0 Assigned ID: 862 ----- Attempting Submission 1 (Fri Apr 05 22:17:56 GMT 2019) ----- HST Phase I Proposal 862 (HST_Proposal_2019__Subgrid_CGM_Model (SUBMITTED).pdf.apt) successfully submitted. Receipt: # 862-1 ----- Attempting Submission 2 (Fri Apr 05 22:38:44 GMT 2019) ----- The majority of galactic baryons reside outside of the galactic disk in the diffuse gas known as the circumgalactic medium (CGM). While state-of-the art simulations excel at reproducing properties of the galactic disk, they struggle to reproduce the observational characteristics of the CGM, most notably the observed column densities and kinematics of cool (T ~ 10^4 K) gas. The survival of cool gas in the CGM is governed by physical processes that are unresolved in existing simulations. Recent work has demonstrated how increasing halo resolution leads to qualitatively different abundances and behavior of the CGM, but this behavior is not predicted to converge until sub-parsec scales are reached. Even with adaptive mesh refinement, fully resolving the CGM at these scales requires computational resources not expected to exist for several decades. We propose developing the first subgrid model to track the unresolved cool phase of the CGM in cosmological hydrodynamics simulations of galaxy evolution. The unique strength of this model is that it requires no tuning, as it derives from robust representations of the underlying small-scale physics. Our model and its implementation in two popular astrophysical hydrodynamics codes, Enzo and Gizmo, will be released publicly to help jump start use of this transformational method by the community. Lastly, the model will be employed on large-scale cosmological zoom simulations to address key science drivers of how the cool gas of the CGM behaves, where metals go, and how galaxies quench. PI Cameron Hummels is a postdoctoral fellow at Caltech and expert in computational methods of modeling galaxy evolution, the circumgalactic medium (CGM), and making comparisons between simulated datasets and observations. PI Hummels has been PI on two successful HST theory proposals and author on ten CGM papers, five involving HST/COS data. He has wide-ranging experience modifying, executing, and analyzing the two simulation codes involved in this proposal: Enzo and Gizmo. PI Hummels has been a developer on the Enzo code for over a decade, having worked to expand the subgrid models for stellar feedback, and he is leading the effort to compare the FIRE simulations, using the Gizmo code, to the COS-Halos CGM observational dataset. Additionally, PI Hummels is the main developer for the Trident synthetic spectra code, the primary method for analyzing computational CGM datasets in the astrophysical community. Co-PI Iryna Butsky is a PhD student at the University of Washington and is the Co-I on a successful HST Theory proposal with Tom Quinn and Jessica Werk. In the last two years, she has implemented cosmic rays as a second fluid in both the Enzo and ChaNGa simulation codes, which has prepared her to develop and implement the proposed second-fluid cold gas model in Enzo and Gizmo. Co-PI Butsky also has extensive experience comparing simulations of the CGM with observations using the Trident analysis package. Co-I Jessica Werk has been using COS, the data with which we will compare our theoretical results, since Cycle 17, when it first came online. She is the PI on 2 previous successful HST-GO proposals, is a first author on 5 papers that focus on results from COS data, and a co-author on 25+ publications that present results based on HST/COS data. She is primarily an observer (spectroscopist) who seeks to understand the intricate relationship between galaxies and their extended gaseous envelopes. In addition, she works closely with theorists to interpret observational data. Her experience reducing and analyzing COS absorption line spectroscopy, from both QSO and stellar sources, is extensive. In particular, her experience using CLOUDY, a full radiative-transfer code, to determine the physical properties of the absorption features will be highly useful for the proposed analysis. Co-I Phil Hopkins has broad experience in all matter of computational modeling of galaxies and their environments and has been recognized with many awards including the AAS Helen B. Warner Prize. Co-I Hopkins is the primary developer of the Gizmo hydrodynamics code and FIRE simulation effort. He has already implemented subgrid feedback models as well as a second fluid implementation of cosmic rays in Gizmo, making him a unique resource to assist in creating the proposed second-fluid subgrid model. In addition, Co-I Hopkins has already run many high-resolution idealized CGM simulations in Gizmo for use in the proposed work. Co-I Britton Smith is an expert in theoretical galaxy evolution and the thermal evolution of cosmic gas. He is one of the primary developers of the Enzo hydrodynamics code, the primary author of the Grackle cooling module, and a major contributor to several open-source astrophysical code projects including the Trident analysis code. Co-I Thomas Quinn has decades of experience in simulating galaxy formation and has participated in the development of high performance simulation codes. This includes the supervision of graduate students as they developed feedback models for supernovae and AGN. He is a co-author on 200+ publications, most of which involve the analysis of large simulations. Co-I Quinn also acts as co-PI Butsky's thesis advisor. Galaxies and the IGM 0 Legacy false false true true false SUPPORTED