NSF-BSF: The Physics of Multiphase Gas Streams feeding Galaxies from the Cosmic Web

Yale University, New Haven CT

Investigators

Abstract

Over the past two decades, a coherent picture of galaxy formation has emerged whereby gas flows into massive dark matter halos from the Intergalactic Medium (IGM) via a network of narrow filaments and sheets that together comprise the "cosmic web”. This gas accretion supplies fuel for star formation, sets the angular momentum and size of disk galaxies, and drives turbulence and disk instabilities. We cannot fully understand galaxy evolution without a detailed understanding of this accretion process. However, numerical simulations of this inflow are extremely challenging. This research team will address these shortcomings through an extended suite of cosmological magneto-hydrodynamical simulations designed to resolve the filaments and IGM to accurately model their evolution and explore the detailed physics of how galaxies are fed from their earliest stages of formation. This work will provide mentoring and training for two graduate students. The team will also create a cosmology module for Yale's Pathway to Science program and run a free two-week summer STEM program for high school students. The proposed simulations will resolve the multiphase structure of gas over all the relevant scales, from the Mpc-sized cosmic sheets and filaments to the dense clumps (tens of parsecs) of gas that form within the streams and the stream-fed disks. Such a comprehensive theoretical analysis promises to reshape the understanding of galaxy formation in a cosmological context as well as deepen our understanding of the physics of multiphase plasmas. It is also highly timely to aid in interpreting current and upcoming observational data of the gas around galaxies, Lyman-alpha blobs, the Lyman-alpha Forest, and metal-free Lyman limit systems. In addition, this study aims to improve the understanding of how high-z disk galaxies acquire their angular momentum and which mechanisms are responsible for triggering turbulence and maintaining violent instabilities. All simulations run as part of this study will be made publicly available. The team will also build analytic models that encapsulate their findings and elucidate the physics of galaxy formation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.