Chandra and XMM-Newton observations of NGC 6251

被引:60
作者
Evans, DA
Hardcastle, MJ
Croston, JH
Worrall, DM
Birkinshaw, M
机构
[1] Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England
[2] Univ Hertfordshire, Sch Phys Astron & Math, Hatfield AL10 9AB, Herts, England
[3] CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France
关键词
galaxies : active; galaxies : individual : NGC 6251; galaxies : jets; X-rays : galaxies;
D O I
10.1111/j.1365-2966.2005.08900.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present new X-ray observations of the nucleus, jet and extended emission of the nearby radio galaxy NGC 6251 using the Chandra/ACIS-S camera, together with a reanalysis of archival Chandra/ACIS-I and XMM - Newton/EPIC data. We find that the nuclear X-ray spectrum is well fitted with an absorbed power law, and that there is tentative, but not highly significant, evidence for Fe K alpha emission. We argue that the observed nuclear X-ray emission is likely to originate in a relativistic jet, based on the double-peaked nature, and our synchrotron self-Compton modelling, of the radio to X-ray spectral energy distribution. However, we cannot rule out a contribution from an accretion flow. We resolve X-ray jet emission in three distinct regions, and argue in favour of a synchrotron origin for all three; inverse Compton emission models are possible but require extreme parameters. We detect thermal emission on both galaxy and group scales, and demonstrate that hot gas can confine the jet, particularly if relativistic beaming is important. We show evidence that the radio lobe has evacuated a cavity in the X-ray-emitting gas, and suggest that the lobe is close to the plane of the sky, with the jet entering the lobe close to the surface nearest to the observer.
引用
收藏
页码:363 / 382
页数:20
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