ROSAT HRI Observations of the Starburst Galaxy M82
Abstract
Gas-dynamical models of starburst galaxies predict that supernova heating creates a bubble of hot gas which breaks out of the disk. Some models predict a polar outflow in which the hot gas escapes along an edge-brightened chimney-like structure, while others predict spherical galactic winds. In order to test these models we have obtained a 25 ksec ROSAT HRI image of the starburst galaxy M82. Our HRI image has a resolution of about 5''(70 pc) and a field of view of about 30' (20 kpc). The image includes photons with energies between 0.2 and 1.5 keV and is almost an order of magnitude more sensitive than previous images. The X-ray emission extends perpendicular to the disk 3-4 kpc which is comparable to the extent of the emission detected with the Einstein IPC, although our resolution is more than a factor of 10 better. The emission is neither collimated nor spherically distributed, but has a conical distribution in which the emission close to the center of the galaxy is more compact than the emission farther away from the disk. The X-ray emission is not edge-brightened and decreases in hardness with distance from the center of the galaxy. The mean energy in the core is about 0.85 keV, while the mean energy a few kpc from the disk is about 0.25 keV. The shape, temperature, and lack of edge-brightening of the emission is in conflict with some starburst models. ES wishes to acknowledge support from a NASA Graduate Student Research Program Fellowship.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1992
- Bibcode:
- 1992AAS...181.4910S