The Suzaku View of the Disk-Jet Connection in the Low-excitation Radio Galaxy NGC 6251
Hardcastle, M. J.; Croston, J. H.; Gandhi, P.; Lee, J. C.; Kraft, R. P.; Evans, D. A.; Summers, A. C.
United States, United Kingdom, Japan
Abstract
We present results from an 87 ks Suzaku observation of the canonical low-excitation radio galaxy (LERG) NGC 6251. We have previously suggested that LERGs violate conventional active galactic nucleus unification schemes: they may lack an obscuring torus and are likely to accrete in a radiatively inefficient manner, with almost all of the energy released by the accretion process being channeled into powerful jets. We model the 0.5-20 keV Suzaku spectrum with a single power law of photon index Γ = 1.82+0.04 - 0.05, together with two collisionally ionized plasma models whose parameters are consistent with the known galaxy- and group-scale thermal emission. Our observations confirm that there are no signatures of obscured, accretion-related X-ray emission in NGC 6251, and we show that the luminosity of any such component must be substantially sub-Eddington in nature.