Non-linear variability in microquasars in relation with the winds from their accretion disks

TL;DR

This paper models the quasi-periodic outbursts in microquasars like IGR J17091-3624 using accretion disk instability driven by radiation pressure, linking observed variability to non-linear dynamics and disk winds.

Contribution

It provides a quantitative hydrodynamical simulation of microquasar outbursts and links variability patterns to non-linear equations and disk winds, extending the model to multiple sources.

Findings

Correlation between disk outflows and oscillation stabilization

Verification of models with timing and spectral data

Detection of deterministic chaos in lightcurves

Abstract

The microquasar IGR J17091-3624, which is the recently discovered analogue of the well known source GRS 1915+105, exhibits quasi-periodic outbursts, with a period of 5-70 seconds, and regular amplitudes, referred to as "heartbeat state". We argue that these states are plausibly explained by accretion disk instability, driven by the dominant radiation pressure. Using our GLobal Accretion DIsk Simulation hydrodynamical code, we model these outbursts quantitatively. We also find a correlation between the presence of massive outflows launched from the accretion disk and the stabilization of its oscillations. We verify the theoretical predictions with the available timing and spectral observations. Furthermore, we postulate that the underlying non-linear differential equations that govern the evolution of an accretion disk are responsible for the variability pattern of several other microquasars, including XTE J1550-564, GX 339-4, and GRO J1655-40. This is based on the signatures of deterministic chaos in the observed lightcurves of these sources, which we found using the recurrence analysis method. We discuss these results in the frame of the accretion disk instability model.