The Study of Black Hole Properties from Variability of X-ray Emission in Galactic Black Hole X-ray Binaries

Abstract

In this study, we investigate the properties of five Galactic Black Hole X-ray Binaries (BHXBs): GRO J1655-40, GX 339-4, XTE J1650-500, XTE J1550-564, and XTE J1118+480, focusing on estimating their black hole masses and spins through X-ray variability analysis. We utilize X-ray light curve data from the All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE), specifically within the 2-10 keV energy range. We identify and characterize Quasi Periodic Oscillations (QPOs) in the X-ray light curves of these BHXBs and apply theoretical models to estimate black hole masses and spins. For these analyses, we used two primary theoretical models the Resonance model and the Lense-Thirring Precession model. Through fitting these models to the observed QPO frequencies, we derive mass and spin estimates for each BHXB candidate. The results reveal a diverse range of black hole masses, from approximately 5.92 ± 0.60 M⊙ to 10.02 ± 0.12 M⊙. This estimated mass range suggests that these black holes fall within the category of stellar-mass black holes. The GRO J1655-40 and XTE J1118+480 exhibit moderate to low spin values, implying less active accretion processes, while GX 339-4, XTE J1650-500, and XTE J1550-564 show higher spin parameters, indicating a stronger influence of relativistic effects.The consistency of mass estimates derived from both models with each other and with values from prior studies affirms the robustness of the methods used. This study concludes that analyzing X-ray variability, particularly through QPO characterization, provides a powerful tool for investigating the fundamental properties of black holes within BHXB systems.