Evolution of the Accretion Flow in Nova Muscae 1991

We identify the X-ray-reflected component in the Ginga spectra of Nova Muscae 1991, a black hole transient system used as the prototype for the recent model of Esin, McClintock, & Narayan based on advection-dominated disk solutions. We see that the reflected spectrum is generally significantly relativistically smeared and use this, together with the amplitude of reflection, to track the innermost extent of the accretion disk. The optically thick disk switches from being highly ionized to nearly neutral during the transition from high to low state, and the inner radius of the disk moves outward during the low-state decline. Qualitatively, this overall trend is compatible with the Esin et al. model, but quantitatively, the retreat of the inner disk during the high- to low-state transition is much slower than predicted. The hard (low-state) spectra are not produced solely by an optically thin accretion flow: optically thick material within ~20-100Rg is generally present.

[1]  R. Narayan,et al.  Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991 , 1997, astro-ph/9705237.

[2]  C. Reynolds,et al.  Iron Fluorescence from within the Innermost Stable Orbit of Black Hole Accretion Disks , 1997, astro-ph/9705136.

[3]  M. Begelman,et al.  Self-consistent Thermal Accretion Disk Corona Models for Compact Objects. I. Properties of the Corona and the Spectrum of Escaping Radiation , 1997, The Astrophysical Journal.

[4]  M. Gierliński,et al.  Simultaneous X-ray and 7-ray observations of Cyg X-1 in the hard state by Ginga and OSSE , 1996, astro-ph/9610156.

[5]  Yasuo Tanaka,et al.  X-ray novae , 1996 .

[6]  J. Orosz,et al.  Improved Parameters for the Black Hole Binary System X-Ray Nova MUSCAE 1991 , 1996 .

[7]  N. White,et al.  ASCA Observations of the Iron Line Structure in Cygnus X-1 , 1996 .

[8]  W. Brandt,et al.  X-ray reflection in Galactic black hold candidates: smeared edge profiles and resonant Auger destruction , 1995, astro-ph/9510022.

[9]  Ramesh Narayan,et al.  A New Model for Black Hole Soft X-Ray Transients in Quiescence , 1995, astro-ph/9508014.

[10]  A. Zdziarski,et al.  Angle-dependent Compton reflection of X-rays and gamma-rays , 1995 .

[11]  R. Narayan,et al.  Unified description of accretion flows around black holes , 1995, astro-ph/9502015.

[12]  Lev Titarchuk,et al.  GENERALIZED COMPTONIZATION MODELS AND APPLICATION TO THE RECENT HIGH-ENERGY OBSERVATIONS , 1994 .

[13]  G. Ghisellini,et al.  A MODEL FOR THE X-RAY AND ULTRAVIOLET EMISSION FROM SEYFERT GALAXIES AND GALACTIC BLACK HOLES , 1994, astro-ph/9405059.

[14]  B. Czerny,et al.  The iron ${\rm K}\alpha$ line from a partially ionized reflecting medium in an active galactic nucleus , 1994 .

[15]  A. Fabian,et al.  The effects of photoionization on X-ray reflection spectra in active galactic nuclei , 1993 .

[16]  Keith A. Arnaud,et al.  An ionized accretion disk in Cygnus X-1 , 1992 .

[17]  A. Laor.  Line Profiles from a Disk around a Rotating Black Hole , 1991 .

[18]  Nicholas E. White,et al.  X-ray fluorescence from the inner disc in Cygnus X-1 , 1989 .