X-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas Accretion
| dc.creator | Evans, D. A. | |
| dc.creator | Hardcastle, M. J. | |
| dc.creator | Croston, J. H. | |
| dc.date | 2007-07-16 | |
| dc.date | 2007-08-02 | |
| dc.date.accessioned | 2026-07-07T08:21:40Z | |
| dc.date.available | 2026-07-07T08:21:40Z | |
| dc.description | We present results from Chandra and XMM-Newton spectroscopic observations of the nuclei of z<0.5 radio galaxies and quasars from the 3CRR catalog, and examine in detail the dichotomy in the properties of low- and high-excitation radio galaxies. The X-ray spectra of low-excitation sources (those with weak or absent optical emission lines) are dominated by unabsorbed emission from a parsec-scale jet, with no contribution from accretion-related emission. These sources show no evidence for an obscuring torus, and are likely to accrete in a radiatively inefficient manner. High-excitation sources (those with prominent optical emission lines), on the other hand, show a significant contribution from a radiatively efficient accretion disk, which is heavily absorbed in the X-ray when they are oriented close to edge-on with respect to the observer. However, the low-excitation/high-excitation division does not correspond to the FRI/FRII division: thus the Fanaroff-Riley dichotomy remains a consequence of the interaction between the jet and the hot-gas environment through which it propagates. Finally, we suggest that accretion of the hot phase of the IGM is sufficient to power all low-excitation radio sources, while high-excitation sources require an additional contribution from cold gas that in turn forms the cold disk and torus. This model explains a number of properties of the radio-loud active galaxy population, and has important implications for AGN feedback mechanisms. | |
| dc.description | 7 pages, 2 figures; to appear in "Extragalactic Jets: Theory and Observation from Radio to Gamma Ray", eds. T. A. Rector and D. S. De Young, ASP conference series. Typo fixed and NASA financial support acknowledgment added | |
| dc.identifier | https://arxiv.org/abs/0707.2154 | |
| dc.identifier | http://arxiv.org/abs/0707.2154 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/135392 | |
| dc.subject | Astrophysics | |
| dc.title | X-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas Accretion | |
| dc.type | text |