Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?

Abstract

We test the consistency of active galactic nuclei (AGN) optical flux variability with the $\text{damped random walk}$ (DRW) model. Our sample consists of 20 multi-quarter $\text{Kepler}$ AGN light curves including both Type 1 and 2 Seyferts, radio-loud and -quiet AGN, quasars, and blazars. $\text{Kepler}$ observations of AGN light curves offer a unique insight into the variability properties of AGN light curves because of the very rapid ($11.6-28.6$ min) and highly uniform rest-frame sampling combined with a photometric precision of $1$ part in $10^5$ over a period of 3.5 yr. We categorize the light curves of all 20 objects based on visual similarities and find that the light curves fall into 5 broad categories. We measure the first order structure function of these light curves and model the observed light curve with a general broken power-law PSD characterized by a short-timescale power-law index $\gamma$ and turnover timescale $\tau$. We find that less than half the objects are consistent with a DRW and observe variability on short timescales ($\sim 2$ h). The turnover timescale $\tau$ ranges from $\sim 10-135$ d. Interesting structure function features include pronounced dips on rest-frame timescales ranging from $10-100$ d and varying slopes on different timescales. The range of observed short-timescale PSD slopes and the presence of dip and varying slope features suggests that the DRW model may not be appropriate for all AGN. We conclude that AGN variability is a complex phenomenon that requires a more sophisticated statistical treatment.

arXiv comment20 pages, 13 figures

References in corpus (37)

• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• The SDSS Quasar Survey: Quasar Luminosity Function from Data Release Three
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources
• Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton
• Quantifying Quasar Variability As Part of a General Approach To Classifying Continuously Varying Sources
• Is Quasar Optical Variability a Damped Random Walk?
• A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
• CGRaBS: An All-Sky Survey of Gamma-Ray Blazar Candidates
• Flexible and Scalable Methods for Quantifying Stochastic Variability in the Era of Massive Time-Domain Astronomical Data Sets
• Kepler Observations of Rapid Optical Variability in Active Galactic Nuclei
• Quasar Accretion Disks Are Strongly Inhomogeneous
• Selecting Quasars by their Intrinsic Variability
• On the use of structure functions to study blazar variability: caveats and problems
• Optimal Time-Series Selection of Quasars
• Variability in black hole accretion discs
• Quasar Selection Based on Photometric Variability
• Demystifying Kepler Data: A Primer for Systematic Artifact Mitigation
• Analysis of Random Number Generators Using Monte Carlo Simulation
• Broad-Line Reverberation in the Kepler-Field Seyfert Galaxy Zw 229-015
• The Color Variability of Quasars
• Stochastic Modeling of the Fermi/LAT Gamma-ray Blazar Variability
• Reliable Identifications of AGN from the WISE, 2MASS and Rosat all-sky surveys
• A novel variability-based method for quasar selection: evidence for a rest frame ~54 day characteristic timescale
• Quasar Black Hole Mass Estimates in the Era of Time Domain Astronomy
• A new list of extra-galactic radio jets
• Kepler observations of rapid optical variability in the BL Lac object W2R1926+42
• Characterizing the Optical Variability of Bright Blazars: Variability-Based Selection of Fermi AGN
• Assessment of stochastic and deterministic models of 6304 quasar lightcurves from SDSS Stripe 82
• Discovery of 5000 Active Galactic Nuclei behind the Magellanic Clouds
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. II. The nature of four unidentified sources
• Variability-based AGN selection using image subtraction in the SDSS and LSST era
• Investigating Active Galactic Nuclei Variability Using Combined Multi-Quarter Kepler Data
• Kepler Photometry of Four Radio-Loud AGN in 2010-2012
• The structure and X-ray radiation spectra of illuminated accretion disks in AGN. III. Modeling fractional variability

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