KEPLER OBSERVATIONS OF RAPID OPTICAL VARIABILITY IN ACTIVE GALACTIC NUCLEI

Over three quarters in 2010-2011, Kepler monitored optical emission from four active galactic nuclei (AGNs) with ~30 minute sampling, >90% duty cycle, and 0.1% repeatability. These data determined the AGN optical fluctuation power spectral density (PSD) functions over a wide range in temporal frequency. Fits to these PSDs yielded power-law slopes of –2.6 to –3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGNs exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN variability models but seem consistent with first-order magnetorotational instability theoretical calculations of accretion disk fluctuations.

[1]  A. J. Drake,et al.  Variability-selected Quasars in MACHO Project Magellanic Cloud Fields , 2002, astro-ph/0209513.

[2]  James Liebert,et al.  The Einstein Observatory Medium Sensitivity Survey - Optical identifications for a complete sample of X-ray sources , 1983 .

[3]  Paul F. Fougere,et al.  On the accuracy of spectrum analysis of red noise processes using maximum entropy and periodogram methods: Simulation studies and application to geophysical data , 1985 .

[4]  M. A. Malkan,et al.  Spectral Energy Distributions of Active Galactic Nuclei between 0.1 and 100 Microns , 1986 .

[5]  University of Leicester,et al.  On characterizing the variability properties of X-ray light curves from active galaxies , 2003 .

[6]  M. Miller,et al.  THE TIME VARIABILITY OF GEOMETRICALLY THIN BLACK HOLE ACCRETION DISKS. II. VISCOSITY-INDUCED GLOBAL OSCILLATION MODES IN SIMULATED DISKS , 2008, 0812.0365.

[7]  M. R. Haas,et al.  OVERVIEW OF THE KEPLER SCIENCE PROCESSING PIPELINE , 2010, 1001.0258.

[8]  C. Kochanek.  Quantitative Interpretation of Quasar Microlensing Light Curves , 2003, astro-ph/0307422.

[9]  C. D. Laney,et al.  BROAD-LINE REVERBERATION IN THE KEPLER-FIELD SEYFERT GALAXY Zw 229-015 , 2011, 1103.2153.

[10]  E. Bullock,et al.  MODELING THE TIME VARIABILITY OF SDSS STRIPE 82 QUASARS AS A DAMPED RANDOM WALK , 2010, 1004.0276.

[11]  Tokyo,et al.  Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79 , 2008, 0812.0810.

[12]  Andrew King,et al.  Accretion Power in Astrophysics: ACCRETION FLOWS , 2002 .

[13]  Andrew King,et al.  Accretion Power in Astrophysics: Contents , 2002 .

[14]  P. Uttley,et al.  Active galactic nuclei as scaled-up Galactic black holes , 2006, Nature.

[15]  M. Skrutskie,et al.  The Two Micron All Sky Survey (2MASS) , 2006 .

[16]  M. C. Miller,et al.  THE TIME VARIABILITY OF GEOMETRICALLY THIN BLACK HOLE ACCRETION DISKS. I. THE SEARCH FOR MODES IN SIMULATED DISKS , 2008, 0805.2950.

[17]  Hema Chandrasekaran,et al.  Pixel-level calibration in the Kepler Science Operations Center pipeline , 2010, Astronomical Telescopes + Instrumentation.

[18]  J. Krolik,et al.  GRMHD PREDICTION OF CORONAL VARIABILITY IN ACCRETING BLACK HOLES , 2009, 0907.1655.

[19]  Michael J. Kurtz,et al.  The Updated Zwicky Catalog (UZC) , 1999, astro-ph/9904265.

[20]  Usa,et al.  QUANTIFYING QUASAR VARIABILITY AS PART OF A GENERAL APPROACH TO CLASSIFYING CONTINUOUSLY VARYING SOURCES , 2009, 0909.1326.

[21]  P. Uttley,et al.  X-Ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies , 2003, astro-ph/0303273.

[22]  K. Nandra,et al.  A Cutoff in the X-Ray Fluctuation Power Density Spectrum of the Seyfert 1 Galaxy NGC 3516 , 1998, astro-ph/9810481.

[23]  I. M. McHardy,et al.  Measuring the broad-band power spectra of active galactic nuclei with RXTE , 2002 .

[24]  Bradley M. Peterson,et al.  Correlated Long-Term Optical and X-Ray Variations in NGC 5548 , 2003, astro-ph/0301216.

[25]  Howard Isaacson,et al.  Kepler Planet-Detection Mission: Introduction and First Results , 2010, Science.

[26]  Brandon C. Kelly,et al.  Are the Variations in Quasar Optical Flux Driven by Thermal Fluctuations , 2009 .

[27]  C. Fryer,et al.  MHD SIMULATIONS OF ACCRETION ONTO Sgr A*: QUIESCENT FLUCTUATIONS, OUTBURSTS, AND QUASIPERIODICITY , 2006, astro-ph/0611269.

[28]  Variability in active galactic nuclei: confrontation of models with observations , 2001, astro-ph/0110707.