8th HEAD Meeting, 8-11 September, 2004
Session 26 AGN/Galactic Nuclei
Poster, Friday, September 10, 2004, 9:00am-10:00pm

## [26.02] The Power Spectrum of the Active Galaxy Markarian 478

A. R. Villarreal (University of Arizona), T. E. Strohmayer (NASA/GSFC)

We report results of a timing analysis of observations of the bright Seyfert 1 galaxy Mrk 478, obtained with the European Photon Imaging Camera (EPIC) on board \textit{XMM-Newton}. The source was observed on December 23, 2001 for 31 ksec. Light curves for Mrk 478 were produced from images obtained with the EPIC (PN and MOS) instruments. The average count rate in the PN was 8.4 cts/sec and the source varied significantly during the observation. The X-ray hardness ratios, determined from the EPIC PN camera measurements, exhibit weak spectral evolution. The power spectrum of X-ray variability for Mrk 478 was calculated via the standard Fast Fourier Transform (FFT) technique. We find that the power spectral density (PSD) of Mrk 478 over the 0.15--15 keV energy range is well modeled by a power-law with a slope of \alpha \approx 2.0. The fractional variability (rms) in the frequency range 3.4 \times 10-4-–0.90 Hz was \approx 29%. These values are similar in form to other active galaxies such as Mrk 766. Further, we find no evidence of Quasi-Periodic Oscillations (QPOs) in our high frequency power spectrum.

Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.