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ALMA reveals extended cool gas and hot ionized outflows in a typical star-forming galaxy at z=7.13

Presentation #241.23 in the session Evolution of Galaxies — iPoster Session.

Published onJun 29, 2022
ALMA reveals extended cool gas and hot ionized outflows in a typical star-forming galaxy at z=7.13

We present spatially-resolved morphological properties of [CII] 158 μm, [OIII] 88 μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy at z = 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius of r ~ 12 kpc. Using multi-band rest-frame far-infrared (FIR) continuum data ranging from 52–400 μm, we find an average dust temperature and emissivity index of T = 41 (+17,-14) K and β = 1.7 (+1.1,-0.7), respectively, across the galaxy. By fixing β, we measure the spatially-resolved dust temperature which peaks at the galaxy center with ~50 K and cools to larger distances. We map the star-formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1 Msun/yr with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the local L[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII] with significant residuals (~5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggests a possible origin of the [CII] halo from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the high [OIII]/[CII] ratios recently reported in z > 6 galaxies.

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