Niels Bohr Institutet > Kalender - det sker på NBI > 2010 > Master thesis defense ...

Master thesis defense by Niels-Erik Kofoed

Niels-Erik Kofod will defend his Master's Thesis Monday 25 January 2010 at 13:00 in the DARK lounge.

Title:
Measuring Lyman Continuum Emission from High Redshift Galaxies

Abstract:
The intergalactic medium in our present Universe is highly ionized. We also know
that before the first stars started shining, the Universe was generally very neutral.
Most astronomers are convinced that these first stars started the reionization of
the Universe. However, the first very luminous stars lived very shortly, so at some
time, other sources of ionizing radiation most have taken over. We are convinced
that quasars play an important role in the ionization of the intergalactic medium at
redshift up to z ~ 3. Beyond this redshift, we do not know for certain what sources
dominated the reionization of of the Universe after the first stars had died out. A
strong candidate for producing ionizing photons are star-forming galaxies such as
Lyman Break Galaxies and Lyman-alpha emitters. However, only a few detections of
ionizing Lyman continuum emission from these galaxies have been reported so far.
This means that we are still very far from understanding the role of these star-forming
galaxies in connection to the reionization of the intergalactic medium.
In this master-thesis I will search for Lyman continuum emission from a sample of
18 Lyman-alpha emitters at z ~ 3.2 and try to estimate the escape fraction of ionizing UV photon relative to the number of non-ionizing UV photons.