科研之友
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摘要
Multi-epoch X-ray spectroscopy (0.3-25 keV) of the Seyfert 1.2 galaxy Mrk 79 (UGC3973) spanning nearly 8 yr and a factor of 3 in broad-band flux are analysed. The data are obtained at seven epochs with either XMM-Newton or Suzaku. Comparison with contemporaneous RXTE monitoring indicates that all flux states of Mrk 79 are represented by the data. The spectra are fitted in a self-consistent manner adopting a power law and ionized reflection to describe the broad-band continuum. Modification of the spectra by a distant photoionized medium, seen predominantly in emission, is also included. Under the assumption that the inner disc is at the innermost stable circular orbit, our blurred reflection models give a spin of a = 0.7 +/- 0.1. The reflection component in each spectrum is weaker than that predicted by simple reflection models. If the illuminating X-ray emission is produced by flares above the disc that move at mildly relativistic velocities, however, diminished reflection is expected. Light bending due to strong gravity near black holes can influence how the illuminating and reflected fluxes are observed; variations in Mrk 79 do not suggest that light bending is important in this source.
- 出版日期2011-2
