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

Abstract

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