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The X-ray Halo of G21.5-0.9

R. Bandiera·F. Bocchino
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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.

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R. Bandiera, F. Bocchino. 2003-05-21. The X-ray Halo of G21.5-0.9. https://doi.org/10.1016/j.asr.2003.04.025

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