X-Ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies

A. Markowitz, R. Edelson, S. Vaughan, P. Uttley, I. M. George, R. E. Griffiths, S. Kaspi, A. Lawrence, I. McHardy, K. Nandra, K. Pounds, J. Reeves, N. Schurch, R. Warwick

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By combining complementary monitoring observations spanning long, medium, and short timescales, we have constructed power spectraldensities (PSDs) of six Seyfert 1 galaxies. These PSDs span >~4orders of magnitude in temporal frequency, sampling variations ontimescales ranging from tens of minutes to over a year. In at least fourcases, the PSD shows a ``break,'' a significant departure from a powerlaw, typically on timescales of the order of a few days. This is similarto the behavior of Galactic X-ray binaries (XRBs), lower mass compactsystems with breaks on timescales of seconds. NGC 3783 shows tentativeevidence for a doubly broken power law, a feature that until now hasbeen seen only in the (much better defined) PSDs of low-state XRBs. Itis also interesting that (when one previously observed object is addedto make a small sample of seven) an apparently significant correlationis seen between the break timescale T and the putative black hole massMBH, while none is seen between break timescale andluminosity. The data are consistent with the linear relationT=MBH/106.5Msolar extrapolation over6-7 orders of magnitude is in reasonable agreement with XRBs. All ofthis strengthens the case for a physical similarity between Seyfert 1galaxies and XRBs.
Original languageEnglish
Pages (from-to)96-114
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 1 Aug 2003


  • Galaxies: Active
  • Galaxies: Seyfert
  • X-Rays: Galaxies


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