Earlier this year physics grad student Yu-Hsuan “Eltha” Teng was awarded a prestigious scholarship from the government of Taiwan. It is called the "Government Scholarship to Study Abroad" (GSSA) and is an honor given to only a small number of Taiwanese students pursuing PhD degrees outside of Taiwan. The scholarship comes from the Ministry of Education of Taiwan.
Eltha's current research with Prof. Karin Sandstrom is focused on the molecular gas and star formation in nearby galaxy centers. Stars are born in molecular gas, and galaxy centers frequently host the most active star formation in disk galaxies due to gas concentrations driven by stellar bars or spiral arms. Feedback from active galactic nuclei or nuclear starburst can also affect the physical conditions in some galaxy centers. Therefore, galaxy centers tend to have very different molecular gas properties from those in the disks, and thus they are ideal test beds for understanding the environment and mechanism of star formation in galaxies. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observe nearby galaxy centers at multiple rotational transitions of CO, 13CO, and C18O molecules on 100 pc scales.
Such high resolution data reveal cloud-scale variation of molecular gas properties, and also allow us to investigate their relationship with the CO-to-H2 conversion factor, which is one of the most critical parameters for inferring the molecular gas mass. Our thorough analysis on the galaxy NGC 3351 have shown that dynamical effects and/or low optical depth CO emission from bar-driven inflows can cause significant variation of the conversion factor in barred galaxy centers, and the results have been accepted for publication in The Astrophysical Journal.
Currently, we are extending our analysis to other nearby galaxies, aiming to identify the key diagnostics for determining molecular gas mass and develop a universal prescription that can be applied across large galaxy samples in future studies.