The extended X-ray halo of the Crab-like SNR G21.5-0.9
R. S. Warwick
R. G. Griffiths
N. Schurch
R. Willingale
J. -. P. Bernard
F. Bocchino
D. Lumb
A. Decourchelle
P. Ferrando
F. Haberl
A. M. Read
D. Schaudel
La Palombara N
S. Mereghetti
A. Tiengo
2381/26447
https://figshare.le.ac.uk/articles/journal_contribution/The_extended_X-ray_halo_of_the_Crab-like_SNR_G21_5-0_9/10118885
Recent XMM-Newton observations reveal an extended ( $r \approx 150''$) low-surface brightness X-ray halo in the supernova remnant G21.5-0.9. The near circular symmetry, the lack of any limb brightening and the non-thermal spectral form, all favour an interpretation of this outer halo as an extension of the central synchrotron nebula rather than as a shell formed by the supernova blast wave and ejecta. The X-ray spectrum of the nebula exhibits a marked spectral softening with radius, with the power-law spectral index varying from $\Gamma = 1.63 \pm 0.04$ in the core to $\Gamma = 2.45 \pm 0.06$ at the edge of the halo. Similar spectral trends are seen in other Crab-like remnants and reflect the impact of the synchrotron radiation losses on very high energy electrons as they diffuse out from the inner nebula. A preliminary timing analysis provides no evidence for any pulsed X-ray emission from the core of G21.5-0.9.
2012-10-24 09:21:45
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