Caltech/IPAC Lunch Seminar

The ISM structures, such as molecular clouds and filaments, and their evolution impact galactic gas dynamics, cooling and evolutionary timescales, and trigger of star formation. Recent studies emphasize the very rapid formation and destruction of molecular clouds by feedback. However, this picture is inconsistent with the observed deficiency of HI gas in their disks, the expected end product of the rapid evolution. I will point out the shortcomings of the feedback-driven short cloud lifetime arguments, and revisit the framework in which ISM evolution is primarily controlled by galactic dynamics. Using ALMA observations of the MW-like spiral galaxy M83, I will show that molecular clouds and their physical conditions evolve in concert with large-scale galactic structures. They coagulate and fragment through the stirring in galactic dynamics, rather than feedback alone. I will also discuss future prospects, including the upcoming JWST survey of embedded star formation across the full disk of M83.