Disc-corona interaction in the heartbeat state of GRS 1915+105

TL;DR

This study investigates the disc-corona interaction in GRS 1915+105 during its heartbeat state by applying new timing analysis methods to X-ray data, revealing insights into the origin of variability and the corona's role.

Contribution

The paper introduces novel analysis of phase lag as a function of energy and frequency, providing new details on disc-corona interaction in black hole binaries.

Findings

Phase lag analysis reveals detailed disc-corona interaction features.

Amplitude-ratio spectrum suggests QPO originates from the corona.

New methods improve understanding of variability formation regions.

Abstract

Timing analysis provides information about the dynamics of matter accreting on to neutron stars and black holes, and hence is crucial for studying the physics of the accretion flow around these objects. It is difficult, however, to associate the different variability components with each of the spectral components of the accretion flow. We apply several new methods to two Rossi X-ray Timing Explorer observations of the black hole binary GRS 1915+105 during its heartbeat state to explore the origin of the X-ray variability and the interactions of the accretion-flow components. We offer a promising window into the disc--corona interaction through analysing the formation regions of the disc aperiodic variabilities with different time-scales via comparing the corresponding transition energies of the amplitude-ratio spectra. In a previous paper, we analysed the Fourier power density as a function of energy and frequency to study the origin of the aperiodic variability, and combined that analysis with the phase lag as a function of frequency to derive a picture of the disc--corona interaction in this source. We here, for the first time, investigate the phase lag as a function of energy and frequency, and display some interesting details of the disc--corona interaction. Besides, the results from the shape of amplitude-ratio spectrum and from several other aspects suggest that the quasi-periodic oscillation originates from the corona.