X-ray continuum variability of MCG-6-30-15

By S. Vaughan, A. C. Fabian, K. N. IoA, Cambridge, NasaGsfc. 2002

149 citations recorded by the source corpus.

This paper presents a comprehensive examination of the X-ray continuum variability of the bright Seyfert 1 galaxy MCG‐6-30-15. The source clearly shows the strong, linear correlation between rms variability amplitude and flux first seen in Galactic X-ray binaries. The highfrequency power spectral density (PSD) of MCG‐6-30-15 is examined in detail using a Monte Carlo fitting procedure and is found to be well represented by a steep power law at high frequencies (with a power-law index α ≈ 2.5), breaking to a flatter slope (α ≈ 1) below f br ≈ 0.6‐2.0 × 10 −4 Hz, consistent with the previous results of Uttley, McHardy & Papadakis. The slope of the power spectrum above the break is energy dependent, with the higher energies showing a flatter PSD. At low frequencies the variations between different energy bands are highly coherent, while at high frequencies the coherence is significantly reduced. Time lags are detected between energy bands, with the soft variations leading the hard ones. The magnitude of the lag is small (200 s for the frequencies observed) and is most likely frequency dependent. These properties are remarkably similar to the temporal properties of the Galactic black hole candidate Cygnus X-1. The characteristic time-scales in these two types of source differ by ∼10 5 ; assuming that these time-scales scale linearly with black hole mass then suggests a

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Investigating a fluctuating-accretion model for the spectral-timing properties of accreting black hole systems (2005, methodology): “As an example, the PSD of the Seyfert 1 galaxy MCG–6-30-15 can also be fit with a bending power law model obtaining flatter high-frequency slopes for higher energy light curves (Vaughan et al. 2003).”
Non‐linear X‐ray variability in X‐ray binaries and active galaxies (2005, background): “The X-ray light curves of active galactic nuclei (AGN) and X-ray binary systems (XRBs) are often dominated by strong flickering type variability, which is aperiodic (noise-like), e.g. McHardy (1988); Vaughan et al. (2003); van der Klis (1995).”
Broad iron L line and X-ray reverberation in 1H0707-495 (2009, methodology): “The coherence takes a value of 1 if the two light curves are perfectly coherent (for details on the meaning of coherence and how it is calculated, see Vaughan & Nowak 1997; Nowak et al. 1999; Vaughan et al. 2003).”
Combined long and short timescale X-ray variability of NGC 4051 with RXTE and XMM-Newton (2003, methodology): “It is interesting to note that αH is now actually better determined in AGN like NGC 4051 and MCG-6-30-15 than in GBHs like Cyg X-1.”
A global look at X-ray time lags in seyfert galaxies (2016, methodology): “We calculate the 2–10 keV fractional excess variance on 40 ks segments and 512 s time bins, using the prescription in Vaughan et al. (2003).”
MCG–6-30-15: long time-scale X-ray variability, black hole mass and active galactic nuclei high states (2005, methodology): “…lightcurve of MCG–6-30-15 in the 0.1-10 keV energy band, with 20s time bins, using data from the PN CCDs. 2.2 XMM-Newton The XMM-Newton timing observations of MCG–6-30-15 have been discussed extensively by Vaughan et al. (2003) to which we refer readers for a detailed discussion.”
X-ray variability of 104 active galactic nuclei - XMM-Newton power-spectrum density profiles (2012, methodology): “The expected Poisson noise level was calculated assuming the standard formula (e.g. Uttley et al., 2002; Vaughan et al., 2003A) and this value was used in cases where the parameterC was poorly constrained in the periodogram fitting (these observations are indicated by an asterisk in tables 2 and 3).”
A long hard look at MCG–6-30-15 with XMM-Newton (2002, methodology): “The continuum variations are energy dependent and show the PSD is a function of energy and that the hard variations are delayed with respect to the soft variations.”
The lack of variability of the iron line in MCG–6‐30‐15: general relativistic effects (2003, unknown): “We note here that the two component model also accounts (Vaughan et al 2003, in preparation) for the shape and amplitude of the r.m.s. variability spectrum of MCG– 6-30-15, plotted in Fabian et al. (2002).”
X-ray reverberation around accreting black holes (2014, background): “The errors on the rms spectrum must be calculated based on the errors expected due to Poisson noise (e.g. see Vaughan et al. 2003a), since they are independent between different energy bins in the rms spectrum, whereas the errors in the rms due to intrinsic stochastic variability (i.e. the…”