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A physical model for z ∼ 2 dust-obscured galaxies

Narayanan, Desika and Dey, Arjun and Hayward, Christopher C. and Cox, Thomas J. and Bussmann, R. Shane and Brodwin, Mark and Jonsson, Patrik and Hopkins, Philip F. and Groves, Brent and Younger, Joshua D. and Hernquist, Lars (2010) A physical model for z ∼ 2 dust-obscured galaxies. Monthly Notices of the Royal Astronomical Society, 407 (3). pp. 1701-1720. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20200521-163330707

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Abstract

We present a physical model for the origin of z∼ 2 dust-obscured galaxies (DOGs), a class of high-redshift ultraluminous infrared galaxies (ULIRGs) selected at 24 μm which are particularly optically faint (F_(24 μm)/F)R > 1000). By combining N-body/smoothed particle hydrodynamic simulations of high-redshift galaxy evolution with 3D polychromatic dust radiative transfer models, we find that luminous DOGs (with F₂₄ ≳ 0.3 mJy at z ∼ 2) are well modelled as extreme gas-rich mergers in massive (∼5 × 10¹²–10¹³ M_⊙) haloes, with elevated star formation rates (SFR; ∼500–1000 M_⊙ yr⁻¹) and/or significant active galactic nuclei (AGN) growth (Ṁ_(BH) ≳ 0.5 M_,⊙ yr⁻¹)whereas less luminous DOGs are more diverse in nature. At final coalescence, merger-driven DOGs transition from being starburst dominated to AGN dominated, evolving from a ‘bump’ to a power-law (PL) shaped mid-IR (Infrared Array Camera, IRAC) spectral energy distribution (SED). After the DOG phase, the galaxy settles back to exhibiting a ‘bump’ SED with bluer colours and lower SFRs. While canonically PL galaxies are associated with being AGN dominated, we find that the PL mid-IR SED can owe both to direct AGN contribution and to a heavily dust obscured stellar bump at times that the galaxy is starburst dominated. Thus, PL galaxies can be either starburst or AGN dominated. Less luminous DOGs can be well-represented either by mergers or by massive (M_(baryon) ≈ 5 × 10¹¹ M_⊙) secularly evolving gas-rich disc galaxies (with SFR ≳ 50 M_⊙ yr⁻¹)). By utilizing similar models as those employed in the submillimetre galaxy (SMG) formation study of Narayanan et al., we investigate the connection between DOGs and SMGs. We find that the most heavily star-forming merger-driven DOGs can be selected as submillimetre galaxies, while both merger-driven and secularly evolving DOGs typically satisfy the BzK selection criteria. The model SEDs from the simulated galaxies match observed data reasonably well, though Mrk 231 and Arp 220 templates provide worse matches. Our models provide testable predictions of the physical masses, dust temperatures, CO linewidths and location on the M_(BH)–M_(bulge) relation of DOGs. Finally, we provide public SED templates derived from these simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/j.1365-2966.2010.16997.xDOIArticle
http://arxiv.org/abs/0910.2234arXivDiscussion Paper
ORCID:
AuthorORCID
Narayanan, Desika0000-0002-7064-4309
Dey, Arjun0000-0002-4928-4003
Hayward, Christopher C.0000-0003-4073-3236
Brodwin, Mark0000-0002-4208-798X
Hopkins, Philip F.0000-0003-3729-1684
Groves, Brent0000-0002-9768-0246
Hernquist, Lars0000-0001-6950-1629
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 May 10. Received 2010 May 10; in original form 2009 October 12. This paper is dedicated to the original DOG himself, Cordozar Calvin Broadus, Jr. We are grateful to Ranga-Ram Chary, Vandana Desai, Brandon Kelly, Kai Noeske, Jason Melbourne and Alex Pope for helpful conversations. DN thanks the NOAO in Tucson for hospitality, where part of this study was conducted. The authors are grateful to the W. M. Keck Foundation for hosting the Napa Galaxy Evolution workshop where the ideas for much of this project came about. AD is supported by NOAO, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. CCH was funded by an NSF Graduate Research Fellowship. TC and MB acknowledge support from the W. M. Keck Foundation. RSB acknowledges financial assistance from HST grant GO10890, which is provided by NASA through a grant from the Space Telescope Science Institute which is operated by AURA under NASA contract NAS5-26555. PJ was supported by programs HST-AR-10678 and 10958, provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555, and by Spitzer Theory Grant 30183 from the Jet Propulsion Laboratory. Support for PFH was provided by the Miller Institute for Basic Research in Science, University of California, Berkeley. The simulations in this paper were run on the Odyssey cluster supported by the Harvard FAS Research Computing Group.
Funders:
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
National Optical Astronomy Observatory (NOAO)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
NASAGO10890
NASANAS5-26555
NASAHST-AR-10678
NASAHST-AR-10958
JPL30183
Miller Institute for Basic Research in ScienceUNSPECIFIED
Harvard UniversityUNSPECIFIED
NASA Hubble FellowshipUNSPECIFIED
Subject Keywords:dust, extinction, galaxies: formation, galaxies: high-redshift, galaxies: ISM, galaxies: starburst, cosmology: theory 1 INTR
Issue or Number:3
Record Number:CaltechAUTHORS:20200521-163330707
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200521-163330707
Official Citation:Desika Narayanan, Arjun Dey, Christopher C. Hayward, Thomas J. Cox, R. Shane Bussmann, Mark Brodwin, Patrik Jonsson, Philip F. Hopkins, Brent Groves, Joshua D. Younger, Lars Hernquist, A physical model for z∼ 2 dust-obscured galaxies, Monthly Notices of the Royal Astronomical Society, Volume 407, Issue 3, September 2010, Pages 1701–1720, https://doi.org/10.1111/j.1365-2966.2010.16997.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103400
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:22 May 2020 17:10
Last Modified:22 May 2020 17:10

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