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Herschel-ATLAS/GAMA : how does the far-IR luminosity function depend on galaxy group properties?

Guo, Qi and Lacey, Cedric G. and Norberg, Peder and Cole, Shaun and Baugh, Carlton and Frenk, Carlos and Cooray, Asantha and Dye, Simon and Bourne, N. and Dunne, L. and Eales, S. and Ivison, R.J. and Maddox, S.J. and Alpasan, M. and Baldry, I. and Driver, S.P. and Robotham, A. (2014) 'Herschel-ATLAS/GAMA : how does the far-IR luminosity function depend on galaxy group properties?', Monthly notices of the Royal Astronomical Society., 442 (3). pp. 2253-2270.

Abstract

We use the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) Phase I data to study the conditional luminosity function of far-IR (250 μm) selected galaxies in optically selected galaxy groups from the Galaxy And Mass Assembly (GAMA) spectroscopic survey, as well as environmental effects on the far-IR-to-optical colour. We applied two methods, which gave consistent results for the far-IR conditional luminosity functions. The direct matching method matches H-ATLAS sources to GAMA/SDSS (Sloan Digital Sky Survey) galaxies, then links the optical counterparts to GAMA groups. The stacking method counts the number of far-IR sources within the projected radii of GAMA groups, subtracting the local background. We investigated the dependence of the far-IR (250 μm) luminosity function on group mass in the range 1012 < Mh < 1014 h−1 M⊙ and on redshift in the range 0 < z < 0.4, using a sample of 3000 groups containing H-ATLAS sources with GAMA redshifts over an area of 126 deg2. We find that the characteristic 250 μm luminosity, L*(250), increases with group mass up to Mh ∼ 1013 h−1 M⊙, but is roughly constant above this, while it increases with redshift at high group masses, but less so at low masses. We also find that the group far-IR luminosity-to-mass ratio L(250)/Mh increases with redshift and is higher in low-mass groups. We estimate that around 70 per cent of the 250 μm luminosity density in the local Universe is contributed by groups with Mh > 1012 h−1 M⊙. We also find that the far-IR-to-optical colours of H-ATLAS galaxies are independent of group mass over the range 1012 < Mh < 1014 h−1 M⊙ in the local Universe. We also compare our observational results with recent semi-analytical models, and find that none of these galaxy formation models can reproduce the conditional far-IR luminosity functions of galaxy groups.

Item Type:Article
Keywords:Galaxies: clusters: general, Galaxies: formation, Galaxies: haloes, Galaxies: luminosity function mass function, Cosmology: theory, Infrared: galaxies.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1093/mnras/stu962
Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:27 June 2014
Date of first online publication:August 2014
Date first made open access:No date available

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