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arXiv · 1610.02099

ALMA [CII] detection of a redshift 7 lensed galaxy behind RXJ1347.1-1145

Maruša Bradač·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
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Abstract

We present the results of ALMA spectroscopic follow-up of a $z=6.765$ Lyman-$\alpha$ emitting galaxy behind the cluster RXJ1347-1145. We report the detection of [CII]158$\mu$m line fully consistent with the Lyman-$\alpha$ redshift and with the peak of the optical emission. Given the magnification of $\mu=5.0 \pm 0.3$ the intrinsic (corrected for lensing) luminosity of the [CII] line is $L_{[CII]} =1.4^{+0.2}_{-0.3} \times 10^7L_{\odot}$, which is ${\sim}5$ times fainter than other detections of $z\sim 7$ galaxies. The result indicates that low $L_{[CII]}$ in $z\sim 7$ galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity off-set ($\Delta v = 20_{-40}^{+140} \rm km/s$) between the Lyman-$\alpha$ and [CII] line is unusual, and may be indicative of ionizing photons escaping.

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Maruša Bradač, 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. 2016-10-06. ALMA [CII] detection of a redshift 7 lensed galaxy behind RXJ1347.1-1145. https://doi.org/10.3847/2041-8213/836/1/l2

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