Partial Covering Interpretation of the X-Ray Spectrum of the NLS1 1H 0707−495

Abstract

The X-ray spectrum of 1H 0707$-$495 obtained with XMM-Newton showing a deep flux drop at $\sim 7 \,\mathrm{keV}$ (Boller et al. 2002) is studied based on the partial covering concept. The previously inferred extreme iron overabundance can be reduced down to ${}\sim 3\times$ solar if the hard component gradually steepens at high energies. The spectral shape supports that 1H 0707$-$495 is an AGN analogue of the galactic black-hole binaries in the soft state. Interpreting the soft excess as the emission from an optically-thick disk, the minimum black hole mass $M$ is estimated to be $2 \cdot 10^6 \,{{{M}_{\odot}}}$ from the intrinsic luminosity corrected for partial covering. Based on the slim disk model, the observed disk temperature implies that the luminosity is close to the Eddington limit. The rapid and large flux variations with little change in the spectral shape can also be explained, if not all, as due to changes in the partial covering fraction. Partial covering may account for the large variability characteristics of NLS1.