(Hibiki) Resonance: Art, Healing, and the Holistic View of Life.

M.F.A. Thesis. University of Hawaiʻi at Mānoa 2018

Suzaku observations of the hard X-ray variability of MCG-6-30-15: the effects of strong gravity around a Kerr black hole

Suzaku has, for the first time, enabled the hard X-ray variability of the Seyfert 1 galaxy MCG-6-30-15 to be measured. The variability in the 14-45 keV band, which is dominated by a strong reflection hump, is quenched relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-law continuum. The broadband spectral variability can be decomposed into two components - a highly variable power-law and constant reflection - as previously inferred from other observations in the 2-10 keV band. The strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii. Our results are consistent with the predictions of the light bending model which invokes the very strong gravitational effects expected very close to a rapidly spinning black hole.Comment: accepted for publication in PASJ Suzaku special issu

The long Suzaku observation of MCG-6-30-15

We report results from a long observation of MCG-6-30-15 with Suzaku. Thanks to its unprecedented sensitivity in the hard band, we could, for the first time, investigate the hard X-ray variability of the source. The variability in the HXD/PIN 14-45 keV band (dominated by a strong reflection hump) is suppressed relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-law continuum. The broadband spectral variability can be decomposed into two components - a highly variable power-law and constant reflection - as previously inferred from other observations in the 2-10 keV band. The strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii, confirming that MCG-6-30-15 most likely harbours a rapidly spinning Kerr black hole.</p