Variability of the Halpha emission of Cygnus X-1 and its connection with the soft X-ray radiation

Abstract

High-resolution Halpha monitoring of Cyg X-1, HD226868 was carried out during 1996-2002 and the resultant spectra analysed in conjunction with 1.5-12 keV X-ray monitoring. We demonstrate that the Halpha line-profiles have complex variability on different timescales, controlled in particular by the orbital period and the focused wind model of mass loss. We find that long-term variability of the mass loss by the supergiant and short-term variability due to clumpy structure of the stellar wind dominate during the low/hard X-ray state and that X-ray photoionization has a relatively small influence on the line-profile shape and EW variability. During the high/soft X-ray state and flaring the effect of photoionization the line-profile and EW of Halpha increases but is still unable to describe the loose anti-correlation between EW and the low energy X-ray emission. We propose that variability of the mass loss by the supergiant can change wind velocities in the Stromgren zone around the accretion disc of the secondary, leading to an increase in accretion rate through the disc.

Accepted for publication in A&A

References in corpus (3)

• Understanding the long-term spectral variability of Cygnus X-1 with BATSE and ASM observations
• The First High Resolution X-ray Spectrum of Cyg X-1: Soft X-Ray Ionization and Absorption
• Modelling the orbital modulation of ultraviolet resonance lines in high-mass X-ray binaries

Cited by in corpus (8)

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• Stellar Wind Variations During the X-ray High and Low States of Cygnus X-1
• H-alpha observations of the gamma-ray-emitting Be/X-ray binary LSI+61303: orbital modulation, disk truncation, and long-term variability
• Ultraviolet observations of the X-ray photoionized wind of Cygnus X-1 during X-ray soft/high state
• Optical Spectroscopic Observations of Cyg X-1=HDE 226868
• Comprehensive UV and Optical spectral analysis of Cygnus X-1: Stellar and wind parameters, abundances, and evolutionary implications
• X-ray Variations at the Orbital Period from Cygnus X-1 in the High/Soft State