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Title: Investigating the variability of active galactic nuclei using combined multi-quarter Kepler data

We used photometry from the Kepler satellite to characterize the variability of four radio-loud active galactic nuclei (AGNs) on timescales from years to minutes. The Kepler satellite produced nearly continuous high precision data sets which provided better temporal coverage than possible with ground based observations. We have now accumulated 11 quarters of data, eight of which were reported in our previous paper. In addition to constructing power spectral densities (PSDs) and characterizing the variability of the last three quarters, we have linked together the individual quarters using a multiplicative scaling process, providing data sets spanning ∼2.8 yr with >98% coverage at a 30 minute sampling rate. We compute PSDs on these connected data sets that yield power law slopes at low frequencies in the approximate range of –1.5 to –2.0, with white noise seen at higher frequencies. These PSDs are similar to those of both the individual quarters and to those of ground-based optical observations of other AGNs. We also have explored a PSD binning method intended to reduce a bias toward shallow slope fits by evenly distributing the points within the PSDs. This tends to steepen the computed PSD slopes, especially when the low frequencies are relatively poorly fit.more » We detected flares lasting several days in which the brightness increased by ∼15%-20% in one object, as well a smaller flare in another. Two AGNs showed only small, ∼1%-2%, fluctuations in brightness.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Department of Physics, The College of New Jersey, P.O. Box 7718, Ewing, NJ 08628 (United States)
  2. Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States)
  3. Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 321-100, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22357172
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 785; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ACCURACY; APPROXIMATIONS; BRIGHTNESS; FLUCTUATIONS; GALAXIES; GALAXY NUCLEI; NOISE; PHOTOMETRY; QUASARS; SATELLITES; SPECTRAL DENSITY