2008AJ....136.2343G

We report on the first detection of hard X-ray photons (E > 2.5 keV) in the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007 which was the active galactic nucleus (AGN) with the softest X-ray spectrum during the ROSAT All-Sky Survey. The AGN is clearly detected at a level of about 2 x 10^–17 W/m2 in the observed 0.3-10.0 keV band by Swift in a 50 ks observation in 2007 September. For the first time since the ROSAT All-Sky Survey observation in 1990 it was possible to derive an X-ray photon distribution by adding together all Swift observations that have been performed so far (85.5 ks in total). This photon distribution is consistent with an X-ray spectrum of an AGN with a partial covering absorber with a column density in the order of ∼1x10²³/cm2 and a covering fraction of about 90%. A comparison with the 2002 Chandra data suggests that WPVS 007 has become brighter by a factor of about 4. The Swift data also suggest that the absorber which is causing the current low state may have started to disappear. This disappearance is indicated by a significant change in the hardness ratio from a very soft X-ray state during the 2005 October to 2007 January observations to a rather hard X-ray state in the 2007 September observations. In the UV, WPVS 007 seems to become fainter by up to 0.5 mag over the last two years. The optical to X-ray spectral slope derived from the spectral energy distribution is α_ox= 2.5 which classifies WPVS 007 as an X-ray weak AGN. After correcting for reddening and X-ray absorption, α_ox becomes 1.9 and the luminosity in the Big-Blue-Bump is log L_BBB= 37.7 [W], which translates into an Eddington ratio L/L_Edd~ 1.