ALMA [CII] detection of a redshift 7 lensed galaxy behind RXJ1347.1-1145
Maru\v{s}a Brada\v{c}, Diego Garcia-Appadoo, Kuang-Han Huang, Livia, Vallini, Emily Finney, Austin Hoag, Brian Lemaux, Kasper Schmidt, Tommaso, Treu, Chris Carilli, Mark Dijkstra, Andrea Ferrara, Adriano Fontana, Tucker, Jones, Russell Ryan, Jeff Wagg

TL;DR
This study reports the detection of the [CII] line in a gravitationally lensed galaxy at redshift 7, providing insights into its metallicity, feedback processes, and ionizing photon escape, with implications for early galaxy evolution.
Contribution
First detection of [CII] emission in a z=7 galaxy behind a lens, revealing lower luminosity and potential feedback effects compared to local galaxies.
Findings
[CII] luminosity is about 5 times fainter than other z~7 galaxies.
Small velocity offset suggests possible ionizing photon escape.
Low [CII] luminosity may be due to low metallicity or feedback effects.
Abstract
We present the results of ALMA spectroscopic follow-up of a Lyman- emitting galaxy behind the cluster RXJ1347-1145. We report the detection of [CII]158m line fully consistent with the Lyman- redshift and with the peak of the optical emission. Given the magnification of the intrinsic (corrected for lensing) luminosity of the [CII] line is , which is times fainter than other detections of galaxies. The result indicates that low in galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity off-set () between the Lyman- and [CII] line is unusual, and may be indicative of ionizing photons escaping.
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