1ES 1927+654: Persistent and rapid X-ray variability in an AGN with low intrinsic neutral X-ray absorption and narrow optical emission lines

Abstract

We present X-ray and optical observations of the X-ray bright AGN 1ES 1927+654. The X-ray observations obtained with ROSAT and Chandra reveal persistent, rapid and large scale variations, as well as steep 0.1-2.4 keV (Gamma = 2.6 +/- 0.3) and 0.3-7.0 keV (Gamma = 2.7 +/- 0.2) spectra. The measured intrinsic neutral X-ray column density is approximately 7e20cm^-2. The X-ray timing properties indicate that the strong variations originate from a region, a few hundred light seconds from the central black hole, typical for type 1 AGN. High quality optical spectroscopy reveals a typical Seyfert 2 spectrum with some host galaxy contamination and no evidence of Fe II multiplets or broad hydrogen Balmer wings. The intrinsic optical extinction derived from the BLR and NLR are A_V >= 3.7 and A_V=1.7, respectively. The X-ray observations give an A_V value of less than 0.58, in contrast to the optical extinction values. We discuss several ideas to explain this apparent difference in classification including partial covering, an underluminous BLR or a high dust to gas ratio.

8 pages including 10 figures. Accepted for publication in Astronomy and Astrophysics

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• The XMM-SSC survey of hard-spectrum XMM-Newton sources 1: optically bright sources
• A radio, optical, UV and X-ray view of the enigmatic changing look Active Galactic Nucleus 1ES~1927+654 from its pre- to post-flare states
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