Proposing a Physical Mechanism to Explain Various Observed Sources of QPOs by Simulating the Dynamics of Accretion Disks around the Black Holes

Orhan Donmez

Published 2023-11-14Version 1

We propose a mechanism to explain the low-frequency QPOs observed in X-ray binary systems and AGNs. To do this, we perturbed stable accretion disks around Kerr and EGB black holes at different angular velocities, revealing the characteristics of shock waves and oscillations presented on the disk. Applying this perturbation to scenarios with different alpha values for EGB black holes and different spin parameters for Kerr black holes, we numerically observed changes in the dynamic structure of the disk and oscillations. Through various numerical modeling, we found that the formation of one- and two-armed spiral shock waves on the disk serves as a mechanism for the generation of QPOs. We compared the QPOs obtained from numerical calculations with the low-frequency QPOs observed in $X-$ray binary systems and AGN sources. We found that the results obtained are highly consistent with observations. We observed that the shock mechanism on the disk, which leads to quasi-periodic oscillations, explains the X-ray binaries and AGNs studied in this article. As a result of the numerical findings, we find that QPOs are more strongly dependent on the EGB constant rather than the black hole's spin parameter However, we highlighted that the primary impact on oscillations and QPOs is driven by the perturbation's angular velocity. According to the results obtained from the models, it has been observed that the perturbation's asymptotic speed at V_{\infty}=0.2 is responsible for generating QPO frequencies independently of the black hole's spin parameter and the EGB coupling constant. Therefore, for the moderate value of V_{\infty}, a two-armed spiral shock wave formed on the disk is suggested as a decisive mechanism in explaining low-frequency QPOs.