Observing the Unobservable: Catching a Glimpse of the Primordial Universe
Abstract
In this thesis we discuss the primordial Universe and prospects for detection of smoking gun signatures related to the earliest stages of cosmic evolution. In the first part of this thesis we focus on the epoch of formation of the very first stars and galaxies when the Universe was only ∼ 30-200 million years old. We explore the details of primordial structure formation taking into account a complete set of initial conditions, which include fluctuations in density as well as relative velocities between dark matter and baryons at recombination. We discuss observational prospects related to this era using the redshifted 21-cm emission line of neutral hydrogen and explore the dependence of this radio signal on the complex astrophysics of the early epoch as well as on the relative velocities. This research shows that the prospects for detection of the redshifted 21-cm signal related to the early period are much more promising than was previously thought. The results presented here are likely to stimulate observational efforts focused on the epoch of the primordial star formation. In the second part, we consider cosmological signatures related to a modified set of initial conditions from inflation, focusing on a particular scenario of pre-inflationary relics which was originally motivated by string theory. We entertain the possibility that one such a relic may affect initial conditions for structure formation within our observable Universe, and explore its observational consequences. This study explores the interface between high energy theories and cosmic measurements and opens a unique observational window at the high energy scales of ∼ 10^16 - 10^18 GeV.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 2013
- Bibcode:
- 2013PhDT........67F