Skip to main content

Research Repository

Advanced Search

The post-Herschel view of intrinsic AGN emission: constructing templates for galaxy and AGN emission at IR wavelengths

Bernhard, E; Tadhunter, C; Mullaney, JR; Grimmett, LP; Rosario, DJ; Alexander, DM

The post-Herschel view of intrinsic AGN emission: constructing templates for galaxy and AGN emission at IR wavelengths Thumbnail


Authors

E Bernhard

C Tadhunter

JR Mullaney

LP Grimmett

DJ Rosario



Abstract

Measuring the star-forming properties of active galactic nucleus (AGN) hosts is key to our understanding of galaxy formation and evolution. However, this topic remains debated, partly due to the difficulties in separating the infrared (i.e. 1–1000 μm) emission into AGN and star-forming components. Taking advantage of archival far-infrared data from Herschel, we present a new set of AGN and galaxy infrared templates and introduce the spectral energy distribution fitting code IRAGNSEP. Both can be used to measure infrared host galaxy properties, free of AGN contamination. To build these, we used a sample of 100 local (z < 0.3), low-to-high luminosity AGNs (i.e. Lbol ∼ 1042−46 erg s−1), selected from the 105-month Swift–BAT X-ray survey, which have archival Spitzer–IRS spectra and Herschel photometry. We first built a set of seven galaxy templates using a sample of 55 star-forming galaxies selected via infrared diagnostics. Using these templates, combined with a flexible model for the AGN contribution, we extracted the intrinsic infrared emission of our AGN sample. We further demonstrate that we can reduce the diversity in the intrinsic shapes of AGN spectral energy distributions down to a set of three AGN templates, of which two represent AGN continuum, and one represents silicate emission. Our results indicate that, on average, the contribution of AGNs to the far-infrared (λ 50 μm) is not as high as suggested by some recent work. We further show that the need for two infrared AGN continuum templates could be related to nuclear obscuration, where one of our templates appears dominated by the emission of the extended polar dust.

Citation

Bernhard, E., Tadhunter, C., Mullaney, J., Grimmett, L., Rosario, D., & Alexander, D. (2021). The post-Herschel view of intrinsic AGN emission: constructing templates for galaxy and AGN emission at IR wavelengths. Monthly Notices of the Royal Astronomical Society, 503(2), 2598-2621. https://doi.org/10.1093/mnras/stab419

Journal Article Type Article
Acceptance Date Feb 9, 2021
Online Publication Date Mar 9, 2021
Publication Date 2021-05
Deposit Date Sep 22, 2021
Publicly Available Date Sep 22, 2021
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 503
Issue 2
Pages 2598-2621
DOI https://doi.org/10.1093/mnras/stab419
Public URL https://durham-repository.worktribe.com/output/1239323

Files

Published Journal Article (22.7 Mb)
PDF

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021, The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






You might also like



Downloadable Citations