Herschel far-infrared photometry of the Swift Burst Alert Telescope active galactic nuclei sample of the local universe - III. Global star-forming properties and the lack of a connection to nuclear activity
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Date
2017-04
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Journal Article
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yes
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Abstract
We combine the Herschel Space Observatory PACS (Photoconductor Array Camera and
Spectrometer) and SPIRE (Spectral and Photometric Imaging Receiver) photometry with
archival WISE (Wide-field Infrared Survey Explorer) photometry to construct the spectral
energy distributions (SEDs) for over 300 local (z < 0.05), ultrahard X-ray (14–195 keV)
selected active galactic nuclei (AGN) from the Swift Burst Alert Telescope (BAT) 58-month
catalogue. Using a simple analytical model that combines an exponentially cutoff power law
with a single temperature modified blackbody, we decompose the SEDs into a host galaxy
and AGN component. We calculate dust masses, dust temperatures, and star formation rates
(SFRs) for our entire sample and compare them to a stellar mass-matched sample of local
non-AGN galaxies. We find AGN host galaxies have systematically higher dust masses, dust
temperatures, and SFRs due to the higher prevalence of late-type galaxies to host an AGN,
in agreement with previous studies of the Swift/BAT AGN. We provide a scaling to convert
X-ray luminosities into 8–1000 μm AGN luminosities, as well as determine the best mid-to-far
IR colours for identifying AGN-dominated galaxies in the IR regime. We find that for nearly
30 per cent of our sample, the 70 μm emission contains a significant contribution from the AGN
(>0.5), especially at higher luminosities (L14−195 keV > 1042.5 erg s−1). Finally, we measure
the local SFR–AGN luminosity relationship, finding a slope of 0.18, large scatter (0.37 dex),
and no evidence for an upturn at high AGN luminosity. We conclude with a discussion on
the implications of our results within the context of galaxy evolution with and without AGN
feedback.
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published
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Journal / series
Volume
466 (3)
Pages / Article No.
3161 - 3183
Publisher
Oxford University Press
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Software
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Subject
Galaxies: active; Galaxies: evolution; Galaxies: Seyfert; Galaxies: star formation; Infrared: galaxies
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Notes
It was possible to publish this article open access thanks to a Swiss National Licence with the publisher.