Abstract
Focusing on hard X-ray variability, we reanalyzed Suzaku data of the Type I Seyfert galaxy MCG-6-30-15 obtained in 2006. Intensity-sorted spectroscopy and a principal-component analysis consistently revealed a very hard component that varies independently of the dominant power-law emission. Although the exact nature of this hard component has not yet been identified, it can be modeled as a power-law with a photon index of ∼2 affected by a partial covering absorption, or as a thermal Comptonization emission with a relatively large optical depth. When this component is included in the fitting model, the time-averaged 2.5-55 keV spectrum of MCG-6-30-15 can be reproduced successfully by invoking a mildly broadened iron line with its emission region located at ≥8 times the gravitational radii from the central black hole, and a moderate reflection with a covering fraction of ∼3.4π. This result implies that the solution of a highly spinning black hole in MCG-6-30-15, obtained byMiniutti et al. (2007, PASJ, 59, S315) using the same Suzaku data as ours, is a model-dependent result.
Original language | English |
---|---|
Pages (from-to) | 449-458 |
Number of pages | 10 |
Journal | Publications of the Astronomical Society of Japan |
Volume | 63 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2011 Apr 25 |
Externally published | Yes |
Keywords
- Active-galaxies
- Galaxies
- Individual (MCG-6-30-15)-galaxies
- Seyfert-X-rays
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science