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Arxiv: Statistics for Galaxy Outflows at z\sim 6-9 with Imaging and Spectroscopic Signatures Identified with JWST/NIRCam and NIRSpec Data Published: 6/13/2023 8:40:39 PM Updated: 5/8/2024 7:54:21 AM

Paper abstract: We present statistics of z~ 6-9 galaxy outflows indicated byspatially-extended gas emission and broad lines. With a total of 61spectroscopically confirmed galaxies at z~ 6-9 in the JWST CEERS, GLASS,and ERO data, we find four galaxies with [O{\sc iii}]+H\beta ionized gasemission significantly extended beyond the kpc-scale stellar components on thebasis of the emission line images constructed by the subtraction of NIRCambroadband (line on/off-band) images. By comparison with low-z galaxies, thefraction of galaxies with the spatially extended gas, 4/18, at z~ 6-9 isan order of magnitude higher than those at z~ 0-1, which can be explainedby events triggered by frequent major mergers at high redshift. We alsoinvestigate medium- and high-resolution NIRSpec spectra of 30 galaxies atz~ 6-9, and identify five galaxies with broad (140-800 km s^{-1})lines in the [O{\sc iii}] forbidden line emission, suggestive of galaxyoutflows. One galaxy at z=6.38 shows both the spatially-extended gas emissionand the broad lines, while none of the galaxies with the spatially-extended gasemission or broad lines present a clear signature of AGN either in the linediagnostics or Type 1 AGN line broadening (>1000 km s^{-1}), which hintoutflows mainly driven by stellar feedback. The existence of galaxieswith/without spatially-extended gas emission or broad lines may be explained bydifferent viewing angles towards outflows, or that these are galaxies in theearly, late, post phases of galaxy outflows at high redshift, where therelatively large fractions of such galaxies indicate the longer-duration and/ormore-frequent outflows at the early cosmic epoch.