On the source of QPO of the black hole candidate GRS1915+105: some new   observations and their interpretation
  A few classes of the light curve of the black hole candidate GRS 1915+105 have been analyzed in detail. We discover that unlike the previous findings, QPOs occasionally occur even in the so-called `On' or softer states. Such findings may require a revision of the accretion/wind scenario of the black hole candidates. We conjecture that considerable winds which is produced in `Off' states, cool down due to Comptonization, and falls back to the disk and creating an excess accretion rate to produce the so-called `On' state. After the drainage of the excess matter, the disk goes back to the `Off' state. Our findings strengthen the shock oscillation model for QPOs. 
Anuj Nandi (SNBNCBS), Sivakumar G. Manickam (SNBNCBS), A.R. Rao (TIFR)   and Sandip K. Chakrabarti (SNBNCBS)