One of the foremost problems of modern cosmology is the discrepancy between the predicted and observed baryon density, termed the "missing baryon problem". Recent developments in knowledge of cosmological large-scale structure have identified filaments, containing gas belonging the warm-hot intergalactic medium (WHIM), as a potential reservoir for the missing baryons. This phase is often not directly detectable due to its diffuse nature, however detections by means of inverse Comptonization due to the thermal Sunyaev-Zel'dovich effect on CMB photons have been performed. In this thesis, the EAGLE suite of cosmological simulations is used to perform an analysis of filament material joining neighbouring central galaxies. A stacking process to overcome low signal from individual pairs is laid out, and the Comptonization signal y from the averaged pair stack is measured, finding a y-excess of y_filament = (1.299 +/- 0.014) x 10^(-9). In comparing this measurement to recent observational results, I conclude that the excess is statistically significant and indicative of a contribution to the baryon density from WHIM filaments, and set out the direction of further research to better establish the nature of this contribution.
|Date of Award||1 Aug 2021|
- The University of Manchester
|Supervisor||Scott Kay (Supervisor) & Michael Brown (Supervisor)|