NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T06:46:24 PDT
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For refcode 2015ApJ...810...52M:
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2015ApJ...810...52M Modeling the Power Spectra of Active Galactic Nuclei with Markov Chain Monte Carlo Marshall, Kevin Abstract. We present a new method for calculating the power spectral density (PSD) of a light curve using Markov Chain Monte Carlo principles. This method allows for a faster estimation of PSD parameters, along with more robust estimates of the uncertainties for each parameter. We show that this technique is valid by applying it to a simulated light curve, where it correctly estimates the PSD parameters. We then analyze the light curves of two nearby AGNs, NGC 4593 and Mkn 79. Breaks in the PSD are detected at timescales of {3.3}_-1.9_^+4.4^ and {1.8}_-1.4_^+5.5^ days, respectively. These values agree with the predicted breaks based on scaling relationships with other AGNs and galactic black hole binary systems. The break timescale for each object agrees with the viscous timescale for a geometrically thick accretion disk, supporting the idea that a propagating fluctuation model may be responsible for variations in the X-ray flux. Key words: galaxies: active, galaxies: individual: NGC 4593, Mkn 79, galaxies: Seyfert, X-rays: galaxies
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