Issue |
A&A
Volume 475, Number 1, November III 2007
|
|
---|---|---|
Page(s) | 121 - 131 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20077947 | |
Published online | 28 August 2007 |
The variable X-ray spectrum of Markarian 766 *,**
II. Time-resolved spectroscopy
1
Dept. of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA e-mail: turner@milkyway.gsfc.nasa.gov
2
Astrophysics Science Division, NASA/GSFC, Greenbelt, MD 20771, USA
3
Dept. of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
4
Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK
5
Department of Physics, Catholic University of America, Washington DC 20064, USA
Received:
25
May
2007
Accepted:
10
August
2007
Context.The variable X-ray spectra of AGN systematically show steep power-law high states and hard-spectrum low states. The hard, low state has previously been found to be a component with only weak variability. The origin of this component and the relative importance of effects such as absorption and relativistic blurring are currently not clear.
Aims.In a follow-up of previous principal components analysis we aim to determine the relative importance of scattering and absorption effects on the time-varying X-ray spectrum of the narrow-line Seyfert 1 galaxy Mrk 766.
Methods.Time-resolved spectroscopy, slicing XMM and Suzaku data down to 25 ks elements is used to investigate whether absorption or scattering components dominate the spectral variations in Mrk 766.
Results.Time-resolved spectroscopy confirms that spectral variability in Mrk 766 can be explained by either of two interpretations of principal components analysis. Detailed investigation confirm rapid changes in the relative strengths of scattered and direct emission or rapid changes in absorber covering fraction provide good explanations of most of the spectral variability. However, a strong correlation between the 6.97 keV absorption line and primary continuum together with rapid opacity changes show that variations in a complex and multi-layered absorber, most likely a disk wind, are the dominant source of spectral variability in Mrk 766.
Key words: galaxies: Seyfert / X–rays: galaxies
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.