The X-ray halo of G21.5 - 0.9
Abstract
The emission of the plerion G21.5 - 0.9 appears more extended in X-rays than in radio. This is an unexpected result because it would imply that short-lived X-ray electrons may reach distances even larger than radio electrons. Applying an empirical relationship between dust scattering optical depth and photoelectric column density, the measured column density leads to a large optical depth at 1 keV, of about 1. Therefore we investigate the hypothesis that the detected halo be an effect of dust scattering, re-analyzing an Cal/PV XMM-Newton observation of G21.5 - 0.9 and critically examining it in terms of a dust scattering model. We also present a spectral analysis of a prominent extended feature in the northern sector of the halo.
- Publication:
-
Advances in Space Research
- Pub Date:
- 2004
- DOI:
- 10.1016/j.asr.2003.04.025
- arXiv:
- arXiv:astro-ph/0305398
- Bibcode:
- 2004AdSpR..33..398B
- Keywords:
-
- Astrophysics
- E-Print:
- 6 pages, 5 figures, Latex, txfonts cospar and natbib macro packages, to appear in "High Energy Studies of Supernova Remnants and Neutron Stars" (COSPAR 2002), Eds. W. Hermsen, W. Becker, Advances in Space Research, in press