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A direct calibration of thtae IRX-beta relation in Lyman-break Galaxies at z=3-5

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posted on 25.09.2018, 11:23 by M. P. Koprowski, K. E. K. Coppin, J. E. Geach, R. J. McLure, O. Almaini, A. W. Blain, M. Bremer, N. Bourne, S. C. Chapman, C. J. Conselice, J. S. Dunlop, D. Farrah, W. Hartley, A. Karim, K. K. Knudsen, M. J. Michalowski, D. Scott, C. Simpson, D. J. B. Smith, P. P. van der Werf
We use a sample of 4209 Lyman-break galaxies (LBGs) at z 3, 4, and 5 in the UKIRT Infrared Deep Sky Survey Ultra Deep Survey field to investigate the relationship between the observed slope of the stellar continuum emission in the ultraviolet, β, and the thermal dust emission, as quantified via the so-called ‘infrared excess’ (IRX ≡ LIR/LUV). Through a stacking analysis, we directly measure the 850-μm flux density of LBGs in our deep (0.9 mJy) James Clerk Maxwell Telescope SCUBA-2 850-μm map as well as deep public Herschel/SPIRE 250-, 350-, and 500-μm imaging. We establish functional forms for the IRX–β relation to z ∼ 5, confirming that there is no significant redshift evolution of the relation, and that the resulting average IRX–β curve is consistent with a Calzetti-like attenuation law. Comparing our results with recent works in the literature, we confirm that discrepancies in the slope of the IRX–β relation are driven by biases in the methodology used to determine the ultraviolet slopes. Consistent results are found when IRX–β is evaluated by stacking in bins of stellar mass, and we argue that the near-linear IRX–M relationship is a better proxy for correcting observed ultraviolet luminosities to total star formation rates, provided an accurate handle on M and also gives clues as to the physical driver of the role of dust-obscured star formation in high-redshift galaxies

Funding

KEKC and MPK acknowledge support from the UK’s Science and Technology Facilities Council (grant agreement No. ST/M001008/1). JEG is supported by the Royal Society. MJM acknowledges the support of the National Science Centre, Poland through the POLONEZ grant agreement No. 2015/19/P/ST9/04010; this project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665778. KK acknowledges support from the Swedish Research Council and the Knut and Alice Wallenberg Foundation. NB acknowledges support from the European Research Council Advanced Investigator Program, COSMICISM (ERC-2012-ADG-20120216, PI R.J.Ivison).

History

Citation

Monthly Notices of the Royal Astronomical Society, 2018, 479 (4), pp. 4355-4366 (12)

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP), Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Acceptance date

06/06/2018

Copyright date

2018

Available date

25/09/2018

Publisher version

https://academic.oup.com/mnras/article/479/4/4355/5036533

Language

en