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

TL;DR

This paper introduces a shock wave mechanism in accretion disks around black holes that can generate low-frequency QPOs, aligning well with observed phenomena in X-ray binaries and AGNs.

Contribution

It demonstrates that spiral shock waves caused by perturbations in accretion disks can explain low-frequency QPOs, highlighting the role of perturbation velocity over black hole spin or EGB constant.

Findings

Spiral shock waves are linked to QPO generation.

QPO frequencies depend more on perturbation velocity than on black hole spin or EGB constant.

The shock mechanism explains observed QPOs in X-ray binaries and AGNs.

Abstract

We propose a mechanism to explain the low-frequency QPOs observed in X-ray binary systems and AGNs. To achieve this, we perturbed stable accretion disks around Kerr and EGB black holes at different angular velocities, revealing characteristics of shock waves and oscillations on the disk. By applying this perturbation to scenarios with varying alpha values for EGB black holes and different spin parameters for Kerr black holes, we numerically observed changes in the disk dynamic structure and its oscillations. Through various numerical models, we found that the formation of one- and two-armed spiral shock waves on the disk serves as a mechanism for generating QPOs. We compared the QPOs obtained from numerical calculations with the low-frequency QPOs observed in $X$-ray binary systems and AGN sources, finding high consistency with observations. We observed that the shock mechanism, leading to QPOs, explains the X-ray binaries and AGNs studied in this article. Our numerical findings indicate that QPOs are more strongly dependent on the EGB constant than on the black hole spin parameter. However, we highlighted that the primary impact on oscillations and QPOs is driven by the perturbation angular velocity. The results from the models showed that the perturbation asymptotic speed at V_{\infty}=0.2 independently generates QPO frequencies, regardless of the black hole spin parameter and the EGB coupling constant. Therefore, for the moderate value of V_{\infty}, a two-armed spiral shock wave formed around the black hole is suggested as a decisive mechanism in explaining low-frequency QPOs.