menu

School of Physics and Astronomy

Astronomy Unit menu

Stochastic cosmological lensing Room 516

9 December 2015

Time: 4:30pm
Venue: See Talk Details
Series: The London Relativity and Cosmology Seminar
Speaker: Julien Larena (Rhodes, SA)
Abstract: 

For small cosmological sources like supernovae, the matter distribution along the line of sight cannot accurately be described as a smooth fluid. This questions the applicability of standard cosmological lensing to that type of sources. In this talk, I will present a new method to take into account the granularity of the lensing matter. This method relies on a description of small-scale lensing as a diffusion process; the Sachs and Jacobi equations are recast in the form of Langevin equations for which Fokker-Planck-Kolmogorov equations will be derived. I will then use this formalism to derive some analytical properties of the average and dispersion of the angular diameter distance. Finally, applying the formalism to a particular case of random Swiss-Cheese models, I will present the results of a post Kantowski-Dyer-Roeder approximation, and discuss the shortfalls and future outlooks for the method.

Return to top