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**Session 86 - Cosmology: Theory.**

*Display session, Friday, January 09*

*Exhibit Hall, *

## [86.06] Measuring the Network Structure in Simulations and Observations

*S. F. Shandarin (U. Kansas)*
Redshift surveys reveal the spectacular abundance of structures in the
spatial galaxy distribution. The filamentary and pancake-like superclusters
of galaxies are linked into a huge network spanning through the entire
universe. Measuring such a patterns was a challenge to theorists for many
years.
Using percolation statistics we, for the first time, demonstrate the
universal character of a network pattern in the real space, mass
distributions resulting from nonlinear gravitational instability of initial
Gaussian fluctuations. Percolation analysis of five stages of the nonlinear
evolution of five power law models (P(k) \propto k^n with n=+3, +1, 0, -1,
and -2 in an Ømega =1 universe) reveals that all models show a shift
toward a network topology if seen with high enough resolution. However,
quantitatively, the shift is significantly different in different models:
the smaller the spectral index n the stronger the shift.

We also employ a percolation technique developed for pointwise
distributions to analyze two-dimensional projections of the three northern
and three southern slices in the Las Campanas Redshift Survey.
As a major result we report a measurement of an unambiguous signal,
with high signal-to-noise ratio (at least at a few \sigmas level),
indicating significantly stronger connectivity of the galaxy distribution
which in two dimensions is indicative of a filamentary distribution.
This is in general agreement with the visual impression and typical
for the standard theory of the large-scale structure formation based on
gravitational instability of initially Gaussian density fluctuations.

**Program
listing for Friday**