Evidence for a disk-jet interaction in the microquasar GRS 1915+105

We report simultaneous X-ray and infrared (IR) observations of the Galactic microquasar GRS 1915+105 using the Rossi X-Ray Timing Explorer and the Palomar 5 m telescope on 1997 August 13-15 UTC. During the last two nights, the microquasar GRS 1915+105 exhibited quasi-regular X-ray/IR flares with a spacing of similar to 30 minutes. While the physical mechanism triggering the flares is currently unknown, the one-to-one correspondence and consistent time offset between the X-ray and m flares establish a close link between the two. At late times in the flares, the X-ray and IR bands appear to "decouple," with the X-ray band showing large-amplitude fast oscillations while the IR shows a much smoother, more symmetrical decline. In at least three cases, the IR flare has returned to near its minimum while the X-rays continue in the elevated oscillatory state, ruling out thermal reprocessing of the X-ray flux as the source of the IR flares. Furthermore, observations of similar IR and radio flares by Fender et al. imply that the source of the IR flux in such flares is synchrotron emission. The common rise and subsequent decoupling of the X-ray and IR flux and probable synchrotron origin of the LR emission are consistent with a scenario wherein the TR flux originates in a relativistic plasma that has been ejected from the inner accretion disk. In that case, these simultaneous X-ray/IR flares from a black hole/relativistic jet system are the first clear observational evidence revealing the time-dependent interaction of the jet and the inner disk in decades of quasar and microquasar studies.