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[42.05] The X-ray Power Density Spectrum of 3C 120

K. Marshall, H. R. Miller (Georgia State U.), A. P. Marscher (Boston U.)

Using the Rossi X-ray Timing Explorer (RXTE), we have observed the broad-line radio galaxy (BLRG) 3C 120 quasi-continuously for a period of nine days. These high temporal frequency data, combined with previous observations spanning 2 years, have allowed us to construct the power density spectrum (PDS) for 3C 120. Spanning more than 4 decades in temporal frequency, this represents the first PDS for a radio-loud galaxy. We find the PDS shows a steep power law of slope ~1.7 at high frequencies, flattening to a slope of ~0.6 at low frequencies, with a break frequency of ~4 \times 10^-7 Hz. This shape is very similar to that observed in galactic black hole binaries such as Cygnus X-1. We explore the relationship between break frequency and both black hole mass and luminosity, finding an estimated mass of \log (M/M_\odot) ~7.8 for the central compact object in 3C 120.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.