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The evolution of the UV-to-mm extragalactic background light : evidence for a top-heavy initial mass function?

Cowley , William I. and Lacey, Cedric G. and Baugh, Carlton M. and Cole, Shaun and Frenk, Carlos S. and Lagos, Claudia del P. (2019) 'The evolution of the UV-to-mm extragalactic background light : evidence for a top-heavy initial mass function?', Monthly notices of the Royal Astronomical Society., 487 (3). pp. 3082-3101.


We present predictions for the UV-to-mm extragalactic background light (EBL) from a recent version of the GALFORM semi-analytical model of galaxy formation which invokes a top-heavy stellar initial mass function (IMF) for galaxies undergoing dynamically-triggered bursts of star formation. We combine GALFORM with the GRASIL radiative transfer code for computing fully self-consistent UV-to-mm spectral energy distributions for each simulated galaxy, accounting for the absorption and re-emission of stellar radiation by interstellar dust. The predicted EBL is in near-perfect agreement with recent observations over the whole UV-to-mm spectrum, as is the evolution of the cosmic spectral energy distribution over the redshift range for which observations are available (z ≲ 1). We show that approximately 90 per cent of the EBL is produced at z < 2 although this shifts to higher redshifts for sub-mm wavelengths. We assess whether the top-heavy IMF in starbursts is necessary in order to reproduce the EBL at the same time as other key observables, and find that variant models with a universal solar-neighborhood IMF display poorer agreement with EBL observations over the whole UV-to-mm spectrum and fail to match the counts of galaxies in the sub-mm.

Item Type:Article
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Publisher statement:© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
Date accepted:14 May 2019
Date deposited:14 June 2019
Date of first online publication:13 June 2019
Date first made open access:No date available

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