Core-Collapse Supernova Physics in the Multi-Messenger Era

Citation

Gossan, Sarah Elizabeth (2019) Core-Collapse Supernova Physics in the Multi-Messenger Era. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ZF1A-6394. https://resolver.caltech.edu/CaltechTHESIS:01312019-123521450

Abstract

Eighty-five years following the historic proposal that core-collapse supernovae accompanied the transition of evolved massive stars to neutron stars [1], the mechanism through which these collapsing stars explode remains uncertain. While supernovae are observed on a daily basis across the electromagnetic spectrum, neutrinos and gravitational waves, emitted from the very heart of the core-collapse supernova central engine, provide a direct glimpse of the dynamics driving the explosion. The joint gravitational wave and electromagnetic observations of a colliding neutron star binary system on 17th August 2017 heralded a new era for multi-messenger astronomy [2]. The next galactic core-collapse supernova presents an unparalleled opportunity to directly probe core-collapse supernova physics and the explosion mechanism.

This thesis explores a number of topics in multi-messenger astronomy and core-collapse supernova physics. First, it tackles the observation problem; detailing an astrophysically motivated search protocol for gravitational waves from core-collapse supernovae triggered by observations of neutrino and/or electromagnetic counterparts. Applying these methods to a number of hypothetical observational scenarios, it presents sensitivity estimates for the second generation of gravitational wave interferometric detectors to both realistic and speculative emission mechanisms associated with core-collapse supernovae. Next, it addresses the prospects for post-detection inference; developing a Bayesian toolkit to interpret gravitational wave observations from core-collapse supernovae and augment current understanding of the explosion mechanism. A proof-of-principle study is also presented, using tailor-made simulations to demonstrate the viability of extracting the angular momentum distribution of nascent millisecond proto-neutron stars from their gravitational wave echoes. Thereafter, it considers the ramifications of failure to accurately capture proto-neutron star hydrodynamics in core-collapse supernova simulations; exploring the influence on the explosion mechanism of gravito-acoustic waves generated by convection in the proto-neutron star mantle. Finally, it ponders the impact of advances in multi-messenger astronomy and source modelling over the next twenty years on the understanding of core-collapse supernova physics.

Thesis Files