Speaker: Stefan Arridge, Department of Theoretical Physics
Shining a light on the cosmic web: How quasar absorption lines shape our understanding of the universe
Abstract: In the century following the discovery of the expansion of the universe in the 1920s, the development of our understanding of the physical nature of the universe has reached a point where cosmology is a precision science, with 'Lambda-CDM' as the concordance model. According to this model, only 5 per cent of the energy content of the universe is in the form of baryonic or 'ordinary' matter, with 25 per cent being cold dark matter (CDM) and 70 per cent dark energy (Lambda).
One way to test cosmological models is through numerical simulations, and then to compare the simulated universe with observations of the real universe. In particular, I will talk about a cosmological observable known as the 'Lyman-alpha forest', which is a feature seen in the spectra of distant quasars, caused by neutral hydrogen in the intergalactic medium. Since the neutral hydrogen traces fluctuations in the cosmological matter density field, these absorption features provide information about these fluctuations at different scales, which in turn can place constraints on the nature of dark matter or dark energy. However, complications arise due to effects from complex baryonic physics, which can cause variations in statistics of the Lyman-alpha forest while cosmological parameters are fixed. In this talk, I will talk about the EAGLE simulation model, and discuss the results of numerical experiments in which I vary model parameters.
Zoom details below
Topic: TP Seminar
Time: Nov 20, 2020 14:00 Dublin
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