X-ray observations of M33 with the high resolution imager on the Einstein Observatory
Abstract
Three observations, separated by 6 months, of the Local Group galaxy M33 using the high resolution imager (HRI) on the Einstein Observatory are reported. Eight X-ray sources with luminosites ranging from 8 x 10 to the 36th to 1.2 x 10 to the 39th ergs/s have been detected. For seven of these sources, finding charts with positions accurate to less than 5 arcsec are provided. The X-ray properties and possible identifications are discussed for the eight HRI-detected sources and for two other sources, previously described by Long et al. (1981), for which upper limits are provided. It is found that most of the sources are associated with Population I markers. One source may be coincident with an optical supernova remnant. The most luminous source (by a factor of at least 25) is that associated with the optical nucleus. Because the X-ray flux from the nucleus decreased by a factor of 1/2 between the first and second observations, it is most likely that a single, compact object is responsible for the X-ray emission. It is possible that this source may be an active galactic nucleus, a massive binary X-ray source, or a low-mass X-ray binary such as are found in globular clusters within the Galaxy.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1983
- DOI:
- 10.1086/161555
- Bibcode:
- 1983ApJ...275..571M
- Keywords:
-
- Astronomical Spectroscopy;
- Galactic Nuclei;
- Heao 2;
- Position (Location);
- Spiral Galaxies;
- X Ray Sources;
- Active Galactic Nuclei;
- Binary Stars;
- High Resolution;
- Radiant Flux Density;
- Radio Spectra;
- Supernova Remnants;
- Visible Spectrum;
- Astrophysics