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 I ES 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 (Γ = 2.6 ′ 0.3) and 0.3-7.0 keV (F = 2.7 ′ 0.2) spectra. The measured intrinsic neutral X-ray column density is approximately 7 x 10 2 0 cm - 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.