14-18 October 2019
T-Hotel Cagliari
Europe/Rome timezone

First Identification of 10-kpc Scale [CII] 158um Halos around Star-Forming Galaxies at z=5-7

18 Oct 2019, 11:35
T-Hotel Cagliari

T-Hotel Cagliari

Via Dei Giudicati, 66 | 09131 Cagliari | Sardinia, Italy


Dr Seiji Fujimoto


Contributed talk

We report the discovery of 10-kpc scale [CII] 158um halos surrounding star-forming galaxies in the early Universe. We choose deep ALMA data of 18 galaxies each with a star-formation rate of ~ 10-70 Msun with no signature of AGN whose [CII] lines are individually detected at z=5.153-7.142, and conduct stacking of the [CII] lines and dust-continuum in the uv-visibility plane. The radial profiles of the surface brightnesses show a 10-kpc scale [CII] halo at the 9.2sigma level significantly extended more than the HST stellar continuum data by a factor of ~5 on the exponential-profile scale length basis, as well as the dust continuum. We also compare the radial profiles of [CII] and Lya halos universally found in star-forming galaxies at this epoch, and find that the scale lengths agree within the 1sigma level. The existence of the extended [CII] halo is the evidence of outflow remnants in the early galaxies and suggest that the outflows may be dominated by cold-mode outflows, which challenges current galaxy evolution models.

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