On the nature of the primordial Universe, detecting the first generation of stars and galaxies.

  • Date: –16:00
  • Location: Online: Zoom
  • Lecturer: Anton Vikaeus
  • Organiser: Institutionen för fysik och astronomi, avdelningen för fysik och astronomi
  • Contact person: Anton Vikaeus
  • Licentiatseminarium

Contemporary cosmology provides remarkably accurate predictions on the formation of structure in the Universe. The initial fluctuations originating from the inflationary epoch are evolved into the large-scale structure of the Universe, providing us with the present day matter power spectrum. The abundance of dark matter halos collapsing and virializing at high redshift provide estimates on the number density of the formation sites of the first stars in the Universe - the so-called Population III stars. The success of the Lambda-CDM model has granted us insights into the primordial chemical composition of pristine gas and most importantly, its very specific cooling properties as described by quantum mechanics. This has enabled us to pin down the formation sites of the first stars and galaxies to those of dark matter minihalos and atomic cooling halos respectively. As the first stars form in minihalos where baryons cool radiatively via molecular hydrogen around z~30, star formation is suppressed in other surrounding minihalos via radiative feedback dissociating their H2. This suppression enables halos to remain pristine until reaching the atomic cooling threshold whereupon pristine Pop III galaxies may form around z~15. In this thesis we review some of the important physics required in order to understand how the Universe progresses from the early seeds of structure shortly after the big bang into the first luminous - metal-free - objects that we hope to detect in the near future with the arrival of nascent instruments like e.g., the James Webb Space Telescope.