X-ray reflection in the Seyfert galaxy 1H0419-577 revealing strong relativistic effects in the vicinity of a Kerr black hole

Abstract

We report results obtained from six XMM-Newton observations of the Seyfert galaxy 1H 0419-577. Here we show that the X-ray spectrum and variability are well described by a two-component model comprising a power law with constant spectral shape and variable normalisation and a much more constant ionised reflection component from the inner accretion. One of the observations was performed when the source was in a particularly low flux state in which the X-ray spectrum is rather peculiar and exhibits a very flat hard spectrum with broad residuals below 6.6 keV and a steep soft excess below about 1 keV. We interpret the spectrum as being reflection-dominated by X-ray reprocessed emission from the inner accretion disc. The primary continuum is almost completely unobserved possibly because of strong light bending towards the central black hole. The ionised reflection model simultaneously accounts for the broad residuals and hard flat spectrum and for the soft excess. The same model provides an excellent description of the data at all the other flux levels, the most important difference being a variation in the power law normalisation. Our results imply that most of the X-ray emission in this source originates from within few gravitational radii from the central black hole and requires that the compact object is an almost maximally spinning Kerr black hole. (abridged)