Splashback radius of nonspherical dark matter halos from cosmic density and velocity fields
Abstract
We investigate the splashback features of darkmatter halos based on cosmic density and velocity fields. Besides the density correlation function binned by the halo orientation angle, which was used in the literature, we introduce, for the first time, the corresponding velocity statistic, alignment momentum correlation function, to take into account the asphericity of halos. Using largevolume, highresolution N body simulations, we measure the alignment statistics of density and velocity. On halo scales, x ∼R_{200 m}∼1 h^{1} Mpc , we detect a sharp steepening in the momentum correlation associated with the physical halo boundary, or the splashback feature, which is found more prominent than in the density correlation. We also find that the splashback radius determined from the density correlation becomes ∼3.5 % smaller than that from the momentum correlation, with their correlation coefficient being 0.605. Moreover, the orientationdependent splashback feature due to halo asphericity is measured when the density profile is determined by darkmatter particles, which can be used as a test of collisional cold dark matter since the halo shape is predicted to be rounder in such a model.
 Publication:

Physical Review D
 Pub Date:
 July 2018
 DOI:
 10.1103/PhysRevD.98.023523
 arXiv:
 arXiv:1807.02669
 Bibcode:
 2018PhRvD..98b3523O
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 8 pages, 4 figures, published in PRD. This paper is a considerably extended version of the section on Splashback radius of arXiv:1706.08860