Anti-correlated hard X-ray time lag in GRS 1915+105: evidence for a   truncated accretion disc
  Multi-wavelength observations of Galactic black hole candidate sources indicate a close connection between the accretion disk emission and the jet emission. The recent discovery of an anti-correlated time lag between the soft and hard X-rays in Cygnus X-3 (Choudhury & Rao 2004) constrains the geometric picture of the disk-jet connection into a truncated accretion disk, the truncation radius being quite close to the black hole. Here we report the detection of similar anti-correlated time lag in the superluminal jet source GRS 1915+105. We show the existence of the pivoting in the X-ray spectrum during the delayed anti-correlation and we also find that the QPO parameters change along with the spectral pivoting. We explore theoretical models to understand this phenomenon. 
Manojendu Choudhury (National Centre for Radio Astrophysics, T.I.F.R.,   Pune. India), A. R.Rao, Surajit Dasgupta (T.I.F.R.,...