Probing star formation and ISM properties using galaxy disk inclination

III. Evolution in dust opacity and clumpiness between redshift 0.0 < z < 0.7 constrained from UV to NIR

¹ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
² Sterrenkundig Observatorium, Ghent University, Krijgslaan 281 – S9, 9000 Gent, Belgium
e-mail: stefan.stefananthonyvandergiessen@ugent.be
³ Dept. Fisica Teorica y del Cosmos, Universidad de Granada, Granada, Spain
⁴ International Centre for Radio Astronomy Research, The University of Western Australia, 7 Fairway, Crawley, WA 6009, Australia
⁵ Research School of Astronomy and Astrophysics, Australian National University, Mt Stromlo Observatory, Weston Creek, ACT 2611, Australia
⁶ Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
⁷ Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK
⁸ International Space Science Institute (ISSI), Hallerstrasse 6, 3012 Bern, Switzerland
⁹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁰ Max-Plank Institute for Nuclear Physics (MPIK), Saupfercheckweg 1, 69117 Heidelberg, Germany

Received: 15 October 2021
Accepted: 24 January 2022

Abstract

Attenuation by dust severely impacts our ability to obtain unbiased observations of galaxies, especially as the amount and wavelength dependence of the attenuation varies with the stellar mass M_*, inclination i, and other galaxy properties. In this study, we used the attenuation – inclination models in ultraviolet, optical, and near-infrared bands designed by Tuffs and collaborators to investigate the average global dust properties in galaxies as a function of M_*, the stellar mass surface density μ_*, the star-formation rate SFR, the specific star-formation rate sSFR, the star-formation main-sequence offset dMS, and the star-formation rate surface density Σ_SFR at redshifts z ∼ 0 and z ∼ 0.7. We used star-forming galaxies from the Sloan Digital Sky Survey (∼20 000) and Galaxy And Mass Assembly (∼2000) to form our low-z sample at 0.04 < z < 0.1 and star-forming galaxies from Cosmological Evolution Survey (∼2000) for the sample at 0.6 < z < 0.8. We found that galaxies at z ∼ 0.7 have a higher optical depth τ_B^f and clumpiness F than galaxies at z ∼ 0. The increase in F hints that the stars of z ∼ 0.7 galaxies are less likely to escape their birth cloud, which might indicate that the birth clouds are larger. We also found that τ_B^f increases with M_* and μ_*, independent of the sample and therefore redshift. We found no clear trends in τ_B^f or F with the SFR, which could imply that the dust mass distribution is independent of the SFR. In turn, this would imply that the balance of dust formation and destruction is independent of the SFR. Based on an analysis of the inclination dependence of the Balmer decrement, we found that reproducing the Balmer line emission requires not only a completely optically thick dust component associated with star-forming regions, as in the standard model, but an extra component of an optically thin dust within the birth clouds. This new component implies the existence of dust inside H II regions that attenuates the Balmer emission before it escapes through gaps in the birth cloud and we found it is more important in high-mass galaxies. These results will inform our understanding of dust formation and dust geometry in star-forming galaxies across redshift.