Takehiro Miyakawa, Ken Ebisawa, Hajime Inoue
We propose a new spectral model for the Seyfert 1 Galaxy MCG-6-30-15 that can
describe most of the 1 - 40 keV spectral variation effectively by a single
parameter. Our spectral model includes three continuum components; (1) a direct
power-law component, (2) a heavily absorbed power-law component by thick
photoionized material, and (3) a cold disk reflection component far from the
black hole with moderate solid-angle including a narrow fluorescent iron line.
The ionized iron K-edge of the heavily absorbed power-law component can explain
most of the seemingly broad "disk line" spectral feature, so that our model
does not require an additional broad iron emission line. In the course of
spectral variations, the "total normalization", which is sum of the
normalizations of the direct power-law component and the absorbed component, is
not significantly variable, while the "covering fraction", which is defined as
ratio of the normalization of the absorbed component to the total
normalization, is much more significantly variable. We propose that MCG-6-30-15
has a moderately extended, not significantly variable central X-ray source,
partially covered by intervening optically thick clouds having internal
ionization structure, so that observed flux and spectral variations are
primarily caused by variation of the partial covering fraction. These absorbing
clouds probably correspond to the fast-moving broad line region (BLR) clouds.
View original:
http://arxiv.org/abs/1202.2797
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