X-ray pulsars have significantly advanced our understanding of extreme accretion processes and neutron star magnetospheres. This talk will present a comprehensive analysis of the Be/X-ray binary RX J0520.5-6932 during its giant 2024 outburst, the detection of a stable cyclotron resonant scattering feature (CRSF) at ~32 keV and its implications for long-term magnetic field stability. Complementary insights come from the first Galactic ultra-luminous X-ray pulsar, Swift J0243.6+6124, where broadband AstroSat observations reveal significant pulse profile evolution and high-energy emission features across sub- and super-Eddington accretion regimes. Additionally, I will present findings from the 2019 outburst of 4U 1901+03, highlighting the luminosity-dependent evolution of pulse profiles and discovery of a CRSF at ~30 keV, shedding light on the neutron star’s magnetic field and accretion geometry. Finally, I will underscore the need for broadband X-ray polarization studies to probe the orientation of the magnetic and rotational axes, offering critical insights into the geometry and physics of accretion columns and magnetosphere beaming patterns.