Infrared Spectral Energy Distributions and Dust Masses of Sub-solar Metallicity Galaxies at z ∼2.3

Irene Shivaei, Gergö Popping, George Rieke, Naveen Reddy, Alexandra Pope, Robert Kennicutt, Bahram Mobasher, Alison Coil, Yoshinobu Fudamoto, Mariska Kriek, Jianwei Lyu, Pascal Oesch, Ryan Sanders, Alice Shapley, Brian Siana

Research output: Contribution to journalArticlepeer-review

Abstract

We present results from Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm continuum observations of a sample of 27 star-forming galaxies at z = 2.1-2.5 from the MOSFIRE Deep Evolution Field survey with metallicity and star formation rate measurements from optical emission lines. Using stacks of Spitzer, Herschel, and ALMA photometry (rest frame ∼8-400 μm), we examine the infrared (IR) spectral energy distributions (SED) of z ∼2.3 subsolar-metallicity (∼0.5 Z) luminous infrared galaxies (LIRGs). We find that the data agree well with an average template of higher-luminosity local low-metallicity dwarf galaxies (reduced χ 2 = 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ultraluminous IR galaxies, even in the most favorable case (with reduced χ 2 = 2.8), the templates are rejected at >98% confidence. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar-metallicity galaxies may result from different grain properties or a harder/more intense ionizing radiation field that increases the dust temperature. The obscured star formation rate (SFR) indicated by the far-IR emission of the subsolar-metallicity galaxies is only ∼60% of the total SFR, considerably lower than that of the local LIRGs with ∼96%-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data overestimate the Rayleigh-Jeans tail measurements by a factor of 2-20. These templates underestimate IR luminosities if fit to the observed ALMA fluxes by >0.4 dex. At a given stellar mass or metallicity, dust masses at z ∼2.3 are an order of magnitude higher than z ∼0. Given the predicted molecular gas fractions, the observed z ∼2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies with similar metallicities.

Original languageEnglish
Article number68
JournalAstrophysical Journal
Volume928
Issue number1
DOIs
Publication statusPublished - 2022 Mar 1

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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