The ALMA REBELS survey: obscured star formation in massive Lyman-break galaxies at z = 4-8 revealed by the IRX-β and M*relations

Bowler, RAA, Inami, H, Sommovigo, L, Smit, R ORCID: 0000-0001-8034-7802, Algera, HSB, Aravena, M, Barrufet, L, Bouwens, R, da Cunha, E, Cullen, F, Dayal, P, De Looze, I, Dunlop, JS, Fudamoto, Y, Mauerhofer, V, McLure, RJ, Stefanon, M, Schneider, R, Ferrara, A, Graziani, L et al (2023) The ALMA REBELS survey: obscured star formation in massive Lyman-break galaxies at z = 4-8 revealed by the IRX-β and M*relations. Monthly Notices of the Royal Astronomical Society, 527 (3). pp. 5808-5828. ISSN 0035-8711

Preview

Text The ALMA REBELS survey obscured star formation in massive Lyman-break galaxies at z= 4–8 revealed by the IRX–β and M⋆ relations.pdf - Published Version Available under License Creative Commons Attribution. Download (2MB) | Preview

Abstract

We investigate the degree of dust obscured star formation in 49 massive (log 10 ( M*/M ⊙) > 9) Lyman-break galaxies (LBGs) at z = 6.5-8 observed as part of the Atacama Large Millimeter/submillimeter Array (ALMA) Reionization Era Bright Emission Line Surv e y (REBELS) large program. By creating deep stacks of the photometric data and the REBELS ALMA measurements we determine the average rest-frame ultraviolet (UV), optical, and far-infrared (FIR) properties which reveal a significant fraction ( f obs = 0.4-0.7) of obscured star formation, consistent with previous studies. From measurements of the rest-frame UV slope, we find that the brightest LBGs at these redshifts show bluer ( β≃ -2.2) colours than expected from an extrapolation of the colour-magnitude relation found at fainter magnitudes. Assuming a modified blackbody spectral energy distribution (SED) in the FIR (with dust temperature of T d = 46 K and βd = 2.0), we find that the REBELS sources are in agreement with the local 'Calzetti-like' starburst Infrared-excess (IRX)-βrelation. By re-analysing the data available for 108 galaxies at z ≃ 4-6 from the ALMA Large Program to Investigate C + at Early Times (ALPINE) using a consistent methodology and assumed FIR SED, we show that from z ≃ 4-8, massive galaxies selected in the rest-frame UV have no appreciable evolution in their derived IRX-βrelation. When comparing the IRX-M*relation derived from the combined ALPINE and REBELS sample to relations established at z < 4, we find a deficit in the IRX, indicating that at z > 4 the proportion of obscured star formation is lower by a factor of ≳3 at a given a M*. Our IRX-βresults are in good agreement with the high-redshift predictions of simulations and semi-analytic models for z ≃ 7 galaxies with similar stellar masses and star formation rates.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	15 November 2023
Date of first compliant Open Access:	22 January 2024
Date Deposited:	22 Jan 2024 11:21
Last Modified:	04 Jul 2025 14:30
DOI or ID number:	10.1093/mnras/stad3578
URI:	https://researchonline.ljmu.ac.uk/id/eprint/22422

View Item