Characterizing Density and Potential Fluctuations of the Interstellar Medium

Speaker: Shaunak Modak (Princeton) In Person and zoom 

Zoom info: https://stanford.zoom.us/my/sihanyuan?pwd=QnpsUHZWWGJ2ekVYWmZVL3BmM0gzZ…

The interstellar medium (ISM) plays an important role in sculpting the structure of our Galaxy: in addition to being the birthplace of stars, ISM substructures have the capacity to significantly perturb stellar orbits. Presently, despite their far-reaching influence in stellar dynamics, these fluctuations have only been studied with models that do not capture realistic properties of the ISM: analytic models (e.g. those based on isotropically distributed spherical "clouds") are overly idealized, while global simulations (e.g. MHD coupled to N-body) can be under-resolved and lack key ISM physics. In this talk, I will present a quantitative characterization of these fluctuations in the state-of-the-art TIGRESS-NCR MHD simulations, which include galactic shear, self-consistent star formation and feedback, nonequilibrium chemistry, and cooling, resolving scales down to 2 pc. I will also highlight key differences between the dynamical effects of these fluctuations and those assumed in prevailing models. Ultimately, our results demonstrate the importance of incorporating a realistic treatment of the ISM in dynamical studies of galactic disks, and provide convenient parametrizations for doing so.