Understand
The X-ray spectra of the narrow line Seyfert 1 galaxy, 1H 0707-495, obtained with XMM-Newton, from time periods of varying X-ray luminosity are analysed in the context of understanding the changes to the X-ray emitting corona that lead to the extreme variability seen in the X-ray emission from active galactic nuclei (AGN).
- The emissivity profile of the accretion disc, illuminated by the X-ray emitting corona, along with previous measurements of reverberation time lags are used to infer the spatial extent of the X-ray source.
- By fitting a twice-broken power law emissivity profile to the relativistically-broadened iron K fluorescence line, it is inferred that the X-ray emitting corona expands radially, over the plane of the accretion disc, by 25 to 30 per cent as the luminosity increases, contracting again as the luminosity decreases, while increases in the measured reverberation lag as the luminosity increases would require also variation in the vertical extent of the source above the disc.
- The spectrum of the X-ray continuum is found to soften as the total X-ray luminosity increases and we explore the variation in reflected flux as a function of directly-observed continuum flux.