New Methods for Simulating Astrophysical Ices in the JWST-Era*

One of the most surprising findings of astrochemistry has been the variety and comparative complexity of the organic molecules detected in interstellar environments. The dominant theory regarding how these complex organic molecules (COM) came to be has been that they form from radicals trapped in dust-grain ice mantles, which begin to diffuse more efficiently as a collapsing cloud heats up. Over the last decade, though, the increasingly frequent detections of COMs in cold molecular clouds has led to questions regarding whether this thermal diffusion-dominated picture of their formation tells the whole story.

In the lab, COMs are readily produced within ices, at temperatures as low as 5 K, upon irradiation by, e.g., energetic ions, electrons, or UV photons - all of which undoubtedly bombard cosmic ices to varying degrees. However, incorporating the physical and chemical effects that lead to COM formation under these conditions has been challenging, due in part to the variety and complexity of the underlying processes. Over the last several years, we have endeavored to rectify this deficiency in astrochemical modeling by deriving new methods for simulating (a) cosmic ray-driven radiation chemistry, (b) the reactions of reactive species within ices, and most recently, (c) solid-phase UV photochemistry. These three areas will be the focus of this talk, as well as the revised picture of the evolution of COMs in the ISM that is suggested by our preliminary results.