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The X-ray variability of AGN and the anomalous behavior of NGC 6814The power spectra of the X-ray variable AGN are typically scale invariant with no characteristic timescale. The one strong exception to this is NGC 6814, where the EXOSAT data showed evidence for a periodic component at 12200 +/- 100 seconds. The power spectra of a GINGA lightcurve from this source, found using simulation techniques to account for the uneven sampling, also cannot be well fit by a single power law. A folded light curve analysis of GINGA data shows strong evidence for this periodic component. A second GINGA observation of this source taken one year later is consistent with the phenomena being completely periodic and phase coherent for 7 periods in the range of 12,110-12,145 seconds. Including the (optimistic) limits from the folding selects a period of 12130.39 +/- 0.05 seconds. Phase coherence is not maintained between this and the EXOSAT observations, as the structure of the folded light curves is very different. Thus the periodicity is long lived and stable, but phase coherence is only maintained on timescales of about 1 year.
Document ID
19930045814
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Done, C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Madejski, G. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mushotzky, R. F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Turner, T. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Koyama, K.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kunieda, H.
(Nagoya Univ. Japan)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Testing the AGN paradigm; Proceedings of the 2nd Annual Topical Astrophysics Conference, Univ. of Maryland, College Park, Oct. 14-16, 1991 (A93-29801 11-90)
Publisher: American Institute of Physics
Subject Category
Astrophysics
Accession Number
93A29811
Distribution Limits
Public
Copyright
Other

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