Suzaku Observation of Diffuse X-Ray Emission from the Open Cluster Westerlund 2: a Hypernova Remnant?
Abstract
We present an analysis of Suzaku observations of the young open cluster Westerlund 2, which is filled with diffuse X-ray emission. We found that the emission consists of three thermal components, or two thermal and one non-thermal components. The upper limit of the energy flux of the non-thermal component is smaller than that in the TeV band observed with H.E.S.S. This may indicate that active particle acceleration has stopped in this cluster, and that the accelerated electrons have already cooled. The gamma-ray emission observed with H.E.S.S. is likely to come from high-energy protons, which hardly cool, in contrast with electrons. The metal abundances of the diffuse X-ray gas may indicate the explosion of a massive star in the past.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- December 2009
- DOI:
- 10.1093/pasj/61.6.1229
- arXiv:
- arXiv:0907.4750
- Bibcode:
- 2009PASJ...61.1229F
- Keywords:
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- Galaxy: open clusters and associations: individual (Westerlund 2);
- ISM: cosmic rays;
- ISM: individual (RCW 49);
- ISM: supernova remnants;
- stars: winds;
- outflows;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in PASJ