Accretion by compact objects (white dwarfs, neutron stars and black holes) is amongst the most efficient energy generation processes in the Universe - substantially more efficient that the nuclear reactions that powers stars. Consequently, many of the brightest classes of astrophyiscal systems are powered by accretion and it is the radiation released by accertion that allows us to study the environments of black holes.
Understanding the physics of accretion is very challenging and relies on our ability to interpret observational data for astronomical sources. Key ingredients of such studies are theoretical calculations that allow us to model the X-ray, ultraviolet and optical spectra and connect them to the properties of gas in the vicinity of the accreting object. For this purpose, our collaboration has developed a Monte Carlo radiative transfer code that can compute synthetic spectra for a variety of different models. However, to date, our calcuations have neglected the polarisation states of light and thus provide only intensity spectra. The goal of this project is to investigate the degree of polarisation predicted by particular models and consider how effectively observations of polarisation would help us understand the geometry and dynamics of the gas in and around the accretion flow.
The main part of the project will involve modifying and using our radiative transfer computer program (“Python”) to compute theoretical spectropolarimetry for models of accreting compact objects. In particular, we will focus on implementing a sophisticated approach to track the polarisation state of light in the code and use this to make predictions for existing models of both white-dwarf and black-hole accretion disc winds. The results will be the first modern quantification of predicted ultraviolet/optical spectropolarimetry for this class of model and will help shape the interpretation of polarimetric data and the development of improved models.
This project is theoretical in nature and suitable for students with a background in Physics, Astrophysics and/or Applied Mathematics. Some prior experience of coding, preferrably in the C language, would be advantageous.
The project will involve participating in national and international collaborations, particularly with our team of researchers involved in the development and application of Monte Carlo radiation transfer simulations for accretion disk winds (Southampton and Oxford in the UK; Baltimore and Las Vegas in the USA).
This project is also suitable for MPhil applications
Further Information: Please contact the project supervisor Dr. Stuart Sim