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 language | English |
|---|---|
| Article number | 68 |
| Journal | Astrophysical Journal |
| Volume | 928 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 1 2022 |
Bibliographical note
Publisher Copyright:© 2022. The Author(s). Published by the American Astronomical Society.
Funding
We thank the referee for a very constructive review. We thank Luke Maud from the European ALMA Regional Center at the European Southern Observatory (ESO) for valuable discussions and his help with running the ALMA calibration and imaging pipeline. We thank Loreto Munoz and Ryan Loomis at the North American Alma Science Center for valuable input on image construction and flux measurements of the ALMA data. We also thank Tanio Díaz-Santos for providing the GOALS survey data catalogs. Support for this work was provided by NASA through the NASA Hubble Fellowship grant #HST-HF2-51420, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555, to IS. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2019.1.01142.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. P.A.O. acknowledges support from the Swiss National Science Foundation through the SNSF Professorship grant No. 190079. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant No. 140. Y.F. further acknowledges support from NAOJ ALMA Scientific Research grant No. 2020-16B Funding for the MOSDEF survey was provided by NSF AAG grant Nos. AST-1312780, 1312547, 1312764, and 1313171 and archival grant No. AR-13907, provided by NASA through a grant from the Space Telescope Science Institute. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We are grateful to the MOSFIRE instrument team for building this powerful instrument, and to Marc Kassis at the Keck Observatory for his many valuable contributions to the execution of the MOSDEF survey. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
| Funders | Funder number |
|---|---|
| National Science Foundation (NSF) | 1312764, 1313171, 1312547, AR-13907, AST-1312780 |
| National Aeronautics and Space Administration | #HST-HF2-51420 |
| W. M. Keck Foundation | |
| Space Telescope Science Institute | NAS5-26555 |
| Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung | 190079 |
| Danmarks Grundforskningsfond | 140 |
| National Institutes of Natural Sciences, National Astronomical Observatory of Japan | 2020-16B |
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science