ALMA detection of extended [CII] emission in Himiko at z=6.6 [GA]

Himiko is one of the most luminous Ly{\alpha} emitters at z = 6.595. It has three star forming clumps detected in the rest-frame UV, with a total SFR = 20 M$\odot$/yr. We report the ALMA detection of the [CII]158$\mu$m line emission in this galaxy with a significance of 9$\sigma$. The total [CII] luminosity (L[CII]= (1.2$\pm$0.2)$\times$10$^{8}$ L${\odot}$) is fully consistent with the local L[CII]-SFR relation. The ALMA high-angular resolution reveals that the [CII] emission is made of two distinct components. The brightest [CII] clump is extended over 4 kpc and is located on the peak of the Ly{\alpha} nebula, which is spatially offset by 1 kpc relative to the brightest UV clump. The second [CII] component is spatially unresolved (size $<$2 kpc) and coincident with one of the three UV clumps. While the latter component is consitent with the local L[CII]-SFR relation, the other components are scattered above and below the local relation. We shortly discuss the possible origin of the [CII] components and their relation with the star forming clumps traced by the UV emission.

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S. Carniani, R. Maiolino, R. Smit, et. al.
Thu, 7 Dec 17

Comments: 6 pages, 3 figures, 2 tables; submitted to ApJL