X-Ray Observations of NGC 253 and M83 with GINGA
Abstract
X-ray spectra of two starburst galaxies NGC 253 and M83 in 2-20 keV have been obtained with the X-ray astronomy satellite Ginga. The observed spectra can be described by thermal bremsstrahlung models with temperatures of 6-7 keV for both galaxies, with no significant absorption. The estimated luminosities in 2-10 keV are ~ 1 x 10^40^ ergs s^-1^ and ~ 8 x 10^39^ ergs s^-1^ for NGC 253 and M83, respectively, consistent with IPC measurements in a lower energy band. No significant iron K-emission line was detected from either galaxy with 90% upper limit on the equivalent width ~ 400 eV, suggesting a significant depletion of iron if most of the continuum emission is of thermal origin. The spectral shape and the enhanced X-ray luminosity of these two galaxies, compared with M31 or the Galaxy, suggest that a major fraction of the X-ray emission may originate from hot gas. However, the lack of an iron emission line remains a puzzle.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1990
- DOI:
- 10.1086/169468
- Bibcode:
- 1990ApJ...365..180O
- Keywords:
-
- Astronomical Spectroscopy;
- Ginga Satellite;
- Spaceborne Astronomy;
- Starburst Galaxies;
- X Ray Astronomy;
- X Ray Spectroscopy;
- Bremsstrahlung;
- Brightness Temperature;
- Emission Spectra;
- Iron;
- Star Formation;
- Astrophysics;
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 253;
- GALAXIES: INDIVIDUAL MESSIER NUMBER: M83;
- GALAXIES: X-RAYS;
- RADIATION MECHANISMS;
- STARS: FORMATION