Halo shapes, initial shear field, and cosmic web

7th International Conference on Gravitation and Cosmology

Rossi, G.^1,2,3

School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-Gu, Seoul 130-722, Korea, Republic of^1

CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France^2

Paris Center for Cosmological Physics (PCCP) and Laboratoire APC, Université Paris 7, 75205 Paris, France^3

关键词: Dark matter halos;    Gaussian random fields;    High-resolution numerical simulation;    Initial conditions;    Large scale structures;    Nonlinear evolutions;    Random location;    Theoretical framework;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/484/1/012049/pdf
DOI  :  10.1088/1742-6596/484/1/012049

来源: IOP

【 摘 要 】

The ellipsoidal collapse model, combined with the excursion set theory, allows one to estimate the shapes of dark matter halos as seen in high-resolution numerical simulations. The same theoretical framework predicts a quasi-universal behaviour for the conditional axis ratio distributions at later times, set by initial conditions and unaltered by non-linear evolution. The formalism for halo shapes is also useful in making the connection with the initial shear field of the cosmic web, which plays a crucial role in the formation of large-scale structures. The author has briefly discussed the basic aspects of the modelling, as well as the implications of a new formula for the constrained eigenvalues of the initial shear field, given the fact that positions are peaks or dips in the corresponding density field-and not random locations. This formula leads to a new generalized excursion set algorithm for peaks in Gaussian random fields. The results highlighted, here, are relevant for a number of applications, especially for weak lensing studies and for devising algorithms to find and classify structures in the cosmic web.