Spectral Variation of the Seyfert 1 Galaxy MCG-6-30-15 observed with Suzaku

Abstract

We have investigated spectral variation of the Seyfert 1 galaxy MCG-6-30-15 observed with Suzaku in January 2006 for three separate periods spreading over fourteen days. We found that the time-averaged continuum energy spectrum between 1 keV and 40 keV can be approximated with a spectral model composed of the direct power-law component, its reflection component, two warm absorbers with different ionization states, and neutral absorption. We have taken two approaches to study its spectral variation at various timescales: The first approach is to make intensity-sliced spectra and study correlation between the intensity and spectral shape. The second approach is to study spectral changes between the intervals when the source flux is above ("bright state") and below ("faint state") the average for fixed time-intervals. In both approaches, we found a clear correlation between the intensity in the 6 -- 10 keV band and the spectral ratio of 0.5 -- 3.0 keV/6.0-- 10 keV. Such a spectral variation requires change of the apparent slope of the direct component, whereas the shape and intensity of the reflection component being invariable. The observed apparent spectral change is explained by variation of the ionization degree of one of the two warm absorbers due to intrinsic source luminosity variation. Current results suggest that the warm absorber has a critical role to explain the observed continuum spectral shape and variation of MCG-6-30-15, which is essential to constrain parameters of the putatively broadened iron line emission feature.

11 pages, accepted for publication in PASJ

References in corpus (2)

• An absorption origin for the X-ray spectral variability of MCG-6-30-15
• The broad band spectrum and variability of NGC 4151 observed by BeppoSAX

Cited by in corpus (11)

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• Observational constraints on the spin of the most massive black holes from radio observations
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• A Variable Partial Covering Model for the Seyfert 1 Galaxy MCG-6-30-15
• Modelling the Broad-band Spectra of MCG-6-30-15 with a Relativistic Reflection Model
• Suzaku Discovery of a Hard Component Varying Independently of the Power-Law Emission in MCG-6-30-15
• Suzaku observation of IRAS 00521-7054, a peculiar type-II AGN with a very broad feature at 6 keV
• Non-monotonic Keplerian velocity profiles around near-extreme braneworld Kerr black holes
• On the light-bending model of X-ray variability of MCG-6-30-15
• Origin of the X-ray Broad Iron Spectral Feature in GRS 1915+105