A Bit of Both: New Insight from ALMA and JWST on the Triggering of Star Formation in Dusty Star-Forming Galaxies at Cosmic Noon

Chian-Chou Chen (TC)^1*, Cheng-Lin Liao^2,1

¹Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan
²Graduate Institute of Astrophysics, National Taiwan University, Taipei, Taiwan

* Presenter:Chian-Chou Chen (TC), email:ccchen@asiaa.sinica.edu.tw

Compared to the Milky Way, Submillimeter galaxies (SMGs) are massive dusty star-forming galaxies that are ten times more massive and more than 100 times more active in star formation. SMGs are found to be most prevalent at a time when the rate of mass assembly of the Universe is at its peak, during the epoch so called the cosmic noon (z~1-3), and evidence suggest that they are likely progenitors of present-day massive ellipticals. Despite their important role in galaxy formation theory, models have struggled to reproduce basic properties of SMGs, and one outstanding issue is how their extensive star formation is triggered. In this talk I plan to bring new insights into this longstanding issue based on our recent observational studies using ALMA and JWST. In particular, I will show that, based on ALMA, SMGs have scaling relations consistent with those of typical star-forming galaxies on the main sequence, where these relations are based on key physical parameters such as gas fraction, depletion time, and specific star formation rates. On the other hand, based on JWST, the stellar morphologies of SMGs show features mimicking galactic bars, spiral arms, and tidal remnants. Together, our results suggest that SMGs could be undergoing dynamical interactions such as mergers, although their star formation is likely governed by Toomre's stability criterion.

Keywords: Galaxy formation, Submillimeter galaxies, Star formation , High-redshift galaxies, Galaxy structure