Doctoral dissertation on starburst galaxies by Matthew Hayes

False colour composite image of nearby star forming galaxy ESO 338-IG04 obtained with the Hubble Space Telescope. Hydrogen Lyman-alpha emission is shown in blue, far ultraviolet continuum at ∼ 1500 Å in green, and Hydrogen Balmer-alpha in red. Credit: G. Östlin.

On September 19, Matthew Hayes defends his doctoral thesis titled "Lyman-alpha imaging of starburst galaxies in the local universe and beyond".

One of the primary observational signatures of actively star forming galaxies in the distant universe is the Lyman-alpha emission line (Lyα). In recent years, high-redshift Lyα surveys have been used to constrain cosmic star formation history, investigate large scale structure, and examine the neutral hydrogen fraction of the universe. This doctoral thesis is directly concerned with studies of the Lyα emission from star-forming galaxies and the validity of Lyα as a cosmological tool.

The approach is to study a sample of local actively star forming galaxies using data obtained with the Hubble Space Telescope (HST). Sophisticated tools have been developed for the analysis of the images, resulting also in theoretical exploration of Lyα-related observables from galaxies at high redshift. Model simulations are presented, along with a methodology by which to interpret high-redshift survey data. The HST imaging results in the thesis call into question the interpretations of many high-redshift Lyα surveys and therefore some cosmological estimates may be in error by an order of magnitude. For more information, see the Stockholm University's thesis information.

Time: Wednesday, September 19, 13.00
Place: FB53, AlbaNova University Center, Roslagstullsbacken 21