The ALMA REBELS Survey: Average [C II] 158 μm Sizes of Star-forming Galaxies from z 7 to z 4

August 2022 • 2022ApJ...934..144F

Authors • Fudamoto, Y. • Smit, R. • Bowler, R. A. A. • Oesch, P. A. • Bouwens, R. • Stefanon, M. • Inami, H. • Endsley, R. • Gonzalez, V. • Schouws, S. • Stark, D. • Algera, H. S. B. • Aravena, M. • Barrufet, L. • da Cunha, E. • Dayal, P. • Ferrara, A. • Graziani, L. • Hodge, J. A. • Hygate, A. P. S. • Inoue, A. K. • Nanayakkara, T. • Pallottini, A. • Pizzati, E. • Schneider, R. • Sommovigo, L. • Sugahara, Y. • Topping, M. • van der Werf, P. • Bethermin, M. • Cassata, P. • Dessauges-Zavadsky, M. • Ibar, E. • Faisst, A. L. • Fujimoto, S. • Ginolfi, M. • Hathi, N. • Jones, G. C. • Pozzi, F. • Schaerer, D.

Abstract • We present the average [C II] 158 μm emission line sizes of UV-bright star-forming galaxies at z ~ 7. Our results are derived from a stacking analysis of [C II] 158 μm emission lines and dust continua observed by the Atacama Large Millimeter/submillimeter Array (ALMA), taking advantage of the large program Reionization Era Bright Emission Line Survey. We find that the average [C II] emission at z ~ 7 has an effective radius r _e of 2.2 ± 0.2 kpc. It is ≳2× larger than the dust continuum and the rest-frame UV emission, in agreement with recently reported measurements for z ≲ 6 galaxies. Additionally, we compared the average [C II] size with 4 < z < 6 galaxies observed by the ALMA Large Program to INvestigate [C II] at Early times (ALPINE). By analyzing [C II] sizes of 4 < z < 6 galaxies in two redshift bins, we find an average [C II] size of r _e = 2.2 ± 0.2 kpc and r _e = 2.5 ± 0.2 kpc for z ~ 5.5 and z ~ 4.5 galaxies, respectively. These measurements show that star-forming galaxies, on average, show no evolution in the size of the [C II] 158 μm emitting regions at redshift between z ~ 7 and z ~ 4. This finding suggests that the star-forming galaxies could be morphologically dominated by gas over a wide redshift range.

Links

• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ac7a47/pdf
• PREPRINT http://arxiv.org/abs/2206.01886
• DATA http://archive.eso.org/bin/ads2eso?2022ApJ...934..144F
• DATA https://telbib.eso.org/detail.php?bibcode=2022ApJ...934..144F
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fac7a47