We investigate the three-point functions of the weak lensing cosmic shear, using both analytic methods and numerical results from N-body simulations. The analytic model, an isolated dark matter halo ...with a power-law profile chosen to fit the effective index at the scale probed, can be used to understand the basic properties of the eight three-point functions observed in simulations. We use this model to construct a single three-point function estimator that “optimally” combines the eight three-point functions. This new estimator is an alternative to Map statistics and provides up to a factor of two improvement in signal to noise compared to previously used combinations of cosmic shear three-point functions.
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: A new approach to gravitational instability in large‐scale structure is described, where the equations of motion are written and solved as in field theory in terms of Feynman diagrams. The basic ...objects of interest are the propagator (which propagates solutions forward in time), the vertex (which describes nonlinear interactions between waves) and a source with prescribed statistics which describes the effect of initial conditions. We show that loop corrections renormalize these quantities, and discuss applications of this formalism to a better understanding of gravitational instability and to improving nonlinear perturbation theory in the transition to the nonlinear regime. We also consider the role of vorticity creation due to shell‐crossing and show using N‐body simulations for which at small (virialized) scales the velocity field reaches equipartition, that is, the vorticity power spectrum is about twice the divergence power spectrum.
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On the streaming motions of haloes and galaxies Sheth, Ravi K.; Diaferio, Antonaldo; Hui, Lam ...
Monthly Notices of the Royal Astronomical Society,
09/2001, Volume:
326, Issue:
2
Journal Article
Peer reviewed
Open access
A simple model is described of how objects of different masses stream towards each other as they cluster gravitationally. The model shows how the mean streaming velocity of dark matter particles is ...related to the motions of the parent dark matter haloes. It also provides a reasonably accurate description of how the pairwise velocity dispersion of dark matter particles differs from that of the parent haloes. The analysis is then extended to describe the streaming motions of galaxies. This shows explicitly that the streaming motions measured in a given galaxy sample depend on how the sample was selected, and shows how to account for this dependence on sample selection. In addition, we show that the pairwise dispersion should also depend on sample type. Our model predicts that, on small scales, redshift-space distortions should affect red galaxies more strongly than blue.
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