!!!! Bat A, salle de réunion 601 du 6ième étage !!!!
FORMATION OF POWER-LAW CORRELATED STRUCTURES IN COSMOLOGICAL N-BODY SIMULATIONS (I and II)
SYLOS LABINI
Université de Genève & La Sapienza, Roma
Résumé :
In a particle distribution with large-scale small-amplitude
correlations there are
two different sources of fluctuations which can drive gravitational
dynamics.
From one side the intrinsic small-scale fluctuations (which are
inherent to any particle distribution)
having amplitude of order one at the smallest scales in the system
(average distance
between nearest-neighbors $\langle \Lambda_i \rangle$). From the other side
there are, on large scales, some given small-amplitude (i.e. $
\delta \rho / \rho \approx 10^{-3}$)
correlations among density fluctuations. Contrary to the standard
interpretation
based on fluid dynamics, we find that non-linear power-law correlations
in cosmological N-body simulations with small initial velocity dispersion,
which develop around the scale $\langle \Lambda_i \rangle$,
are driven by small-scale particle fluctuations
and not by large-scale smooth fluid-like fluctuations.
Therefore non-linear power-law structure formation does not depend on
the initial large-scale fluctuations: this implies that the
theoretical description should focus on non-analytical
discrete effects in the distribution of matter.
