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[21.10] The Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: The Relationship between X-ray Variability and Black Hole Mass

M. Mueller, G.M. Madejski (SLAC), C. Done (Durham U.), P.T. Zycki (Copernicus Center)

The nearby Seyfert 2 galaxy NGC 4945 was observed in late 2002 using RXTE for a period of sparse sampling spanning 50 days, including 7 days of intensive monitoring. The variability of the hard X-ray nuclear flux is clearly seen in the data, while the mean count rate and the spectrum are in agreement with previous detections of NGC 4945. We analyze the variability in the 8 - 30 keV band using several different methods. By considering the scaling relationship with the mass of the central black hole, the break in the power density spectrum is expected at a timescale around 3 - 5 days. Measuring this value reliably using our data will provide the calibration for the relationship between the shape of the X-ray power density spectrum and the mass of the central black hole, which for NGC 4945 is known independently from megamaser observations.

Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.