Luigi Gallo (MPE)
The large broad-band sensitivity of XMM-Newton has allowed for the detection of 2-10 keV spectral curvature and/or sharp spectral drops in the X-ray spectra of many NLS1. Two competing models have evolved: (1) partial covering of the intrinsic spectrum by a dense, patchy absorber, or (2) modification of the reflection and power-law components by general relativistic effects. During the talk I will give a general overview of these observations, with particular emphasis on IRAS 13224-3809 and 1H 0707-495. I will focus on the spectral and timing properties and describe how the observered characteristics fit (or do not fit) each model. I will discuss the advantages and disadvantages of each model, and present possible future tests.