MSc Thesis Defence - Effect of the Equation of State of Ultra-Dense Matter on the Diffuse Neutrino Background

MSc Candidate

Paul Deguire

Abstract

The equation of state of ultra-dense matter, which gives a relation between microscopic  and macroscopic quantities of ultra-dense objects and describes the core of the most energetic  events of the universe, remains incompletely understood. That is mainly due to the knowledge  gaps of the nuclear force. Different models of the nuclear interaction result in different equations  of state, thus predicting how compressible matter can be, i.e. how soft or stiff nuclear matter is. A  choice of an equation of state is required in hydrodynamic simulations of a binary neutron star  merger, and this choice will influence the evolution of the system. In the first part of this work, I predict the spectrum of neutrinos emitted during a binary neutron star merger by analyzing the results of hydrodynamical simulations. My findings suggest that a soft equation of state produces higher neutrino luminosities than a stiff one for the first few milliseconds of the merger. However, binary neutron star mergers are rare, and neutrinos are hard to detect. Rather than focusing on the neutrinos coming from a single event, I examine the contribution of binary neutron star mergers to the diffuse neutrino background and its detectability in neutrino observatories in the second part of this study. My results predict the detection of the neutrinos relevant to a study of the equation of state to be challenging. Nevertheless, the construction of new generations of gravitational wave detectors and neutrino observatories as well as the development of multi-messenger astronomy make the hunt for those neutrinos promising in a foreseeable future.

Examination Committee

Dr. Eric Poisson, Chair
Dr. Liliana Caballero, Advisor 
Dr. Carl Svensson, Advisory Committee
Dr. Luis Lehner, Advisory Committee