Wind Accretion and State Transitions in Cygnus X-1

Details Wind Accretion and State Transitions in Cygnus X-1 Wind Accretion and State Transitions in Cygnus X-1

2002-06-14

arxiv.org/abs/astro-ph/0206253v2

Astrophys.J.583:424-436,2003

Astronomy and Astrophysics

Astrophysics

45 pages, 16 figures, ApJ, in press

Scientific paper

10.1086/345345

We present the results of a spectroscopic monitoring program (from 1998 to 2002) of the H-alpha emission strength in HDE 226868, the optical counterpart of the black hole binary, Cyg X-1. The H-alpha profiles consist of (1) a P Cygni component associated with the wind of the supergiant, (2) emission components that attain high velocity at the conjunctions and that probably form in enhanced outflows both towards and away from the black hole, and (3) an emission component that moves in anti-phase with the supergiant's motion. We argue that the third component forms in accreted gas near the black hole, and the radial velocity curve of the emission is consistent with a mass ratio of M_X / M_opt = 0.36 +/- 0.05. We find that there is a general anti-correlation between the H-alpha emission strength and X-ray flux in the sense that when the H-alpha emission is strong (W_\lambda < -0.5 Angstroms) the X-ray flux is weaker and the spectrum harder. On the other hand, there is no correlation between H-alpha emission strength and X-ray flux when H-alpha is weak. During the low/hard X-ray state, the strong wind is fast and the accretion rate is relatively low, while in the high/soft state the weaker, highly ionized wind attains only a moderate velocity and the accretion rate increases. We argue that the X-ray transitions from the normal low/hard to the rare high/soft state are triggered by episodes of decreased mass loss rate in the supergiant donor star.

Affiliated with

Also associated with

No associations

Rating

Wind Accretion and State Transitions in Cygnus X-1 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Wind Accretion and State Transitions in Cygnus X-1, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wind Accretion and State Transitions in Cygnus X-1 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-98788