Evidence for a Disk-Jet Interaction in the Microquasar GRS 1915+105

Abstract

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, the microquasar 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. Furthermore, observations of similar IR and radio flares by Fender et al. (1997) 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 IR emission is consistent with a scenario wherein the IR flux originates in a relativistic plasma which 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 linking of the time-dependent interaction of the jet and the inner disk in decades of quasar and microquasar studies.Comment: 15 pages, incl. 3 figures. To appear in ApJ Letter

GRS 1915+105 “celebrates its majority” (1992–2010)

“…Multi-wavelength observations revealed the probable synchrotron origin of the IR emission (Fender & Pooley 1998, MNRAS 300, 576), and this was consistent with a scenario wherein the IR flux originates in a relativistic plasma that has been ejected from the inner accretion disk (Eikenberry et al 1998, Mirabel et al 1998. Analysis of 165 RXTE observations allowed the observations to be classified into 12 classes, which could be ascribed to 3 basic states: a hard state corresponding to the non-observability of the innermost parts of the accretion disk, and two softer states with a fully observable disk (Belloni et al 2000).…”

Identification of the donor in the X-ray binary GRS 1915+105

“…In particular, Eikenberry et al (1998) found variations in line flux of 5 on 5-10 min timescales, suggesting that these IR lines are radiatively pumped by (presumably) jet ejection events rather than high X-ray luminosity. Based on the IR spectral variability and on its position on the IR H-R diagram, Castro-Tirado et al (1996) GRS 1915+105 is a LMXB.…”

Discovery of a Second High-Frequency Quasi-periodic Oscillation from the Microquasar GRS 1915+105

“…GRS 1915ϩ105 exhibits a broad range of correlated multiwavelength variability, including very complex Xray behavior (see, e.g., Muno, Morgan, & Remillard 1999;Markwardt et al 1999;Lin et al 2000), superluminal radio outflows (Mirabel & Rodriguez 1994;Fender & Pooley 2000), and correlated infrared, X-ray, and radio variability (Fender et al 1997;Eikenberry et al 1998;Bandyopadhyay et al 1998). Motivated by the discovery of a second high-frequency QPO in GRO J1655Ϫ40, we analyzed the archival RXTE data from GRS 1915ϩ105 to search for a second QPO in this object as well.…”