Evans, D. A., Summers, A. C., Hardcastle, Martin J., Kraft, R. P., Gandhi, P., Croston, J. H., and Lee, J. C. 2011. "The Suzaku View of the Disk-Jet Connection in the Low-excitation Radio Galaxy NGC 6251." Astrophysical Journal Letters 741 (1):https://doi.org/10.1088/2041-8205/741/1/L4
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 ? = 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.