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

T. Taro Shimizu; Richard F. Mushotzky; Marcio Meléndez; Michael J. Koss; Amy J. Barger; Lennox L. Cowie

doi:10.1093/mnras/stw3268

paper

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

arXiv:1612.03941 · doi:10.1093/mnras/stw3268

Abstract

We combine the Herschel Space Observatory PACS and SPIRE photometry with archival WISE photometry to construct the spectral energy distributions (SED) for over 300 local ( $z < 0.05$ ), ultra-hard 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 cut-off powerlaw 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 (SFR) 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 $μ$ m AGN luminosities, as well as determine the best mid-to-far IR colors for identifying AGN dominated galaxies in the IR regime. We find that for nearly 30 per cent of our sample, the 70 $μ$ m emission contains a significant contribution from the AGN ( $> 0.5$ ), especially at higher luminosities ( $L_{14 - 195 keV} > 1 0^{42.5}$ ergs 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.

26 pages, 17 figures, 3 Tables, accepted for publication in MNRAS

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

Abstract

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