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

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posted on 2023-06-09, 13:36 authored by Naveen A Reddy, Pascal A Oesch, Rychard Bouwens, Mireia Montes, Garth D Illingworth, Charles C Steidel, Pieter G van Dokkum, Hakim Atek, Marcella C Carollo, Anna Cibinel, Brad Holden, Ivo Labbé, Dan Magee, Laura Morselli, Erica J Nelson, Stephen WilkinsStephen Wilkins
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 (ß) and dust attenuation (L IR/L UV = IRX). Our sample significantly extends the range of L UV and ß probed in previous UV-selected samples, including those as faint as M 1600 = -17.4 ($\simeq 0.05{L}_{\mathrm{UV}}^{* }$) and -2.6 lesssim ß lesssim 0.0. IRX is measured using stacks of deep Herschel data, and the results are compared with predictions of the IRX-ß relation for different assumptions of the stellar population model and obscuration curve. We find that z = 1.5–2.5 galaxies have an IRX-ß 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 ß by a factor of gsim3. IRX is roughly constant with L UV for L UV gsim 3 × 109 L ?. Thus, the commonly observed trend of fainter galaxies having bluer ß may simply reflect bluer intrinsic slopes for such galaxies, rather than lower obscurations. The IRX-ß relation for young/low-mass galaxies at z gsim 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, ? 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.

Funding

University of Sussex Astronomy Consolidated Grant 2017-2020; G2050; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/P000525/1

History

Publication status

  • Published

File Version

  • Published version

Journal

The Astrophysical Journal

ISSN

1538-4357

Publisher

American Astronomical Society

Issue

56

Volume

853

Page range

1-20

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Astronomy Centre Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-05-30

First Open Access (FOA) Date

2018-05-30

First Compliant Deposit (FCD) Date

2018-05-30

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