Towards modeling quasi-periodic oscillations of microquasars with oscillating slender tori

TL;DR

This paper develops a model for high-frequency quasi-periodic oscillations in X-ray binaries by analyzing how different periodic deformations of slender accretion tori affect their observable light curves and power spectra.

Contribution

It introduces a method to distinguish deformation types in oscillating tori through their unique spectral signatures, advancing the modeling of QPOs.

Findings

Different deformations produce distinct Fourier power spectra.

Observable signatures can potentially constrain the oscillating torus model.

The approach offers a new way to interpret QPO observations.

Abstract

Context. One of the often discussed models for X-ray binaries high-frequency quasi-periodic oscillations is the oscillating torus model that considers oscillation modes of slender accretion tori. Aims. Here, we aim at developing this model by considering the observable signature of an optically thick slender accretion torus subject to simple periodic deformations. Methods. We compute light curves and power spectra of a slender accretion torus subject to simple periodic deformations: vertical or radial translation, rotation, expansion and shear. Results. We show that different types of deformations lead to very different Fourier power spectra and therefore could be observationally distinguished. Conclusions. This work is a first step in a longer-term study of the observable characteristics of the oscillating torus model. It gives promising perspectives on the possibility to constrain this model by studying the observed power spectra of quasi-periodic oscillations.