Probing the Inflow/Outflow and Accretion Disk of Cygnus X-1 in the High State with the Chandra High Energy Transmission Grating

Cygnus X-1 was observed in the high state at the conjunction orbital phase (0) with the Chandra High Energy Transmission Grating (HETG). Strong and asymmetric absorption lines of highly ionized species were detected, such as Fe XXV, Fe XXIV, Fe XXIII, Si XIV, S XVI, Ne X, etc. In the high state the profile of the absorption lines is composed of an extended red wing and a less extended blue wing. The red wings of higher ionized species are more extended than those of lower ionized species. The detection of these lines provides a way to probe the properties of the flow around the companion and the black hole in Cyg X-1 during the high state. A broad emission feature around 6.5 keV was significantly detected from the spectra of both the Chandra/HETG and the RXTE/Proportional Counter Array. This feature appears to be symmetric and can be fitted with a Gaussian function rather than the Laor disk line model of the fluorescent Fe Kα line from an accretion disk. The implications of these results on the structure of the accretion flow of Cyg X-1 in the high state are discussed.