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Session 100 - Pulsars & X-ray Binaries.
Oral session, Friday, January 09
Monroe,
We report simultaneous X-ray and infrared (IR) observations of the Galactic microquasar GRS1915+105 using XTE and the Palomar 200-inch telescope on August 13-15, 1997 UTC. During the last two nights, GRS 1915+105 exhibited quasi- regular X-ray/infrared (IR) flares with a spacing of \sim 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 IR 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 IR flare. The common rise and subsequent decoupling of the X-ray and IR flux is consistent with a scenario wherein the IR flux is produced via synchrotron emission from a relativistic plasma which has been ejected from the inner disk. In that case, these simultaneous X-ray/IR flares from a black-hole/ relativistic-jet system are the first clear observational evidence linking a jet to the inner disk in decades of quasar and microquasar studies.
