X-raying a galaxy: PHL 6625 behind NGC 247
Abstract
PHL 6625, a z=0.38, radio-quiet quasar, shows a clear excess of low-energy absorption in its ROSAT PSPC soft X-ray spectrum. This absorption is almost certainly produced by the interstellar medium in NGC 247, a foreground spiral galaxy, which lies ~3.4 kpc (4.6 arcmin) away in projection. Comparison of the X-ray absorption and the 21-cm H i column density through NGC 247 suggests a larger than expected effect in X-rays. Several possibilities are considered to explain this apparent discrepancy. Additional high-velocity H i components of the interstellar medium are currently the most plausible cause. PHL 6625 also clearly decreased in its soft X-ray flux by a factor of 2 in 6 months.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 1997
- DOI:
- 10.1093/mnras/291.3.L49
- Bibcode:
- 1997MNRAS.291L..49E
- Keywords:
-
- Quasars;
- Active Galactic Nuclei;
- Interstellar Matter;
- X Ray Sources;
- Absorption Spectra;
- X Ray Spectra;
- H I Regions;
- High Speed;
- Astrophysics;
- GALAXIES: ACTIVE;
- GALAXIES: INDIVIDUAL: NGC 247;
- GALAXIES: ISM;
- QUASARS: INDIVIDUAL: PHL 6625;
- X-RAYS: GALAXIES