A preview of the ALMA WSU: prospects of the wide-band spectral observation of high-z galaxies

One of many benefits from ALMA WSU is efficient spectral line observation of high-z galaxies. In this talk, I will provide the analysis result of the two recent cycle 9 ALMA DDT programs that observed JWST discovered z>10 galaxy candidates, GHZ1 and GHZ2. Due to the design of the observing program searching for the redshifted [OIII] emission line, the observing blocks have 26-30 GHz bandwidth in band 6 with 4 spectral tunings, which is close to the ALMA WSU in band 6 with one spectral tuning. Although no significant emission is detected from the proposed z>10 targets, the observed data includes `serendipitous' multiple significant line emissions from the locations of other `intermediate redshift' JWST galaxies in the target field. Given the similarity of spectral bandwidth, the resulting ALMA data from these programs shows the promises of ALMA WSU to observe high-z galaxies with serendipitously detected multiple lines in a single spectral tuning and also challenges us to robustly identify the detected FIR ISM cooling lines from galaxies in a wide range of redshifts.