Discipline: 
Physics
Status: 
Available
Level: 
PhD Project
Level: 
Masters Project
Level: 
Honours Project
Level: 
Summer Project
Supervisor(s): 
Dr. Ed Macaulay

Studying the velocities of galaxies is one of the most direct methods we can use to map out the invisible ‘Dark Matter’, which appears to comprise much of the Universe.  Conventionally, this is done in two distinct steps: firstly, observational parameters are fitted to the galaxies to find their distances and velocities.  Once these velocities are found, they are then used to calculate cosmological parameters, such as the average bulk flow of the galaxies, or their large-scale statistical distribution.  These results have posed somewhat of a long-standing challenge to the current cosmological model, often suggesting larger than expected fluctuations at the largest scales of the matter distribution.

However, the conventional two-step process of studying peculiar velocities has several drawbacks, which may be influencing these cosmological results.  This project will focus on developing a one-step process to simultaneously fit for the peculiar velocity and cosmological parameters. The project will involve learning about the different observational methods used to measure peculiar velocities, and Markov Chain Monte Carlo (MCMC) techniques for fitting parameters. We will start with a simplified version of the problem, and work towards the full one-step process, depending on progress.  Ideally, the one-step method should maximise the amount of available information in the catalogues, and help to infer which factors are driving the cosmological results.