On the source of quasi-periodic oscillations of the black hole candidate GRS 1915+105: some new observations and their interpretation

A few classes of the light curve of the black hole candidate GRS 1915 + 105 have been analysed in detail. We discover that unlike the previous finding s, quasi-periodic oscillations (QPOs) occasionally occur even in the so-cal led 'On' or softer states. Such findings may require a revision of the accr etion/wind scenario of the black hole candidates. We conjecture that consid erable winds that are produced in 'Off' states cool down as a result of Com ptonization and fall back to the disc, creating an excess accretion rate an d producing the so-called 'On' state. After the drainage of the excess matt er, the disc goes back to the 'Off' state. Our findings strengthen the shoc k oscillation model for QPOs.