Skip to main content
Open Access Publications from the University of California

UC San Diego

UC San Diego Electronic Theses and Dissertations bannerUC San Diego

Measurements of Primordial Deuterium and Lyman-Alpha Forest Evolution with High-Resolution Quasar Spectroscopy

  • Author(s): Gustafson, Scott Matthew
  • Advisor(s): Tytler, David
  • et al.

A precise determination of the light-element abundances produced during the epoch of Big Bang Nucleosynthesis (BBN) is an important probe of the early universe. The Deuterium-Hydrogen abundance ratio (D/H) is of particular importance due to its sensitivity to the cosmological baryon density, its use as a constraint of non-standard BBN scenarios and the fact that Deuterium is not created outside of BBN, but destroyed inside of stars at a predictable rate, so any Deuterium observed in interstellar or intergalactic gas is primordial. Due to the difficulty of measurements and relative rarity of appropriate conditions required to observe D in quasar absorption systems, there are only 15 published measurements of the primordial D/H in literature. Here we examine the primordial Deuterium-to-Hydrogen abundance ratio using high-resolution optical spectroscopy of diffuse gas towards two quasars. We measure \DI\ towards the bright Quasar J1201$+$0116 at moderate redshift ($z=2.98$) in a Lyman-Limit system (N=$10^{17.41}\cmm$) which exhibits very low metal content indicating pristine conditions ([Si/H]=$-3.3 \pm 0.8$). This value, $10^5$D/H=$2.50\pm 0.18$ is in complete agreement with D/H from the CMB and theory. We measure \DI\ in one component of DLA towards quasar J0744$+$2059 (N=$10^{20.8} \cmm$) and measure D/H to be $ 2.359 \pm 0.095$ \textemdash $2\sigma$\ lower than D/H from theory and the CMB. Additionally, we present measurements on the \lyaf\ towards 25 high-resolution QSO. The statistics we report are suitable for comparison to simulations, which are the primary means of extracting physical information from the Intergalactic Medium.

Main Content
Current View