The nature of submillimetre and highly star-forming galaxies in the EAGLE simulation

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McAlpine , S , Smail , I , Bower , R G , Swinbank , A M , Trayford , J W , Theuns , T , Baes , M , Camps , P , Crain , R A & Schaye , J 2019 , ' The nature of submillimetre and highly star-forming galaxies in the EAGLE simulation ' , Monthly Notices of the Royal Astronomical Society , vol. 488 , no. 2 , pp. 2440-2454 .

Title: The nature of submillimetre and highly star-forming galaxies in the EAGLE simulation
Author: McAlpine, Stuart; Smail, Ian; Bower, Richard G.; Swinbank, A. M.; Trayford, James W.; Theuns, Tom; Baes, Maarten; Camps, Peter; Crain, Robert A.; Schaye, Joop
Contributor organization: Particle Physics and Astrophysics
Department of Physics
Date: 2019-09
Language: eng
Number of pages: 15
Belongs to series: Monthly Notices of the Royal Astronomical Society
ISSN: 0035-8711
Abstract: We exploit EAGLE, a cosmological hydrodynamical simulation, to reproduce the selection of the observed submillimetre (submm) galaxy population by selecting the model galaxies at z >= 1 with mock submm fluxes S-850 mu m >= 1mJy. We find a reasonable agreement between the model galaxies within this sample and the properties of the observed submm population, such as their star formation rates (SFRs) at z <3, redshift distribution, and many integrated galaxy properties. We find that the median redshift of the S-850 (mu m) >= 1mJy model population is z approximate to 2.5, and that they are massive galaxies (M-* similar to 10(11)M(circle dot)) with high dust masses (M-dust similar to 10(8)M(circle dot)), gas fractions (f(gas) approximate to 50 per cent), and SFRs ((*) approximate to 100 M-circle dot yr(-1)). In addition, we find that they have major and minor merger fractions similar to the general population, suggesting that mergers are not the sole driver of the high SFRs in the model submm galaxies. Instead, the S-850 (mu m) >= 1mJy model galaxies yield high SFRs primarily because they maintain a significant gas reservoir as a result of hosting an undermassive black hole relative to comparably massive galaxies. Not all 'highly star-forming' ((*) >= 80M(circle dot) yr(-1)) EAGLE galaxies have submm fluxes S-850 (mu m) >= 1 mJy. We investigate the nature of these highly star-forming 'Submm-Faint' galaxies (i.e. (*) = 80 M-circle dot yr(-1) but S-850 (mu m) <1mJy) and find that they are similar to the model submm galaxies, being gas rich and hosting undermassive black holes. However, they are also typically at higher redshifts (z > 4) and are lower mass (M-* similar to 10(10) M-circle dot). These typically higher redshift galaxies show stronger evidence for having been triggered by major mergers, and critically, they are likely missed by most current submm surveys due to their higher dust temperatures and lower dust masses.
Subject: galaxies: active
galaxies: evolution
galaxies: formation
galaxies: high-redshift
galaxies: starburst
115 Astronomy, Space science
Peer reviewed: Yes
Rights: cc_by_nc_sa
Usage restriction: openAccess
Self-archived version: publishedVersion

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