Title: "Chemical Links among NH2CHO, HNCO, and H2CO in Hot Core Regions"
Formamide (NH2CHO) is the simplest possible amid and contains a peptide bond that connects amino acids to form proteins. Then, it is important for understanding the formation processes of biological molecules to reveal the chemistry of such a simple amide. We have analyzed ALMA Band 6 data toward 30 high-mass star-forming regions containing hot core(s). We have identified a total of 44 hot cores and investigated chemical links among NH2CHO, HNCO, and H2CO using a partial correlation test. Strong correlation coefficients have been derived for pairs of NH2CHO-HNCO and NH2CHO-H2CO, which means that they are chemically linked. Our chemical simulation can reproduce the observational results, which enables us to reveal their gas-phase chemical links.
Title: "Initial results of commissioning observations in 2019 with Band 4 Receiver (B4R) on the LMT 50m telescope"
We have been working on commissioning observations with the B4R receiver on the LMT 50m telescope. Unfortunately, we could not work at the LMT site during this visit, but we plan to update the B4R system. In this presentation, I'll talk about the update plan of the B4R system and the initial results of mapping observations toward the Orion KL region obtained in the last commissioning in November 2019. Various complex organic molecules(COMs) have been detected in this region, and I have analyzed the chemical composition and distribution.
Title: "Bright Extragalactic ALMA Redshift Survey (BEARS): Gas physical properties of the bright Herschel-selected galaxies at high-redshift"
We present Atacama Large Millimetre/submillimetre Array (ALMA) Bands 3 and 4 observations of 85 high-redshift 500 μm sources selected from the Herschel Astrophysical Terahertz Large Area Survey with the primary goal of identifying their spectroscopic redshifts. Through the detections of CO, [C I], or H2O emission lines, we have determined reliable spectroscopic redshifts for 71 ALMA continuum sources. We created a deep stacked spectrum spanning 220 to 890 GHz at rest-frame frequencies, and we can identify the faint lines such as HCN(4–3).
Stacked results and most of our targets are consistent with the mean CO line ratios for Planck-selected lensed dusty star-forming galaxies shown by Harrington et al. (2021). This result means both galaxy populations have similar gas conditions. Using [C I] (3P1 ‒ 3P0) and CO emission lines as a tracer of molecular gas mass, we investigate the Schmidt-Kennicutt relation and compare it with previous works. We find that our galaxies are not simply scaled-up versions of the normal star-forming systems although have slightly longer depletion time scales than other submillimetre-selected galaxies. Our sources could be biased to bright CO or [CI] luminous, i.e. large amount of molecular gas, however, they could have more extended gas.