On the kinematic morphology around haloes

• DOI: 10.1093/mnras/stac3500
• Publication Date: 2022-11-29T15:59:50Z
• Authors: Xiaolin Luo; Xiangling Xu; Xin Wang
• Keywords: 0303 health sciences; 03 medical and health sciences; Cosmology and Nongalactic Astrophysics (astro-ph.CO); FOS: Physical sciences; Astrophysics - Cosmology and Nongalactic Astrophysics

ABSTRACT In this paper, we report an interesting kinematic phenomenon around the haloes’ edge related to the ‘splashback’ radius. After the shell-crossing, cosmic flow exhibits various rotational morphologies via stream-mixing. Vorticity is generated in a particular way that coincides with the large-scale structure. Notably, one specific flow morphology, which is spiralling inward and compressing in the third direction, concentrates around haloes. A detailed examination that reveals a sharp change in the logarithmic derivative of its volume fraction coincides with the location of the splashback radius Rsp defined as the outermost caustic structure. Such a feature encodes valuable phase-space information and provides a new perspective on understanding the dynamical evolution of haloes. As a volume-weighted quantity, the profile of flow morphology is purely kinematic. And unlike other related studies, the rotational flow morphologies capture the anisotropic phase structure in the multistream region.