Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

0488884 - ASÚ 2018 RIV FR eng J - Journal Article
Epitropakis, A. - Papadakis, I.E. - Dovčiak, Michal - Pecháček, Tomáš - Emmanoulopoulos, D. - Karas, Vladimír - Hardy, I.M.M.
Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry.
Astronomy & Astrophysics. Roč. 594, October (2016), A71/1-A71/17. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA MŠMT(CZ) 7E13003
Keywords : active galaxies * X-rays * accretion disks
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.014, year: 2016

We estimate time-lags as accurately as possible and fit them with theoretical models in the context of the lamp-post geometry. We also constrain the geometry of the X-ray emitting region in AGN. Given the available data, time-lags between the two energy bands can only be reliably measured at frequencies between similar to 5 x 10(-5) Hz and similar to 10(-3) Hz. The power-law and reverberation time-lag models can both fit the data well in terms of formal statistical characteristics. When fitting the observed time-lags to the lamp-post reverberation scenario, we can only constrain the height of the X-ray source. The data require, or are consistent with, a small (less than or similar to 10 gravitational radii) X-ray source height. In principle, the 5-7 keV band, which contains most of the Fe K alpha line emission, could be an ideal band for studying reverberation effects, as it is expected to be dominated by the X-ray reflection component. We here carried out the best possible analysis with XMM-Newton data. Time-lags can be reliably estimated over a relatively narrow frequency range, and their errors are rather large. Nevertheless, our results are consistent with the hypothesis of X-ray reflection from the inner accretion disc.


Permanent Link: http://hdl.handle.net/11104/0283403