your ID: 0139 
First Name: Piotr 
Last Name: Zycki 
Affiliation: Copernicus Astronomical Center 
Title: X-ray variability of the Seyfert 2 galaxy NGC 4945 
Authors: P. Zycki, M. Mueller, G. Madejski, C. Done, A. Niedzwiecki 
Topic: 1 
Session: oral 
Abstract: 
We developed an improved method of simulating the power density spectra of 
unevenly sampled lightcurves. The method was then applied to the X-ray 
emission from the Seyfert 2 galaxy NGC 4945. The source is highly variable 
on timescale of days despite it being absorbed by a Thomson-thick, 
presumably extended, absorber. The mass of the central black hole is known 
(approx. 10^6 Solar masses) thanks to observations of megamasers. The 
inferred PDS is rather harder (relatively more power on short time scales) 
than the canonical PDS shape observed in Seyfert 1 galaxies. This is 
contrary to the expected influence of X-ray scattering on PDS, which 
should reduce the amplitude of high-frequency variability. We discuss 
whether the intrinsic variability might have been boosted by effects 
related to high inclination of the X-ray source.