# University of Hertfordshire

## The ALMA REBELS Survey: the dust content of $z \sim 7$ Lyman Break Galaxies

Research output: Contribution to journalArticlepeer-review

### Documents

• 2202.11118v1

Accepted author manuscript, 866 KB, PDF document

• P. Dayal
• A. Ferrara
• L. Sommovigo
• R. Bouwens
• P. A. Oesch
• R. Smit
• V. Gonzalez
• S. Schouws
• M. Stefanon
• J. Bremer
• H. S. B. Algera
• M. Aravena
• R. A. A. Bowler
• E. da Cunha
• Y. Fudamoto
• L. Graziani
• J. Hodge
• H. Inami
• I. De Looze
• A. Pallottini
• D. Riechers
• R. Schneider
• D. Stark
• R. Endsley
Original language English Monthly Notices of the Royal Astronomical Society https://doi.org/10.1093/mnras/stac537 Published - 22 Feb 2022

### 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 $z\simeq 7$. We find that the galaxy dust mass, $M_d$, is regulated by the combination of SNII dust production, astration, shock destruction, and ejection in outflows; grain growth (with a standard timescale $\tau_0= 30$ Myr) plays a negligible role. The model predicts a dust-to-stellar mass ratio of $\sim 0.07-0.1\%$ and a UV-to-total star formation rate relation such that $log (\psi_{\rm UV}) = -0.05 ~[log (\psi)]^{2} + 0.86 ~log(\psi) -0.05$ (implying that 55-80\% of the star formation is obscured) for REBELS galaxies with stellar mass $M_* = 10^{9-10} M_\odot$. 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 ($\sim 0.94-1.1\%$) 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 $\tau_0$ to very low values (0.3 Myr) only increases the dust-to-stellar mass ratio by a factor $\sim 2$. Given that grain growth is not a viable explanation for such high observed ratios of the dust-to-stellar mass, we propose alternative solutions.

### Notes

Accepted to MNRAS

ID: 27087134