HEATING IN AN EXTENDED ACCRETION DISK CORONA ALONG THE Z-PATTERN IN CYG X-2
Author(s)Schulz, Norbert S.; Huenemoerder, David P.; Ji, Li; Yao, Y.; Canizares, Claude R.
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We observed at very high spectral resolution the prototype Z-source Cyg X-2 twice along its entire X-ray spectral variation pattern. In this preliminary analysis, we find an extended accretion disk corona (ADC) exhibiting Lyα emissions from various H-like ions, as well as emissions from He-like ions of Fe and Al, and Be-like ions of Fe. The brightest lines show a range of line broadening: H-like lines are very broad with Doppler velocities between 1100 and 2700 km s[superscript –1], while some others are narrower with widths of a few hundred km s[superscript –1]. Line diagnostics allow us for the first time to determine coronal parameters. The line properties are consistent with a stationary, extended up to 1010 cm, dense (1 × 10[superscript 15] cm[superscript –3]), and hot (log ξ > 3; T > 10[superscript 6] K) ADC. We find ongoing heating of the corona along the Z-track and determine that heating luminosities change from about 0.4×L[subscript Edd] on the horizontal to about 1.4 × L[subscript Edd] on the flaring branch.
DepartmentKavli Institute for Astrophysics and Space Research
American Astronomical Society
"Heating in an Extended Accretion Disk Corona Along the Z-Pattern in Cyg X-2." N. S. Schulz, D. P. Huenemoerder, L. Ji, M. Nowak, Y. Yao, and C. R. Canizares 2009 ApJ 692 L80-L83 doi: 10.1088/0004-637X/692/2/L80 (C)2009 The American Astronomical Society
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