ar X iv : a st ro - p h / 03 05 39 8 v 1 2 1 M ay 2 00 3 THE X - RAY HALO OF G 21 . 5 – 0 . 9
نویسندگان
چکیده
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.
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