The X-ray continuum time-lags and intrinsic coherence in AGN

Abstract

We present the results from a systematic analysis of the X-ray continuum (`hard') time-lags and intrinsic coherence between the $2-4\mathrm{keV}$ and various energy bands in the $0.3-10\mathrm{keV}$ range, for ten X-ray bright and highly variable active galactic nuclei (AGN). We used all available archival \textit{XMM-Newton} data, and estimated the time-lags following Epitropakis \& Papadakis (2016). By performing extensive numerical simulations, we arrived at useful guidelines for computing intrinsic coherence estimates that are minimally biased, have known errors, and are (approximately) Gaussian distributed. Owing to the way we estimated the time-lags and intrinsic coherence, we were able to do a proper model fitting to the data. Regarding the continuum time-lags, we are able to demonstrate that they have a power-law dependence on frequency, with a slope of $-1$, and that their amplitude scales with the logarithm of the light-curve mean-energy ratio. We also find that their amplitude increases with the square root of the X-ray Eddington ratio. Regarding the intrinsic coherence, we found that it is approximately constant at low frequencies. It then decreases exponentially at frequencies higher than a characteristic `break frequency.' Both the low-frequency constant intrinsic-coherence value and the break frequency have a logarithmic dependence on the light-curve mean-energy ratio. Neither the low-frequency constant intrinsic-coherence value, nor the break frequency exhibit a universal scaling with either the central black hole mass, or the the X-ray Eddington ratio. Our results could constrain various theoretical models of AGN X-ray variability.

arXiv comment36 pages, 6 tables, 42 figures (accepted for publication in MNRAS)

References in corpus (25)

• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• RXTE Observation of Cygnus X-1: II. Timing Analysis
• The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta
• Investigating a Fluctuating-accretion Model for the Spectral-timing Properties of Accreting Black Hole Systems
• On the X-ray time lags in the black hole candidates
• Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton
• Reverberation Mapping Measurements of Black Hole Masses in Six Local Seyfert Galaxies
• X-Ray Variability Coherence: How to Compute it, What it Means, and How it Constrains Models of Cyg X-1 and GX 339-4
• Frequency-dependent time lags in the X-ray emission of the Seyfert galaxy NGC 7469
• Narrow Iron K$\alpha$ Lines in Active Galactic Nuclei: Evolving Populations?
• Gravitational Lensing Size Scales for Quasars
• A Reverberation Lag for the High-Ionization Component of the Broad Line Region in the Narrow-Line Seyfert 1 Mrk 335
• Detection of a possible X-ray Quasi-periodic Oscillation in the Active Galactic Nucleus 1H~0707-495
• Spectral-timing evidence for a Very High State in the Narrow Line Seyfert 1 Ark 564
• X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags
• Timing the warm absorber in NGC 4051
• Phase Lags and Coherence of X-Ray Variability in Black Hole Candidates
• A panchromatic view of PKS 0558-504: an ideal laboratory to study the disk-jet link
• A Reverberation-Based Black Hole Mass for MCG-06-30-15
• The Spectral Energy Distribution and Emission-Line properties of the NLS1 Galaxy Arakelian 564
• Theoretical modelling of the AGN iron-line vs continuum time-lags in the lamp-post geometry
• A 10-day ASCA Observation of the Narrow-line Seyfert~1 galaxy IRAS 13224-3809
• Short Timescale AGN X-ray Variability with EXOSAT: Black hole mass and Normalised Variability Amplitude
• Statistical properties of Fourier-based time-lag estimates
• Energy Dependent time lags in the Seyfert 1 galaxy NGC 4593

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• 2016 outburst of H~1743--322: \textit{XMM-Newton} and \textit{NuSTAR} view
• The long term X-ray time-lags of NGC 4051
• On measuring the Hubble constant with X-ray reverberation mapping of active galactic nuclei
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