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Diffuse radio emission detection around B2 0258+35

Submitter: Aleksandar Shulevski
Description: An AGN relic or not? The jury is still out on this one, at least until we image it in more radio frequency bands. Depicted is extended diffuse emission with an extent of 240 kpc (imaged using the WSRT at 1.4 GHz) around the radio source B2 0258+35 (CSS source, inset). The contours are overlaid on a DSS2 optical image, showing the host galaxy, NGC 1167. The contours are plotted in such a way as to show clearly the brightness difference between the CSS source (1.8 Jy) and the extended emission (119 mJy - integrated flux). Note the double-lobed appearance of the diffuse emission, and the similarity in orientation with the CSS source.

The host galaxy has a huge disk of HI which appears undisturbed, discounting the possibility of a recent merger. In addition, stellar population studies have ruled out that possibility. So, what's feeding the currently active CSS source? It could be gas accreting from the halo. If the diffuse emission is confirmed to be a relic, we have a snapshot of subsequent episodes of AGN activity seen at radically different spatial scales.

For more info, see the recently published paper in Astronomy & Astrophysics: Shulevski et al. 2012, A&A 545, A91
Copyright: Aleksandar Shulevski
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