Stellar Feedback in Giant Molecular Clouds and Dwarf Galaxies
thesisposted on 13.02.2019, 15:36 authored by Lilian J. Garratt-Smithson
The primary aim of this thesis is to investigate the interplay between time resolved ’gradual’ feedback processes, such as line-driven stellar winds and HMXBs (High Mass X-ray Binaries), with ’instantaneous’ SNe (supernovae). I do this through high resolution SPH (smoothed particle hydrodynamical) simulations of isolated GMCs (Giant Molecular Clouds) and dSphs (Dwarf Spheroidal Galaxies). These systems are of particular interest since their shallow potential wells mean they are susceptible to stellar feedback processes. By modelling HMXBs and SNe in GMCs across a range of parameters, I find that SNe feedback can carve low density chimneys in the gas, offering a path of least resistance for the energy to escape. Once this occurs the more stable, but less energetic, gradual feedback is able to keep the chimneys open. By funneling the hot destructive gas away from the centre of the cloud, chimneys can have a positive effect on both the efficiency and duration of star formation. Furthermore, I included both stellar winds and HMXB feedback on top of SNe in high redshift dwarf galaxies, finding the mass of gas unbound by stellar feedback across a 1 Gyr starburst is uniformly lowered if gradual feedback mechanisms are included, independent of metallicity, galaxy mass, halo concentration and the duration of the starburst. Furthermore, I find including gradual feedback in the smallest galaxies (of halo mass ~10^7 M) delays the unbinding of the gas and facilitates the production of chimneys in the dense shell surrounding feedback-generated hot, pressurised ’superbubbles’. These chimneys vent hot gas from the galaxy interior, lowering the temperature of the central 10 kpc of the gaseous halo. Intriguingly, the underlying dark matter halo of the smallest galaxy is less effected by the gaseous outflows generated by the stellar feedback than the larger halo.