Optical and X-ray variability of the Seyfert galaxies NGC 5548, NGC 7469, NGC 3227, NGC 4051, NGC 4151, Mrk 509, Mrk 79, Akn 564 and quasar 1E 0754

Chesnok, NG, Sergeev, SG, 1Vavilova, IB
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2009, 25(2):150-160
Language: Ukrainian
Abstract: 

We present our results of cross-correlation analysis of the optical and X-ray light curves for eight Seyfert galaxies: NGC 5548, NGC 7469, NGC 3227, NGC 4051, NGC 4151, Mrk 509, Mrk 79, Akn 564 and for the optical spectrum of the quasar IE 0754. We obtained a high maximum value of the cross-correlation coefficient between variations in the optical and X-ray spectral regions for the Seyfert galaxies NGC 5548 and NGC 7469 (0.73 and 0.79, respectively). The time of lag calculated at the maximum of the cross-correlation function is 2.800+3.12-1.58 days for NGC 5548 and 0.6+0.9-4.3 days for NGC 7469. The result is an evidence in favour of the assumption on the Compton scattering of the X-ray flux variation in the optical region for these galaxies. The wing (except for the main maximum corresponding to the delay in optical region in relation to X-ray region) exists in the part of the cross-correlation functions which corresponds to the delay in the X-ray region in relation to optical one for the whole sample (except for Akn 564 and NGC 4151) with the time of lag of about 10 days. We present one of the methods for determination of the mass of a central black hole in AGN through the spectral line width. Using this method the mass of the central black hole in the quasar IE 0754 is estimated to be MBH = 1.01 ⋅ 108MSun. The position of IE 0754 is in a good agreement with the position of other NLSl galaxies in mass-to-luminosity diagram.

Keywords: quasar, Seyfert galaxy, X-ray variability