ALMA Observation of a z ≳ 10 Galaxy Candidate Discovered with JWST

Abstract

Abstract We report the observation by the Atacama Large Millimeter/submillimeter Array (ALMA) of a z ≳ 10 galaxy candidate (GHZ1) discovered from the GLASS–JWST Early Release Science Program. Our ALMA program aims to detect the [O iii] emission line at the rest-frame frequency 3393.0062 GHz (88.36 μm) and far-IR continuum emission with the spectral window setup seamlessly covering a 26.125 GHz frequency range (10.10 < z < 11.14). A total of 7 hr of on-source integration was employed, using four frequency settings to cover the full range (1.7 hr per setting), with 0.″7 angular resolution. No line or continuum is clearly detected, with 5σ upper limits on the line emission of 0.93 mJy beam−1 at 25 km s−1 channel−1 and on the continuum emission of 30 μJy beam−1. We report marginal spectral (at 225 km s−1 resolution) and continuum features (4.1σ and 2.6σ peak signal-to-noise ratio, respectively), within 0.″17 from the JWST position of GHZ1. This spectral feature implies z = 10.38 and needs to be verified with further observations. Assuming that the best estimate of photometric redshift ( z = 10.60 − 0.60 + 0.52 ) is correct, the model of the galaxy’s broadband spectral energy distribution for the 3σ upper limit of the continuum flux from GHZ1 suggests that GHZ1 has a small amount of dust (M d ≲ 104 M ⊙) at a high temperature (T d ≳ 90 K). The 5σ upper limit on the [O iii]88μm line luminosity and the inferred star formation rate of GHZ1 are consistent with the properties of low-metallicity dwarf galaxies. We also report serendipitous clear detections of six continuum sources at the locations of the JWST galaxy counterparts in the field.