X-Ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies

By A. Markowitz, R. Edelson, S. Vaughan, P. Uttley, I. George, R. Griffiths, S. Kaspi, Andy Lawrence, I. McHardy, K. Nandra and 4 more. 2003

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By combining complementary monitoring observations spanning long, medium, and short timescales, we have constructed power spectral densities (PSDs) of six Seyfert 1 galaxies. These PSDs span ≳4 orders of magnitude in temporal frequency, sampling variations on timescales ranging from tens of minutes to over a year. In at least four cases, the PSD shows a "break," a significant departure from a power law, typically on timescales of the order of a few days. This is similar to the behavior of Galactic X-ray binaries (XRBs), lower mass compact systems with breaks on timescales of seconds. NGC 3783 shows tentative evidence for a doubly broken power law, a feature that until now has been seen only in the (much better defined) PSDs of low-state XRBs. It is also interesting that (when one previously observed object is added to make a small sample of seven) an apparently significant correlation is seen between the break timescale T and the putative black hole mass MBH, while none is seen between break timescale and luminosity. The data are consistent with the linear relation T = MBH/106.5 M☉; extrapolation over 6-7 orders of magnitude is in reasonable agreement with XRBs. All of this strengthens the case for a physical similarity between Seyfert 1 galaxies and XRBs.

