Dust Attenuation Curves at z ~ 0.8 from LEGA-C:Precise Constraints on the Slope and 2175Å Bump Strength

Barisic, Ivana and Pacifici, Camila and Wel, Arjen van der and Straatman, Caroline and Bell, Eric F. and Bezanson, Rachel and Brammer, Gabriel and D'Eugenio, Francesco and Franx, Marijn and Houdt, Josha van and Maseda, Michael V. and Muzzin, Adam and Sobral, David and Wu, Po-Feng (2020) Dust Attenuation Curves at z ~ 0.8 from LEGA-C:Precise Constraints on the Slope and 2175Å Bump Strength. The Astrophysical Journal, 903 (2). ISSN 0004-637X

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Abstract

We present a novel approach to measure the attenuation curves of 485 individual star-forming galaxies with M* > 1010 M⊙ based on deep optical spectra from the VLT/VIMOS LEGA-C survey and multi-band photometry in the COSMOS field. Most importantly, we find that the attenuation curves in the rest-frame 3000-4500 Å range are typically almost twice as steep as the Milky Way, LMC, SMC, and Calzetti attenuation curves, which is in agreement with recent studies of the integrated light of present-day galaxies. The attenuation at 4500 Å and the slope strongly correlate with the galaxy inclination: face-on galaxies show less attenuation and steeper curves compared to edge-on galaxies, suggesting that geometric effects dominate observed variations in attenuation. Our new method produces 2175 Å UV bump detections for 260 individual galaxies. Even though obvious correlations between UV bump strength and global galaxy properties are absent, strong UV bumps are most often seen in face-on, lower-mass galaxies (10 < log10(M*/M⊙) < 10.5) with low overall attenuation. Finally, we produce a typical attenuation curve for star-forming galaxies at z ~ 0.8; this prescription represents the effect of dust on the integrated spectral energy distributions of high-redshift galaxies more accurately than commonly used attenuation laws.