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

Cowley, William I.; Lacey, Cedric G.; Baugh, Carlton M.; Cole, Shaun; Frenk, Carlos S.; Lagos, Claudia del P.

Abstract

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.

Citation

Cowley, W. I., Lacey, C. G., Baugh, C. M., Cole, S., Frenk, C. S., & Lagos, C. D. 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), 3082-3101. https://doi.org/10.1093/mnras/stz1398

• Journal Article Type: Article
• Acceptance Date: May 14, 2019
• Online Publication Date: Jun 13, 2019
• Publication Date: Aug 31, 2019
• Deposit Date: Jun 4, 2019
• Publicly Available Date: Jun 14, 2019
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 487
• Issue: 3
• Pages: 3082-3101
• DOI: https://doi.org/10.1093/mnras/stz1398