Long-term spectral changes in the partial-covering candidate narrow-line Seyfert 1 galaxy 1H 0707-495

Abstract

We compare two XMM-Newton observations of the narrow-line Seyfert 1 galaxy 1H 0707-495, separated by two years, and discuss the results in terms of the partial-covering phenomenon. The second longer observation once again displays a sharp (<200 eV) spectral drop above 7 keV; however, in comparison with the first observation, the edge depth and energy have changed significantly. In addition to changes in the edge parameters, the high-energy spectrum appears steeper. The changes in the high-energy continuum can be adequately explained in terms of a partial-covering absorber outflowing from the central region. The low-energy spectrum also shows significant long-term spectral variability, including a substantial increase in the disc temperature, detection of a ~0.9-keV emission feature and the presence of warm absorption that was also detected during the ASCA mission, but not seen during the first XMM-Newton observation. The large increase in disc temperature, and more modest rise in luminosity, can be understood if we consider the slim-disc model for 1H 0707-495. In addition, the higher disc luminosity could be the driving force behind the outflow scenario and the reappearance of a warm medium during the second XMM-Newton observation.