Computational Astrophysics: Galaxy Formation

Current simulations that attempt to explicitly resolve the multi-phase interstellar medium (ISM) and stellar feedback are typically set up with conditions that are representative of local disk galaxies like our Milky Way and do not incorporate a cosmological context of inflowing and outflowing material. This project seeks to develop new techniques to simulate star formation and understand how it works in environments very different from our local solar neighborhood, exploiting the common physics operating in all of these systems. These environments span the galactic center to the outskirts of low surface brightness galaxies, superstar clusters to globular clusters, massive dusty starburst galaxies to ultra-faint dwarf galaxies, protocluster galaxies to nearby jellyfish galaxies, and galaxies at cosmic dawn to nearby green peas. We plan to develop new analytic models and new simulation techniques to address these questions, using both idealized/controlled setups and well as cosmological initial conditions.

Supermassive black holes (SMBH) play a key role in regulating galaxy formation, and the puzzle of “What seeds supermassive black holes, and how do they grow?” was one of the key questions identified by the Astro2020 Decadal report. Furthermore, the James Webb Space Telescope has identified a surprisingly large number of accreting SMBH at very early times in the universe, challenging our current understanding of black hole formation and growth. However, most current cosmological galaxy formation simulations incorporate crude sub-grid recipes for black hole seeding, growth and feedback. In this project, we plan to study physical mechanisms for black hole seeding using ultra high-resolution simulations. In addition, we will use zoom-in and hyper-refinement techniques to connect galaxy/ cosmological scales with accretion disk scales. In this way, we will inform the outer boundary conditions for “small scale” (hundreds to thousands of gravitational radii) simulations that include general relativity, radiation and magneto-hydrodynamics (GRMHD), in collaboration with the CCA Stars & Plasma Astrophysics (SPA) group. These simulations will then provide the missing physics-based insights into how mass, magnetic fields and angular momentum are transported around black holes across a vast range of scales. These insights will be used to develop new sub-grid treatments of black hole seeding, accretion and feedback that will be implemented into a new CCA-led generation of cosmological simulations.

We’re creating a novel interface between theory and observations to decipher fundamental processes in galaxy formation.

The baryon cycle refers to the cycling of mass, energy and metals through galactic ecosystems. Over the past decade, it has become a central frontier in the field of galaxy formation. We plan to form a new theoretical-observational consortium that will tackle the challenges of understanding the baryon cycle through a novel synergistic approach bringing together researchers working on multi-scale simulations, synthetic observations and multi-tracer, multi-wavelength observations of inflows and outflows from ISM to circumgalactic medium (CGM) to intergalactic medium (IGM) scales.