Resolving shock heating, turbulence and baryon cycle in high redshift massive galaxies
Lead Research Organisation:
University of Cambridge
Department Name: Institute of Astronomy
Abstract
Within the standard picture of galaxy formation developed in the 1970s and 80s, during the structure formation process gas becomes virialised within massive dark matter haloes. Here it attains a high temperature and has a very long cooling time. This has since been questioned by cosmological galaxy formation simulations which find that potentially copious amounts of gas do not shock heat and virialise, but instead deliver cold gas from the cosmic web directly onto galaxies. This significantly changes the way galaxies are built up, leading to much higher central mass deposition rates and hence requiring strong feedback from supernovae and supermassive black holes to prevent excessive star formation rates. These simulations typically lack the required resolution to resolve structure accretion shocks reliably, leading to so-called `in-shock cooling'.
During my PhD, I aim to develop novel computational methods within the moving mesh code AREPO to accurately resolve accretion shocks on-the-fly with unprecedented resolution. This will allow me to run full cosmological simulations of high redshift massive galaxy assembly free from 'in-shock cooling' and to reliably ascertain how gas is cooled and heated as it streams from cosmic filaments onto the galaxies located at the intersection of these filaments. Furthermore, very high resolution at accretion shocks will allow me to capture robustly the generation of vorticity in the wake of curved shocks to estimate how much of the gas energy budget is stored in turbulent motions. The predictions of this work will be directly relevant for future observations by JWST and SKA. My method can be further generalized to increase the spatial resolution within the circumgalactic medium of galaxies, hence allowing not only cosmic inflow but also galaxy outflow multi-phase structure and clumpiness to be captured accurately. This can then be compared against future ALMA and MUSE observations.
During my PhD, I aim to develop novel computational methods within the moving mesh code AREPO to accurately resolve accretion shocks on-the-fly with unprecedented resolution. This will allow me to run full cosmological simulations of high redshift massive galaxy assembly free from 'in-shock cooling' and to reliably ascertain how gas is cooled and heated as it streams from cosmic filaments onto the galaxies located at the intersection of these filaments. Furthermore, very high resolution at accretion shocks will allow me to capture robustly the generation of vorticity in the wake of curved shocks to estimate how much of the gas energy budget is stored in turbulent motions. The predictions of this work will be directly relevant for future observations by JWST and SKA. My method can be further generalized to increase the spatial resolution within the circumgalactic medium of galaxies, hence allowing not only cosmic inflow but also galaxy outflow multi-phase structure and clumpiness to be captured accurately. This can then be compared against future ALMA and MUSE observations.