Stanley, F., Harrison, C.M., Alexander, D.M. et al. (5 more authors) (2018) Deep ALMA photometry of distant X-ray AGN: improvements in star formation rate constraints, and AGN identification. Monthly Notices of the Royal Astronomical Society, 478 (3). pp. 3721-3739. ISSN 0035-8711
Abstract
We present the star formation rates (SFRs) of a sample of 109 galaxies with X-rayselected active galactic nuclei (AGNs) with moderate to high X-ray luminosities (L2−8 keV = 1042 − 1045 erg s−1), at redshifts 1 < z < 4.7, that were selected to be faint or undetected in the Herschel bands. We combine our deep Atacama large (sub-)millimetre array (ALMA) continuum observations with deblended 8–500 μm photometry from Spitzer and Herschel, and use infrared (IR) spectral energy distribution (SED) fitting and AGN – star formation decomposition methods. The addition of the ALMA photometry results in an order of magnitude more X-ray AGN in our sample with a measured SFR (now 37 %). The remaining 63 % of the sources have SFR upper limits that are typically a factor of 2–10 times lower than the pre-ALMA constraints. With the improved constraints on the IR SEDs, we can now identify a mid-IR (MIR) AGN component in 50 % of our sample, compared to only ∼1 % previously. We further explore the F870 μm/F24 μm–redshift plane as a tool for the identification of MIR-emitting AGN, for three different samples representing AGN-dominated, star formationdominated, and composite sources. We demonstrate that the F870 μm/F24 μm–redshift plane can successfully split between AGN and star formation-dominated sources, and can be used as an AGN identification method.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | galaxies: active; galaxies: evolution; galaxies: star formation |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/R000964/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 30 Aug 2018 09:32 |
Last Modified: | 30 Aug 2018 09:32 |
Published Version: | https://doi.org/10.1093/mnras/sty1044 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/sty1044 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:135079 |