Seminar

Canadian Institute for Theoretical Astrophysics

Monday, 9 September 1996 at 3:10PM

McLennan Labs, Room 408

Probing Large Scale Structure using Percolation and Genus Curves

Dr. Varun Sahni

IUCAA

We study topological properties of large scale structure in a set of scale free N-body simulations using the genus and percolation curves as topological characteristics. Our results show that as gravitational clustering advances the density field shows an increasingly pronounced departure from Gaussianity reflected in the changing shape of the percolation curve and the changing amplitude and shape of the genus curve. Both genus and percolation curves differentiate between the connectedness of overdense and underdense regions if plotted against the density. When plotted against the filling factor the percolation curve retains this property as well. On the other hand, the genus curve shows very little evolution when plotted against the filling factor. Its shape is very sensitive to the spectrum of primordial density fluctuations and may be a useful indicator of the initial spectrum. Thus the genus and percolation curves provide complementary probes of large scale structure topology. The percolation curve turns out to be a remarkably sensitive probe of non-Gaussianity and can be used to discriminate between models of structure formation and the analysis of observational data such as galaxy catalogs and MBR maps. The genus curve shows a pronounced decrease in amplitude caused by phase correlations in the non-linear regime.