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

Abstract

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 ( L 0.05 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×109 L e . 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.

SCUBA-2 Ultra Deep Imaging EAO Survey (Studies). III. Multiwavelength Properties, Luminosity Functions, and Preliminary Source Catalog of 450 μm Selected Galaxies

“…A similar trend is also observed in high-redshift dusty star-forming galaxies (DSFGs), which have bluer β UV at a given IRX (Oteo et al 2013;Casey et al 2014b;Bourne et al 2017;Chen et al 2017). On the other hand, at high redshift, restoptical-selected galaxies at z 2 (Reddy et al 2018), z 5 Lyman Break Galaxies (Capak et al 2015), and z 7.5 Lyman Break Galaxies (Watson et al 2015) are observed to exhibit redder β UV at given IRX values, which are more consistent with the SMC attenuation curve.…”

A3COSMOS: the dust attenuation of star-forming galaxies at z = 2.5–4.0 from the COSMOS-ALMA archive

“…In the right panel of Figure 4, we compare our findings with several results in the literature. These include stacking analyses of single dish sub-mm telescope data, Spitzer MIPS, and/or Herschel SPIRE data using rest-frame UV/Optical galaxy selections (Álvarez-Márquez et al 2016;Koprowski et al 2018;Heinis et al 2014;Whitaker et al 2017;Reddy et al 2018). Additionally, we show the stacking results of ALMA data (Bouwens et al 2016;McLure et al 2018), which utilise a smaller field of view, but have a higher angular resolution than the previous observations.…”

The Detection of [O iii] λ4363 in a Lensed, Dwarf Galaxy at z = 2.59: Testing Metallicity Indicators and Scaling Relations at High Redshift and Low Mass*

“…Because some of the emission lines have high equivalent widths, we have corrected the photometry by subtracting the contribution from the emission 2003). As suggested by Reddy et al (2018) for highredshift, low-mass galaxies, we use the SMC dust extinction curve (Gordon et al 2003) with A V values varying between 0.0 − 2.0. We fix the metallicity at 0.2 Z and the redshift at the spectroscopic value.…”