An X-ray survey of the 2Jy sample. II: X-ray emission from extended structures

Mingo, Beatriz; Hardcastle, M. J.; Ineson, J.; Mahatma, V.; Croston, J. H.; Dicken, D.; Evans, D. A.; Morganti, R. and Tadhunter, C. (2017). An X-ray survey of the 2Jy sample. II: X-ray emission from extended structures. Monthly Notices of the Royal Astronomical Society, 470(3) pp. 2762–2779.



The 2Jy sample is a survey of radio galaxies with flux densities above 2 Jy at 2.7 GHz. As part of our ongoing work on the southern subset of 2Jy sources, in paper I of this series we analysed the X-ray cores of the complete 2Jy sample with redshifts 0.05 < z < 0.7. For this work we focus on the X-ray emission associated with the extended structures (jets, lobes, and environments) of the complete subset of 2Jy sources with 0.05 < z < 0.2, that we have observed with Chandra. We find that hotspots and jet knots are ubiquitous in FRII sources, which also inhabit systematically poorer environments than the FRI sources in our sample. Spectral fits of the hotspots with good X-ray statistics invariably show properties consistent with synchrotron emission, and we show that inverse-Compton mechanisms under-predict the X-ray emission we observe by 1–2 orders of magnitude. Inverse-Compton emission is detected from many of the lobes in our sample, and we find that the lobes of the FRII sources show magnetic fields lower by up to an order of magnitude than expected from equipartition extrapolations. This is consistent with previous results, which show that most FRII sources have electron energy densities higher than minimum energy requirements.

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