Search for scattered X-ray halos around variable sources - The X-ray halo of Cygnus X-1

Abstract

view Abstract Citations (26) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Search for scattered X-ray halos around variable sources : the X-ray halo of Cygnus X-1. Bode, M. F. ; Priedhorsky, W. C. ; Norwell, G. A. ; Evans, A. Abstract The results of a program to search for the presence of halos due to X-ray scattering by interstellar grains in the line-of-sight to variable X-ray sources are reported. As part of this program, four Einstein HRI images of Cyg X-1 were examined. The analysis technique exploits the intrinsic aperiodic variability of this source to map the point response function of the optics. Any scattered halo present will not reflect short-term central source time variability, since such variability is smoothed by differential time delays of order days. Thus, a residual, nonvariable component to the surface brightness distribution (comprising about 12 percent or more of the source flux) is interpreted as a scattered halo. The Cyg X-1 halo is consistent with those of other sources found in previous studies using different techniques. Comparison is also made with a scattering model and, despite uncertainties in source spectrum and distance, reasonable agreement with the observatons is found using a standard interstellar grain model. The potential of X-ray scattering as a probe of the properties of interstellar grains is demonstrated. Publication: The Astrophysical Journal Pub Date: December 1985 DOI: 10.1086/163751 Bibcode: 1985ApJ...299..845B Keywords: Halos; Interstellar Matter; Variable Stars; X Ray Scattering; X Ray Sources; Brightness Distribution; Cygnus Constellation; Data Acquisition; Data Reduction; Stellar Models; Stellar Spectrophotometry; Astrophysics full text sources ADS | data products SIMBAD (1)