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The HDUV Survey: A Revised Assessment of the Relationship between UV Slope and Dust Attenuation for High-redshift Galaxies

Reddy, Naveen A. and Oesch, Pascal A. and Bouwens, Rychard J. and Montes, Mireia and Illingworth, Garth D. and Steidel, Charles C. and van Dokkum, Pieter G. and Atek, Hakim and Carollo, Marcella C. and Cibinel, Anna and Holden, Brad and Labbé, Ivo and Magee, Dan and Morselli, Laura and Nelson, Erica J. and Wilkins, Steve (2018) The HDUV Survey: A Revised Assessment of the Relationship between UV Slope and Dust Attenuation for High-redshift Galaxies. Astrophysical Journal, 853 (1). Art. No. 56. ISSN 1538-4357. doi:10.3847/1538-4357/aaa3e7.

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We use a newly assembled sample of 3545 star-forming galaxies with secure spectroscopic, grism, and photometric redshifts at z = 1.5–2.5 to constrain the relationship between UV slope (β) and dust attenuation (L_(IR)/L_(UV) ≡ IRX). Our sample significantly extends the range of L_(UV) and β probed in previous UV-selected samples, including those as faint as M_(1600) = −17.4 (≃0.05L_(UV)^*) and −2.6 ≾ β ≾ 0.0. IRX is measured using stacks of deep Herschel data, and the results are compared with predictions of the IRX−β relation for different assumptions of the stellar population model and obscuration curve. We find that z = 1.5–2.5 galaxies have an IRX−β relation that is consistent with the predictions for an SMC curve if we invoke subsolar-metallicity models currently favored for high-redshift galaxies, while the commonly assumed starburst curve overpredicts the IRX at a given β by a factor of ≳3. IRX is roughly constant with L_(UV) for L_(UV) ≳ 3 × 10^9 L_⊙. Thus, the commonly observed trend of fainter galaxies having bluer β may simply reflect bluer intrinsic slopes for such galaxies, rather than lower obscurations. The IRX−β relation for young/low-mass galaxies at z ≳ 2 implies a dust curve that is steeper than the SMC. The lower attenuations and higher ionizing photon output for low-metallicity stellar populations point to Lyman continuum production efficiencies, ξ_(ion), that may be elevated by a factor of ≈2 relative to the canonical value for L^* galaxies, aiding in their ability to keep the universe ionized at z ~ 2.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Reddy, Naveen A.0000-0001-9687-4973
Oesch, Pascal A.0000-0001-5851-6649
Bouwens, Rychard J.0000-0002-4989-2471
Montes, Mireia0000-0001-7847-0393
Illingworth, Garth D.0000-0002-6668-2011
Steidel, Charles C.0000-0002-4834-7260
van Dokkum, Pieter G.0000-0002-8282-9888
Atek, Hakim0000-0002-7570-0824
Carollo, Marcella C.0000-0003-1624-7609
Cibinel, Anna0000-0003-4578-514X
Holden, Brad0000-0002-6153-3076
Labbé, Ivo0000-0002-2057-5376
Nelson, Erica J.0000-0002-7524-374X
Additional Information:© 2018 American Astronomical Society. Received 2017 May 24. Accepted 2017 December 18. Published 2018 January 23. This work was supported by NASA through grant HST-GO-13871 and from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. K. Penner kindly provided data from his published work in electronic format. N.A.R. is supported by an Alfred P. Sloan Research Fellowship.
Group:Astronomy Department
Funding AgencyGrant Number
NASANAS 5-26555
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:dark ages, reionization, first stars dust, extinction galaxies: evolution galaxies: formation galaxies: high-redshift galaxies: ISM
Issue or Number:1
Record Number:CaltechAUTHORS:20180201-082359298
Persistent URL:
Official Citation:Naveen A. Reddy et al 2018 ApJ 853 56
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84618
Deposited By: Ruth Sustaita
Deposited On:01 Feb 2018 19:42
Last Modified:15 Nov 2021 20:21

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