The XMM-Newton view of NGC 6251

Abstract

We report on the nuclear X-ray properties of the radio galaxy NGC 6251 observed with XMM-Newton. NGC 6251 is a well-known radio galaxy with intermediate FRI/II radio properties. It is optically classified as a Seyfert 2 and hosts a supermassive black hole with mass~6e8 solar masses. The 0.4-10 keV EPIC pn continuum is best fitted by two thermal components (kT~0.5 and 1.4 keV, respectively), plus a power law with photon index ~1.9 absorbed by a column density NH~5e20 cm-2. We confirm the previous ASCA detection of a strong iron line. The line, resolved in the EPIC pn spectrum, is adequately fitted with a broad (sigma~0.6 keV) Gaussian at rest-frame energy 6.4 keV with EW 220 eV. We also detect, for the first time, short-term, low-amplitude variability of the nuclear flux on a timescale of a few ks. The spectral properties argue in favor of the presence of a standard accretion disk, ruling out the base of the jet as the sole origin of the X-rays. The moderate X-ray luminosity and lack of strong intrinsic absorption suggest that NGC 6251 is a ``pure'' type 2 AGN which lacks a broad-line region.

arXiv comment7 pages, 4 figures, accepted for publication in A&A

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• Chandra and XMM-Newton Observations of NGC 6251
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• The Accretion Geometry in Radio-Loud Active Galaxies
• The XMM-Newton view of the X-ray halo and jet of NGC 6251
• A Chandra view of Naked Active Galactic Nuclei
• Dissecting the Power Sources of Low-Luminosity Emission-Line Galaxy Nuclei via Comparison of HST-STIS and Ground-Based Spectra
• Investigating the EGRET-radio galaxies link with INTEGRAL: the case of 3EG J1621+8203 and NGC 6251
• The Suzaku View of the Disk-Jet Connection in the Low Excitation Radio Galaxy NGC 6251
• The non-ballistic superluminal motion in the plane of the sky-II
• Long-Term X-Ray monitoring of NGC6251: Evidence for a jet-dominated radio galaxy