The ALMA REBELS survey: obscured star formation in massi v e Lyman-break galaxies at z = 4-8 revealed by the IRX-βand M*relations

R. A.A. Bowler*, H. Inami, L. Sommovigo, R. Smit, H. S.B. Algera, M. Aravena, L. Barrufet, R. Bouwens, E. da Cunha, F. Cullen, P. Dayal, I. De Looze, J. S. Dunlop, Y. Fudamoto, V. Mauerhofer, R. J. McLure, M. Stefanon, R. Schneider, A. Ferrara, L. GrazianiJ. A. Hodge, T. Nanayakkara, M. Palla, S. Schouws, D. P. Stark, P. P. van der Werf

*Corresponding author voor dit werk

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7 Citaten (Scopus)
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Samenvatting

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.

Originele taal-2English
Pagina's (van-tot)5808-5828
Aantal pagina's21
TijdschriftMonthly Notices of the Royal Astronomical Society
Volume527
Nummer van het tijdschrift3
DOI's
StatusPublished - jan.-2024

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