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Published November 1, 2018 | Published + Accepted Version
Journal Article Open

The AGN luminosity fraction in merging galaxies

Abstract

Galaxy mergers are key events in galaxy evolution, often causing massive starbursts and fueling active galactic nuclei (AGNs). In these highly dynamic systems, it is not yet precisely known how much starbursts and AGNs, respectively, contribute to the total luminosity, at what interaction stages they occur, and how long they persist. Here we estimate the fraction of the bolometric infrared (IR) luminosity that can be attributed to AGNs by measuring and modeling the full ultraviolet to far-IR spectral energy distributions (SEDs) in up to 33 broad bands for 24 merging galaxies with the Code for Investigating Galaxy Emission. In addition to a sample of 12 confirmed AGNs in late-stage mergers, found in the Infrared Astronomical Satellite Revised Faint Source Catalog, our sample includes a comparison sample of 12 galaxy mergers from the Spitzer Interacting Galaxies Survey, mostly early stage. We also perform SED modeling of merger simulations to validate our methods, and we supplement the SEDs with mid-IR spectra of diagnostic lines obtained with Spitzer's InfraRed Spectrograph. The estimated AGN contributions to the IR luminosities vary from system to system from 0 per cent up to ∼91 per cent but are significantly greater in the later-stage, more luminous mergers, consistent with what is known about galaxy evolution and AGN triggering.

Additional Information

© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2018 July 20. Received 2018 June 29; in original form 2018 January 12. We thank the National Science Foundation, the Smithsonian Astrophysical Observatory, and Jonathan McDowell for providing JD the ability to complete this research through the NSF Research Experience for Undergraduates Program held at the SAO. We would also like to thank Aliza Beverage for her assistance and feedback with the research and writing process, and D. Burgarella and the CIGALE team for their advice. The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no.1262851, and by the Smithsonian Institution. The Flatiron Institute is supported by the Simons Foundation. HAS, ASW, and JRM-G acknowledge partial support from NASA grants NNX14AJ61G and NNX15AE56G. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. This research has made use of the NASA/IPAC Extragalactic Database (NED), operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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Published - sty2056.pdf

Accepted Version - 1801.04328

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Created:
August 19, 2023
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October 19, 2023