Understanding the Angular Momentum Content of Galaxies in Concert with Their Circumgalactic Medium
Abstract
Legacy observations with HST have enabled fundamental measurements in galaxy formation: the angular momentum of galaxies and the physical state of the circumgalactic medium (CGM). These measurements still require theoretical interpretation in the context of a comprehensive galaxy evolution model. Cosmological hydrodynamical simulations provide this context, and recent ones have reproduced these measurements fairly well, primarily thanks to sub-grid models of strong feedback from star-formation and black holes. In addition to their relation through a common sensitivity to feedback processes, the angular momentum of galaxies and properties of their CGM are also related by direct causality: the internal angular momentum of a galaxy is provided by accretion of angular momentum from its CGM, and is affected by torques exerted by it. Here, we propose to combine these two topics for the first time and interpret these important observational contributions of HST within a unified theoretical framework based on the Illustris simulation suite. These simulations contain large galaxy populations (thousands of L* galaxies), reproduce the main observed features of angular momentum and CGM of L* galaxies, and include a comprehensive model for feedback processes. We will study how feedback prevents the 'angular momentum catastrophe' by performing an in-depth Lagrangian analysis of CGM gas flows, and study the kinematics of the gas in concert with its chemical and ionization state to compare to observations. The analysis of the link between the CGM and angular momentum in simulations will shed light on the formation history of the observed CGM and its ongoing role in galaxy evolution.
- Publication:
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HST Proposal
- Pub Date:
- June 2016
- Bibcode:
- 2016hst..prop14565G