Subfields: Astronomy and Astrophysics, Instrumentation

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Investigating a fluctuating-accretion model for the spectral-timing properties of accreting black hole systems (2005, background): “…monitoring campaigns typically show power law PSDs with a slope ∼ −1 at low frequencies, bending or breaking at high frequencies to slopes ∼ −2 or steeper (e.g. Uttley, McHardy & Papadakis c© 2005 RAS, MNRAS 000, 1–14 2002; Markowitz et al. 2003; McHardy et al. 2004, 2005; Uttley & McHardy 2005).”
X-ray variability of 104 active galactic nuclei - XMM-Newton power-spectrum density profiles (2012, methodology): “…papers have demonstrated a strong, approximately linear correlation between the PSD bend timescale (Tb = 1/νb) and the black hole mass (e.g. Uttley et al., 2002; Markowitz et al., 2003; Vaughan et al., 2005), as expected from simple scalingrguments (Shakura & Sunyaev, 1976; Fender et al., 2006).”
A simple test for periodic signals in red noise (2004, background): “It is also now known that at low frequencies the power spectra of Seyferts break from a single power law (e.g. Uttley et al. 2002; Markowitz et al. 2003).”
Measuring the Masses of Supermassive Black Holes (2014, background): “– X-ray observations also reveal that the power spectral density function of accret- ing black holes shows a characteristic “break frequency,” becoming much steeper at high frequency (Markowitz et al. 2003; Papadakis 2004; McHardy et al. 2006).”
Combined long and short timescale X-ray variability of NGC 4051 with RXTE and XMM-Newton (2003, methodology): “Edelson and Nandra (1999), Pounds et al. (2001) and Markowitz et al. (2003) have all now demonstrated PSD flattening in other AGN at low frequencies, using RXTE data.”
First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN (2014, background): “…Arévalo et al. 2008; Breedt et al. 2009; Chatterjee et al. 2011), X-ray timing analysis to constrain variability mechanisms in Seyferts (e.g., Markowitz et al. 2003; McHardy et al. 2006), and coordinated multi-wavelength campaigns on blazars during giant outbursts to constrain spectral…”
Reverberation Mapping of High-Luminosity Quasars: First Results (2006, background): “This has been observed in X-rays (e.g., Lawrence & Papadakis 1993; Uttley et al. 2002; Markowitz et al. 2003; O’Neill et al. 2005), and possibly in the UV-optical bands (e.g., Giveon et al. 1999; Cid Fernandes et al. 2000; Vanden Berk et al. 2004).”
A light bending model for the X-ray temporal and spectral properties of accreting black holes (2003, background): “We point out here that broad iron lines are seen in AGN such as NGC 4051 and MCG–6-30-15 whose power spectral density (PSD) shows remarkable common features with that of the BHC Cyg X-1 in its high rather than low state (Vaughan, Fabian & Nandra 2003; Markowitz et al. 2003; McHardy et al. 2003).”
On characterizing the variability properties of X-ray light curves from active galaxies (2003, methodology): “Recent timing studies have indeed found evidence that the steep power-law PSDs of Seyfert 1s show a flattening, or turnover, at low frequencies (Edelson & Nandra 1999; Uttley et al. 2002; Markowitz et al. 2003).”
Refining the fundamental plane of accreting black holes (2006, background): “Similar unification efforts are also under way analysing and comparing the variability properties of AGN and XRBs (Uttley et al. 2002; Markowitz et al. 2003; Körding & Falcke 2004; Abramowicz et al. 2004).”
X-ray reverberation around accreting black holes (2014, background): “…these efforts have also stimulated the development of techniques to study irregularly-sampled AGN data in the Fourier domain (Uttley et al. 2002; Markowitz et al. 2003), or more recently, through a combination of Fourier and time-domain approaches (Miller et al. 2010a; Kelly et al. 2011; Zoghbi…”
Accretion states and radio loudness in active galactic nuclei: analogies with X-ray binaries (2006, background): “Also the variability properties of AGN and XRBs show many similarities (Uttley, McHardy & Papadakis 2002; Markowitz et al. 2003; Abramowicz et al. 2004; Körding & Falcke 2004).”
The nature and origin of Seyfert warm absorbers (2004, unknown): “…et al. (2001a) Ark 564 NLSy1 0.02468 44.4o • • • Matsumoto et al. (2004) a Monier et al. (2001); b Beichman et al. (1986); c Santos-Lleo et al. (1995); d Markowitz et al. (2003); e Kriss et al. (2000); f Petrucci et al. (2004); g Bachev & Strigachev (2003); h Pounds et al. (2003c); i Swain et…”
Non‐linear X‐ray variability in X‐ray binaries and active galaxies (2005, background): “The remarkable similarities between various aspects of AGN and black hole XRB (BHXRB) variability suggest that the same physical mechanism underlies the variability in both cases (Uttley, McHardy & Papadakis 2002; Markowitz et al. 2003; Vaughan, Fabian & Nandra 2003; McHardy et al. 2004).”
KEPLER OBSERVATIONS OF RAPID OPTICAL VARIABILITY IN ACTIVE GALACTIC NUCLEI (2011, background): “These are always much flatter, typically having high frequency slopes of −1 to −2 (Edelson & Nandra 1999, Uttley et al. 2002, Markowitz et al. 2003).”
A Bayesian test for periodic signals in red noise (2009, background): “…values for the hyperparameters based on knowledge gained from previous studies of nearby, luminous Seyfert galaxies (e.g. Uttley et al. 2002; Markowitz et al. 2003; Papadakis 2004; McHardy et al. 2006),as outlined below, the posterior summaries (parameter means and intervals, pairwise…”
Correlated Multi-Wave Band Variability in the Blazar 3C 279 from 1996 to 2007 (2008, background): “More recent studies indicate that some Seyfert galaxies have X-ray PSDs that are fit better by a broken power law, with a steeper slope above the break frequency (Uttley et al. 2002;McHardy et al. 2004;Markowitz et al. 2003; Edelson &Nandra 1999; Pounds et al. 2001).”
MCG–6-30-15: long time-scale X-ray variability, black hole mass and active galactic nuclei high states (2005, methodology): “It is now reasonably well established that the X-ray powerspectral densities (PSDs) of AGN are broadly similar to those of galactic black hole X-ray binary systems (GBHs) (McHardy 1988; Edelson & Nandra 1999; Uttley et al. 2002; Markowitz et al. 2003; McHardy et al. 2004).”