Infrared Spectral Energy Distributions and Dust Masses of Sub-solar Metallicity Galaxies at z similar to 2.3
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- Shivaei_2022_ApJ_928_68
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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 similar to 8-400 mu m), we examine the infrared (IR) spectral energy distributions (SED) of z similar to 2.3 subsolar-metallicity (similar to 0.5 Z (circle dot)) luminous infrared galaxies (LIRGs). We find that the data agree well with an average template of higher-luminosity local low-metallicity dwarf galaxies (reduced chi (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 chi (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 similar to 60% of the total SFR, considerably lower than that of the local LIRGs with similar to 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 similar to 2.3 are an order of magnitude higher than z similar to 0. Given the predicted molecular gas fractions, the observed z similar to 2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies with similar metallicities.
Originalsprog | Engelsk |
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Artikelnummer | 68 |
Tidsskrift | Astrophysical Journal |
Vol/bind | 928 |
Udgave nummer | 1 |
Antal sider | 26 |
ISSN | 0004-637X |
DOI | |
Status | Udgivet - 1 mar. 2022 |
ID: 302540579