Last updated: December 2022
Neutron stars (NSs) contain the densest form of matter in the observable Universe. For this reason, their bulk properties are powerful probes of both fundamental physics and astrophysics. For instance, their masses depend sensitively on the nature of nuclear interactions, the properties of strong gravity, the late evolution of massive stars, and the supernova (SN) explosion mechanism.
The aim of my PhD research is to obtain novel insights into the NS mass distribution through theoretical modeling and multi-messenger observations. More specifically, my work focuses on the formation, evolution, and properties of NSs formed in electron-capture supernovae (ECSN). The latter are produced when intermediate-mass stars with degenerate oxygen-neon cores explode. Due to the properties of the explosion, ECSN are thought to produce low-mass, low-velocity NSs, which are crucial for explaining the formation of gravitational-wave sources, such as those recently seen by Advanced LIGO and Virgo.
Currently I study the evolution and fates of ECSN progenitor stars in binary systems using state-of-the-art computational tools (MESA). I seek to shed light on the thus-far illusive stellar mass limits that separate white dwarfs, thermonuclear explosions, and NSs. I also investigate how sensitive these transition masses are to input physics uncertainties, for instance, composition, convective overshooting, mass-loss rate, and binary interactions. My work has already resulted in significant breakthroughs: I have identified a novel and seemingly universal mechanism that makes oxygen-neon (ONe) cores to disrupt in thermonuclear explosions instead of producing ECSN (see here). This mechanism may result in a significant paradigm shift, as it produces explosions that are observationally similar to Type Ia supernovae (SNe-Ia), and it suppresses NS formation.
For the remainder of my PhD, I wish to explore the ramifications of my work for the formation of NSs in binary systems, using state-of-the-art models and population synthesis tools. I also plan to put my theories to the test by performing precision mass and velocity measurements of binary pulsars with very long orbital periods. For this latter part I plan to perform pulsar-timing observations with the Large European Array for Pulsars (LEAP) and combine them with data of the European Pulsar Timing Array (EPTA), obtained over the last 20 years. As a member of the EPTA I also wish to contribute towards discovery of low-frequency (nHz) gravitational waves from super-massive binary black holes.