| Description |
Current cosmological data from the cosmic microwave background and the
distribution of structure on large scales strongly suggest that we
live in a Lambda Cold Dark Matter Universe. As more sky surveys come
online, this model will be put to further tests; given the high level
of statistical significance expected, the interpretation of
observations will require significantly more accurate predictions of
structure formation. Large volume, high-resolution, numerical
simulations provide the only way to sufficiently sharpen the precision
of current models of structure formation. I will discuss some of the
largest scale simulations that have been ever undertaken. I will
discuss the science results about a key ingredient in structure
formation models- the notion of the dark matter halo. Halos host
clusters and galaxies and it is their spatial statistics that are
ultimately measured in surveys. In addition, halo abundance underlies
the use of clusters as a cosmology probe while halo profiles are
important for a wide range of questions such as accurate modelling of
the weak lensing shear power spectrum and how galaxies are distributed
within halos. I will discuss recent work on precision calculations of
halo profiles. The halo profiles can be characterized in terms of a
mass and a concentration following the well-known Navarro-Frenk-White
description. I will discuss how the concentration varies as a function
of mass. At high mass, the c(M) relation flattens out; moreover, at
any mass, the variance of the concentration divided by the mean
concentration is roughly 1/3, independent of cosmology and the
dynamical state of the halo. The mean c-M relation, however, varies at
± 30 % level with cosmology. I will discuss how these results
compare against the observations of cluster profiles. I will then
discuss how these large scale simulations are essential to generate
high resolution synthetic sky needed for the current and the upcoming
CMB polarization surveys.
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