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An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman break Galaxies

Koprowski, MP; Coppin, KEK; E. Geach, J; Dudzevičiūtė, U; Smail, Ian; Almaini, O; An, Fangxia; Blain, AW; Chapman, SC; Chen, Chian-Chou; Conselice, CJ; Dunlop, JS; Farrah, D; Gullberg, B; Hartley, W; Ivison, RJ; Karska, A; Maltby, D; MaÅek, K; Michałowski, MJ; Pope, A; Salim, S; Scott, D; Simpson, CJ; Simpson, JM; Swinbank, AM; Thomson, AP; Wardlow, JL; van der Werf, PP; Whitaker, KE

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman break Galaxies Thumbnail


Authors

MP Koprowski

KEK Coppin

J E. Geach

O Almaini

Fangxia An

AW Blain

SC Chapman

Chian-Chou Chen

CJ Conselice

JS Dunlop

D Farrah

B Gullberg

W Hartley

RJ Ivison

A Karska

D Maltby

K MaÅek

MJ Michałowski

A Pope

S Salim

D Scott

CJ Simpson

JM Simpson

AP Thomson

JL Wardlow

PP van der Werf

KE Whitaker



Abstract

We analyse 870μm 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 parametrised 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 (⁠fobs≡SFRIR/SFRUV+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.

Journal Article Type Article
Acceptance Date Jan 2, 2020
Online Publication Date Jan 20, 2020
Publication Date Mar 31, 2020
Deposit Date Jan 23, 2020
Publicly Available Date Jan 23, 2020
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 492
Issue 4
Pages 4927-4944
DOI https://doi.org/10.1093/mnras/staa160
Public URL https://durham-repository.worktribe.com/output/1273089

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Copyright Statement
This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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