The Effect of Bulk Viscosity on the accelerating expansion of the Universe

Project Description:

This project investigates viscous cosmology, in which the cosmic fluid carries a bulk-viscosity contribution that lowers its effective pressure and can in turn drive accelerated expansion. We use recent Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (2024) to test this scenario. After outlining the basics of distance cosmology, we examine how bulk viscosity modifies the standard BAO distance ratios: the volume-averaged, transverse, and line-of-sight distances measured relative to the sound horizon at baryon drag. We then compare these predictions with the standard cosmological model. We then fit the viscous model to DESI DR2 data to disentangle the effects of a viscous fluid from those of a perfect fluid.

Research Area:

Astrophysics

Project Level:

Honours

This Project Is Offered At The Following Node(s):

(UCT)(UKZN)(NWU)