The Remarkable X-Ray Spectrum of the Broad-Line Radio Galaxy 3C 445

Abstract

We present the results of the analysis of an archival 15 ks XMM-Newton observation of the nearby (z=0.057) radio-loud source 3C 445, optically classified as a broad-line radio galaxy. While the RGS data are of insufficient quality to allow a meaningful analysis, the EPIC data show a remarkable X-ray spectrum. The 2-10 keV continuum is described by a heavily absorbed (N_H~10²²-10²³ cm^-2) power law with photon index Γ~1.4 and strong (R~2) cold reflection. A narrow, unresolved Fe Kα emission line is detected, confirming previous findings, with EW~120 eV. A soft excess is present below 2 keV over the extrapolation of the hard X-ray power law, which we model with a power law with the same photon index as the hard power law, absorbed by a column density N_H=6×10²⁰ cm^-2 in excess to Galactic. A host of emission lines are present below 2 keV, confirming previous indications from ASCA, due to H- and He-like O, Mg, and Si. We attribute the origin of the lines to a photoionized gas, with properties very similar to radio-quiet obscured AGNs. Two different ionized media, or a single stratified medium, are required to fit the soft X-ray data satisfactorily. The similarity of the X-ray spectrum of 3C 445 to Seyferts underscores that the central engines of radio-loud and radio-quiet AGNs similarly host both cold and warm gas.