The ALMA REBELS survey: the dust content of z ∼ 7 Lyman break galaxies. Issue 1 (3rd March 2022)

• Record Type: Journal Article
• Authors: Dayal, P; Ferrara, A; Sommovigo, L; Bouwens, R; Oesch, P A; Smit, R; Gonzalez, V; Schouws, S; Stefanon, M; Kobayashi, C; Bremer, J; Algera, H S B; Aravena, M; Bowler, R A A; da Cunha, E; Fudamoto, Y; Graziani, L; Hodge, J; Inami, H; De Looze, I; Pallottini, A; Riechers, D; Schneider, R; Stark, D; Endsley, R
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 512:Issue 1(2022)
• Page Start: 989
• Page End: 1002
• Publication Date: 2022-03-03
• Subjects: dust, extinction -- galaxies: evolution -- galaxies: high-redshift -- galaxies: ISM -- galaxies: luminosity function, mass function; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac537
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We include a fully coupled treatment of metal and dust enrichment into the Delphi semi-analytic model of galaxy formation to explain the dust content of 13 Lyman break galaxies (LBGs) detected by the Atacama Large millimetre Array (ALMA) REBELS Large Program at z ≃ 7. We find that the galaxy dust mass, M d, is regulated by the combination of Type II supernova dust production, astration, shock destruction, and ejection in outflows; grain growth (with a standard time-scale τ 0 = 30 Myr) plays a negligible role. The model predicts a dust-to-stellar mass ratio of $\sim 0.07\!-\!0.1{{\ \rm per\ cent}}$ and a UV-to-total star formation rate relation such that log(ψUV ) = −0.05 [log(ψ)] 2 + 0.86 log(ψ) − 0.05 (implying that 55–80 per cent of the star formation is obscured) for REBELS galaxies with stellar mass $M_* = 10^{9}\!-\!10^{10} \rm M_\odot$ . This relation reconciles the intrinsic UV luminosity of LBGs with their observed luminosity function at z = 7. However, 2 out of the 13 systems show dust-to-stellar mass ratios ($\sim 0.94\!-\!1.1{{\ \rm per\ cent}}$ ) that are up to 18 times larger than expected from the fiducial relation. Due to the physical coupling between dust and metal enrichment, even decreasing τ 0 to very low values (0.3 Myr) only increases the dust-to-stellar mass ratio by a factor of ∼2. Given that grain growth is not a viable explanation for such high observed ratios of the dust-to-stellar mass, we propose alternative solutions.