The MOSDEF Survey: The Variation of the Dust Attenuation Curve with Metallicity

Irene Shivaei, Naveen Reddy, George Rieke, Alice Shapley, Mariska Kriek, Andrew Battisti, Bahram Mobasher, Ryan Sanders, Tara Fetherolf, Mojegan Azadi, Alison L. Coil, William R. Freeman, Laura De Groot, Gene Leung, Sedona H. Price, Brian Siana, Tom Zick

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

We derive a UV-optical stellar dust attenuation curve of galaxies at z = 1.4-2.6 as a function of gas-phase metallicity. We use a sample of 218 star-forming galaxies, excluding those with very young or heavily obscured star formation, from the MOSFIRE Deep Evolution Field survey with Hα, Hβ, and [N ii]λ 6585 spectroscopic measurements. We constrain the shape of the attenuation curve by comparing the average flux densities of galaxies sorted into bins of dust obscuration using Balmer decrements, i.e., Hα-to-Hβ luminosities. The average attenuation curve for the high-metallicity sample (12 + log(O H) > 8.5, corresponding to M∗ ≳ 1010.4 M⊙) has a shallow slope, identical to that of the Calzetti local starburst curve, and a significant UV 2175 Å extinction bump that is ∼0.5× the strength of the Milky Way bump. On the other hand, the average attenuation curve of the low-metallicity sample (12 + log(O H) ∼ 8.2 - 8.5) has a steeper slope similar to that of the SMC curve, only consistent with the Calzetti slope at the 3σ level. The UV bump is not detected in the low-metallicity curve, indicating the relative lack of the small dust grains causing the bump at low metallicities. Furthermore, we find that on average the nebular reddening (E(B - V)) is a factor of 2 times larger than that of the stellar continuum for galaxies with low metallicities, while the nebular and stellar reddening are similar for galaxies with higher metallicities. The latter is likely due to a high surface density of dusty clouds embedding the star-forming regions but also reddening the continuum in the high-metallicity galaxies.

Original languageEnglish (US)
Article number117
JournalAstrophysical Journal
Volume899
Issue number2
DOIs
StatePublished - Aug 20 2020

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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