TY - JOUR

T1 - An ALMA survey of the SCUBA-2 cosmology legacy survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman-break galaxies

AU - Koprowski, M. P.

AU - Coppin, K. E. K.

AU - Geach, J. E.

AU - Dudzevičiūtė, U.

AU - Smail, Ian

AU - Almaini, O.

AU - An, Fangxia

AU - Blain, A. W.

AU - Chapman, S. C.

AU - Chen, Chian-Chou

AU - Conselice, C. J.

AU - Dunlop, J. S.

AU - Farrah, D.

AU - Gullberg, B.

AU - Hartley, W.

AU - Ivison, R. J.

AU - Karska, A.

AU - Maltby, D.

AU - Malek, K.

AU - Michałowski, M. J.

AU - Pope, A.

AU - Salim, S.

AU - Scott, D.

AU - Simpson, C. J.

AU - Simpson, J. M.

AU - Swinbank, A. M.

AU - Thomson, A. P.

AU - Wardlow, J. L.

AU - van der Werf, P. P.

AU - Whitaker, K. E.

N1 - This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version M P Koprowski, K E K Coppin, J E Geach, U Dudzevičiūtė, Ian Smail, O Almaini, Fangxia An, A W Blain, S C Chapman, Chian-Chou Chen, C J Conselice, J S Dunlop, D Farrah, B Gullberg, W Hartley, R J Ivison, A Karska, D Maltby, K Malek, M J Michałowski, A Pope, S Salim, D Scott, C J Simpson, J M Simpson, A M Swinbank, A P Thomson, J L Wardlow, P P van der Werf, K E Whitaker, An ALMA survey of the SCUBA-2 cosmology legacy survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman-break galaxies, Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 4, March 2020, Pages 4927–4944, https://doi.org/10.1093/mnras/staa160 is available online at: https://academic.oup.com/mnras/article/492/4/4927/5709926

PY - 2020/3/1

Y1 - 2020/3/1

N2 - We analyse 870 μm Atacama Large Millimetre Array (ALMA) dust continuum detections of 41 canonically selected z ≃ 3 Lyman-break galaxies (LBGs), as well as 209 ALMA-undetected LBGs, in follow-up of SCUBA-2 mapping of the UKIDSS Ultra Deep Survey (UDS) field. We find that our ALMA-bright LBGs lie significantly off the local IRX-beta relation and have relatively bluer rest-frame UV slopes (as parametrized by β), given their high values of the `infrared excess' (IRX ≡ LIR/LUV), relative to the average `local' IRX-β relation. We attribute this finding in part to the young ages of the underlying stellar populations but we find that the main reason behind the unusually blue UV slopes are the relatively shallow slopes of the corresponding dust attenuation curves. We show that, when stellar masses, M*, are being established via SED fitting, it is absolutely crucial to allow the attenuation curves to vary (rather than fixing it on Calzetti-like law), where we find that the inappropriate curves may underestimate the resulting stellar masses by a factor of ≃2-3× on average. In addition, we find these LBGs to have relatively high specific star-formation rates (sSFRs), dominated by the dust component, as quantified via the fraction of obscured star formation (f_obs≡ {SFR_IR/SFR_UV+IR}). We conclude that the ALMA-bright LBGs are, by selection, massive galaxies undergoing a burst of a star formation (large sSFRs, driven, for example, by secular or merger processes), with a likely geometrical disconnection of the dust and stars, responsible for producing shallow dust attenuation curves.

AB - We analyse 870 μm Atacama Large Millimetre Array (ALMA) dust continuum detections of 41 canonically selected z ≃ 3 Lyman-break galaxies (LBGs), as well as 209 ALMA-undetected LBGs, in follow-up of SCUBA-2 mapping of the UKIDSS Ultra Deep Survey (UDS) field. We find that our ALMA-bright LBGs lie significantly off the local IRX-beta relation and have relatively bluer rest-frame UV slopes (as parametrized by β), given their high values of the `infrared excess' (IRX ≡ LIR/LUV), relative to the average `local' IRX-β relation. We attribute this finding in part to the young ages of the underlying stellar populations but we find that the main reason behind the unusually blue UV slopes are the relatively shallow slopes of the corresponding dust attenuation curves. We show that, when stellar masses, M*, are being established via SED fitting, it is absolutely crucial to allow the attenuation curves to vary (rather than fixing it on Calzetti-like law), where we find that the inappropriate curves may underestimate the resulting stellar masses by a factor of ≃2-3× on average. In addition, we find these LBGs to have relatively high specific star-formation rates (sSFRs), dominated by the dust component, as quantified via the fraction of obscured star formation (f_obs≡ {SFR_IR/SFR_UV+IR}). We conclude that the ALMA-bright LBGs are, by selection, massive galaxies undergoing a burst of a star formation (large sSFRs, driven, for example, by secular or merger processes), with a likely geometrical disconnection of the dust and stars, responsible for producing shallow dust attenuation curves.

KW - dust

KW - extinction

KW - galaxies: evolution

KW - galaxies: high-redshift

KW - galaxies: ISM

KW - galaxies: star formation

KW - cosmology: observations

U2 - 10.1093/mnras/staa160

DO - 10.1093/mnras/staa160

M3 - Journal article

VL - 492

SP - 4927

EP - 4944

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -