Anti-Correlation of Near-Infrared and X-Ray Variations of the Microquasar GRS 1915 105 in the Soft State

作者:Arai Akira*; Uemura Makoto; Sasada Mahito; Trushkin Sergei A; Ueda Yoshihiro; Takahashi Hiromitsu; Kawabata Koji S; Yamanaka Masayuki; Nagae Osamu; Ikejiri Yuki; Sakimoto Kiyoshi; Matsui Risako; Ohsugi Takashi; Yamashita Takuya; Isogai Mizuki; Fukazawa Yasushi; Mizuno Tsunefumi; Katagiri Hideaki; Okita Kiichi; Yoshida Michitoshi; Yanagisawa Kenshi; Sato Shuji; Kino Masaru; Sadakane Kozo
来源:Publications of the Astronomical Society of Japan, 2009, 61(3): L1-L5.
DOI:10.1093/pasj/61.3.l1

摘要

We present detailed, long term near-infrared (NIR) light curves of GRS 1915 105 obtained in 2007-2008, covering its long "soft state" for the first time. From our NIR monitoring and X-ray data of the All Sky Monitor onboard Rossi X-ray Timing Explorer, we discovered that the NIR flux dropped by > 1 mag during short X-ray flares with a time-scale of days. Upon termination of the soft state, the H - K(s) color reddened and the anti-correlation pattern was broken. The observed H - K(s) color variation suggests that the dominant NIR source was an accretion disk during the soft state. The short X-ray flares during the soft state were associated with spectral hardening in X-rays and increasing radio emission, indicating jet ejection. The temporal NIR fading during the X-ray flares thus implies a sudden decrease in the contribution of the accretion disk when a jet is ejected.