A variable corona for GRS 1915+105

ABSTRACT Most models of the low-frequency quasi-periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs) explain dynamical properties those QPOs. On other hand, recent years reverberation that assume a lamp-post geometry have been successful explaining energy-dependent time lags broad-band noise component stellar mass black holes and active galactic nuclei. We recently shown Comptonization can spectral-timing kilo-hertz (kHz) QPOs observed neutron star (NS) LMXBs. It is therefore worth exploring whether same family would be as In this work, we use model to study frequency dependence phase type-C QPO BH LMXB GRS 1915+105. The 1915+105 make transition from hard soft at around 1.8 Hz. Our shows high frequencies large corona ?100–150 Rg covers most accretion disc makes it $100{{\ \rm per\ cent}}$ feedback dominated, thus producing lags. As decreases, gradually shrinks down 3–17 Rg, Hz on becomes inefficient leading discuss how changes affect timing QPO.