Aims. We aim to quantify the relation between the dust-to-gas mass ratio (DTG) and gas-phase metallicity of z = 2.1-2.5 luminous galaxies and contrast this high-redshift relation against analogous constraints at z = 0. Methods. We present a sample of ten star-forming main-sequence galaxies in the redshift range 2.1 < z < 2.5 with rest-optical emission-line information available from the MOSDEF survey and with ALMA 1.2 millimetre and CO J = 3-2 follow-up observations. The galaxies have stellar masses ranging from 1010.3 to 1010.6 M? and cover a range in star-formation rate from 35 to 145 M? yr-1. We calculated the gas-phase oxygen abundance of these galaxies from rest-optical nebular emission lines (8.4 < 12+log (O=H) < 8.8, corresponding to 0.5..1.25 Z?). We estimated the dust and H2 masses of the galaxies (using a metallicity-dependent CO-to-H2 conversion factor) from the 1.2mm and CO J = 3..2 observations, respectively, from which we estimated a DTG. Results. We find that the galaxies in this sample follow the trends already observed between CO line luminosity and dust-continuum luminosity from z = 0 to z = 3, extending such trends to fainter galaxies at 2.1 < z < 2.5 than observed to date. We find no second-order metallicity dependence in the CO - dust-continuum luminosity relation for the galaxies presented in this work. The DTGs of main-sequence galaxies at 2.1 < z < 2.5 are consistent with an increase in the DTG with gas-phase metallicity. The metallicity dependence of the DTG is driven by the metallicity dependence of the CO-to-H2 conversion factor. Galaxies at z = 2.1-2.5 are furthermore consistent with the DTG-metallicity relation found at z = 0 (i.e. with no significant evolution), providing relevant constraints for galaxy formation models. These results furthermore imply that the metallicity of galaxies should be taken into account when estimating cold-gas masses from dust-continuum emission, which is especially relevant when studying metal-poor low-mass or high-redshift galaxies.
|Journal||Astronomy and Astrophysics|
|State||Published - Feb 1 2023|
Bibliographical noteFunding Information:
We thank Leindert Boogaard, Melanie Kaasinen and Bahram Mobasher for useful discussions and feedback. We thank the referee for constructive comments. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2019.1.01142.S and ADS/JAO.ALMA#2018.1.01128.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. We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, 1313171, 2009313, and 2009085, grant AR-13907 from the Space Telescope Science Institute, grant NNX16AF54G from the NASA ADAP program. Support for this work was also provided through the NASA Hubble Fellowship grant #HST-HF2-51469.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.
© 2023 The Authors.
- Galaxies: evolution
- Galaxies: high-redshift
- Galaxies: ISM
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science