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

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.
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Contributor : Olivier Hauss Connect in order to contact the contributor
Submitted on : Monday, August 29, 2022 - 6:05:05 PM
Last modification on : Tuesday, August 30, 2022 - 3:31:57 AM
Long-term archiving on: : Wednesday, November 30, 2022 - 7:06:35 PM


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Y. Fudamoto, R. Smit, R. A. A. Bowler, P. A. Oesch, R. Bouwens, et al.. The ALMA REBELS Survey: Average [C II] 158 μm Sizes of Star-forming Galaxies from z 7 to z 4. The Astrophysical Journal, 2022, 934, ⟨10.3847/1538-4357/ac7a47⟩. ⟨insu-03763628⟩



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