Flux Modulation from the Rossby Wave Instability in microquasars accretion disks: toward a HFQPO model

TL;DR

This study demonstrates that the Rossby wave instability at the inner edge of microquasar accretion disks can modulate flux in a way consistent with observed high-frequency quasi-periodic oscillations, using 3D hydrodynamical modeling.

Contribution

The paper shows that 3D hydrodynamical simulations of Rossby wave instability can reproduce observed flux modulations in microquasars, supporting it as a potential HFQPO model.

Findings

Rossby wave instability modulates flux within observed limits

2D simulations replicate key features of 3D light curves

Current observational resolution cannot distinguish 3D from 2D effects

Abstract

Context. There have been a long string of efforts to understand the source of the variability observed in microquasars, especially concerning the elusive High-Frequency Quasi-Periodic Oscillation. These oscillations are among the fastest phenomena that affect matter in the vicinity of stellar black holes and therefore could be used as probes of strong-field general relativity. Nevertheless, no model has yet gained wide acceptance. Aims. The aim of this article is to investigate the model derived from the occurrence of the Rossby wave instability at the inner edge of the accretion disk. In particular, our goal here is to demonstrate the capacity of this instability to modulate the observed flux in agreement with the observed results. Methods. We use the AMRVAC hydrodynamical code to model the instability in a 3D optically thin disk. The GYOTO ray-tracing code is then used to compute the associated light curve. Results. We show that the 3D Rossby wave instability is able to modulate the flux well within the observed limits.We highlight that 2D simulations allow us to obtain the same general characteristics of the light curve as 3D calculations. With the time resolution we adopted in this work, three dimensional simulations do not give rise to any new observable features that could be detected by current instrumentation or archive data.