The X-Ray Absorption Spectra of Massive X-Ray Binaries
Abstract
Spectral variations in EXOSAT spectra from high mass X-ray binaries are discussed. An observation of the 4U1700-37/HD153919 system of almost one complete binary cycle of 3.41 days showed a sharp increase in absorption at binary phase 0.6. This increase can be modeled as due to a gas stream from the primary trailing the neutron star. The EXOSAT observations of Vela X-1 (4U0900-40/HD 77581) reveal sharp changes in the absorbing column density on top of a more gradual increase between eclipse egress and ingress of the X-ray source. The higher absorption after superior conjunction of the X-ray source indicates the presence of a dense gas stream similar to the one in the 4U1700-37/HD 153919 system. Spectra from 4U1700-37 taken near the peak intensity of flares around phase 0.5 and spectra from Vela X-1 at early orbital phase show an excess of NH at energies lower than 3 keV over that expected from a cold absorber. This excess can be modeled with absorption by ionized gas around the X-rays source. A much larger low energy excess is present at later phases where the NH is higher and can be explained by scattered X-rays.
- Publication:
-
Two Topics in X-Ray Astronomy, Volume 1: X Ray Binaries. Volume 2: AGN and the X Ray Background
- Pub Date:
- November 1989
- Bibcode:
- 1989ESASP.296...31H
- Keywords:
-
- Spectrum Analysis;
- Stellar Spectra;
- Stellar Winds;
- X Ray Absorption;
- X Ray Binaries;
- X Ray Spectra;
- European Space Programs;
- Exosat Satellite;
- Interstellar Gas;
- Stellar Flares;
- Astronomy