Cosmology, Big Bang nucleosynthesis, Cosmological Lithium Problem, galactic chemical evolution

Our deepest understanding of the Universe and its mechanics is captured by a simple, elegant concept - the Standard Model of particle physics and cosmology. One of the prime goals of this PhD project is to test the foundations of this framework. This will be achieved by studying a period of time (a few minutes after the Big Bang) during which the first chemical elements of the periodic table were made.

These are referred to as the 'primordial' elements, and include hydrogen, helium, lithium, and their isotopes. The amount of each primordial element made during this time is sensitive to every known fundamental force: gravity, electromagnetism and the strong and weak nuclear forces. Thus, the relative production of these primordial elements can be used to probe the physics of the Universe just a few minutes after the Big Bang.

To measure the primordial elements, environments must be found that remain as uncontaminated as possible since the Big Bang. For example, the oldest stars in our Galaxy are often used to measure the ratio of primordial lithium to hydrogen (Li/H). At present, such measures disagree significantly with the Standard Model, giving rise to a puzzle known as the `Cosmological Lithium Problem'.

After more than a decade of research, it still remains unclear if the observations need revision, or if this discrepancy requires new (presently unknown) physics beyond the Standard Model.

To solve this impasse, the PhD student assigned to this project will measure the Li/H ratio of gas clouds (instead of stars, as previously done) using data collected with some of the World's largest optical telescopes.