Spectral energy distribution variations of nearby Seyfert galaxies during AGN watch monitoring programs
AffiliationUniv Arizona, Steward Observ
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PublisherOXFORD UNIV PRESS
CitationSpectral energy distribution variations of nearby Seyfert galaxies during AGN watch monitoring programs 2018, 474 (2):1590 Monthly Notices of the Royal Astronomical Society
Rights© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
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AbstractWe present and analyse quasi-simultaneous multi-epoch spectral energy distributions (SEDs) of seven reverberation-mapped active galactic nuclei (AGNs) for which accurate black hole mass measurements and suitable archival data are available from the 'AGNWatch' monitoring programs. We explore the potential of optical-UV and X-ray data, obtained within 2 d, to provide more accurate SED-based measurements of individual AGN and quantify the impact of source variability on key measurements typically used to characterize the black hole accretion process plus on bolometric correction factors at 5100 angstrom, 1350 angstrom and for the 2-10 keV X-ray band, respectively. The largest SED changes occur on long time-scales (greater than or similar to 1 year). For our small sample, the 1 mu m to 10 keV integrated accretion luminosity typically changes by 10 per cent on short time-scales (over 20 d), by similar to 30 per cent over a year, but can change by 100 per cent or more for individual AGN. The extreme ultraviolet (EUV) gap is the most uncertain part of the intrinsic SED, introducing a similar to 25 per cent uncertainty in the accretion-induced luminosity, relative to the model independent interpolation method that we adopt. That aside, our analysis shows that the uncertainty in the accretion-induced luminosity, the Eddington luminosity ratio and the bolometric correction factors can be reduced (by a factor of two or more) by use of the SEDs built from data obtained within 20 d. However, (M) over dot and eta are mostly limited by the unknown EUV emission and the unknown details of the central engine and our aspect angle.
VersionFinal published version
SponsorsFREJA Fellowship - Faculty of Natural Sciences at the University of Copenhagen; Marie Curie International Incoming Fellowship [REA FP7-PEOPLE-2009-IIF, 255190]; Danish Council for Independent Research [DFF 4002-00275]; Dark Cosmology Centre; Danish National Research Foundation; NASA [NAS5-26555]; NASA Office of Space Science [NNX09AF08G]