Supernovae are the explosive deaths of stars, occurring at the end of stellar evolution for very massive stars and certain types of binary star system. They are important to a number of modern astrophysical topics: most of the heavy elements are synthesised in supernova explosions, supernovae inject energy and momentum to the interstellar medium and some classes of supernovae can be used as accurate cosmic distance indicators, making it possible to map out the expansion history of the Universe.
The current generation of astronomical surveys (including the PESSTO survey led from Queens) are yielding observational data of unprecedented quantity and quality. Thanks to these, we have uncovered a startling array of new and unexpected phenomena in astronomical explosions: sometimes unexpected properties of previously known classes of transient and in other cases completely new types of event. These new discoveries can test and challenge our theoretical picture and are currently driving a new wave of development and exploration of supernova theory.
Although it is generally accepted that Type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars, the physical mechanism by which these explosions occur is not yet understood and so it remains unclear how these speculator events actually come about. Clues to solving this mystery can be found in the spectra (and light curves / spectropolarimetry) observed and, thanks to modern instrumentation, the quantity and quality of such data is continuously improving.
Interpreting high quality observational data often requires theoretical modelling. The PhD project will focus on performing radiative transfer simulations to compute synthetic spectra and light curves from explosion models and comparing these to real observational data. Although the focus of the project can be tailored to suit the student's interest, a specific aim will be to make, and test, predictions for observable signatures of the SN Ia explosion mechanism. In particular, we will investigate the formation of hydrogen and helium spectral features: since only traces of these elements are expected to be present in the exploding white dwarf, their identification (or non-detection) offer vital clues to the nature of a potentially hydrogen- or helium-rich binary companion star.
The student will learn the physical principles and computational algorithms used in Monte Carlo radiative transfer calculations and will become experienced in running and analysing the results of simulations. Depending on the student's skills/interests, the project will focus on a combination of improving the quality of the simulations and modelling of observations.
The QUB supernova/transient group currently consists of three faculty staff, two senior research fellows, five postdoctoral researchers and four PhD students. The project will involve collaboration within the QUB group and also with international researchers. In particular, we will work close with theorists developing thermonuclear supernova explosion models in Heidelberg, Munich and Stockholm.
Further Information: Please contact the project supervisor Dr. Stuart Sim