Observational evidence for mass ejection during soft X-ray dips in GRS 1915+105

¹ Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai (Bombay) 400 005, India
² S.N. Bose National Center for Basic Sciences, Salt Lake, Calcutta 700 091, India

Corresponding author: S. V. Vadawale, santoshv@tifr.res.in

Received: 8 January 2001
Accepted: 1 March 2001

Abstract

We investigate the connection between the X-ray and radio properties of the Galactic microquasar GRS 1915+105, by analyzing the X-ray data observed with RXTE, during the presence of a huge radio flare (~450 mJy). The X-ray lightcurve shows two dips of ~100 s duration. Detailed time resolved spectral analysis shows the existence of three spectral components: a multicolor disk-blackbody, a Comptonized component due to hot plasma and a power-law. We find that the Comptonized component is very weak during the dip. This is further confirmed by the PHA ratio of the raw data and ratio of the lightcurves in different energy bands. These results, combined with the fact that the 0.5-10 Hz QPO disappears during the dip and that the Comptonized component is responsible for the QPO lead to the conclusion that during the dips the matter emitting Comptonized spectrum is ejected away. This establishes a direct connection between the X-ray and radio properties of the source.