X-ray reflection in the Seyfert galaxy 1H 0419-577 revealing strong relativistic effects in the vicinity of a Kerr black hole

We report results obtained from six XMM-Newton observations of the Seyfert galaxy 1H 0419-577. The source was observed in a wide range of different flux levels, allowing its long-term spectral variability to be studied in detail, as already reported recently by Pounds et al. Here we show that the X-ray spectrum is well described by a simple two-component model comprising a power law with constant spectral shape and variable normalization, and a much more constant ionized reflection component from the inner accretion disc, which carries the signature of strong relativistic effects. 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 spectral index close to 1 in the 2-10 keV band), with broad residuals below 6.6 keV (rest frame) and a steep soft excess below about I keV. We interpret the spectrum as being reflection-dominated by X-ray reprocessed emission from the inner accretion disc. The primary continuum, which illuminates the disc, is almost completely unobserved, possibly because of strong light bending towards the central supermassive black hole. The ionized reflection model simultaneously accounts for the broad hard 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 normalization. Our spectral decomposition and interpretation of the spectral variability implies that most of the X-ray emission in this source originates from within a few gravitational radii from the central black hole and requires that the compact object is almost maximally spinning.