---
abstract: 'Investigating the spin parameter distribution of sub[haloes]{} in two high resolution isolated halo simulations, recent work by Onions et al. suggested that typical subhalo spins are consistently lower than the spin distribution found for field [haloes]{}. To further examine this puzzle, we have analyzed simulations of a cosmological volume with sufficient resolution to resolve a significant subhalo population. We confirm the result of Onions et al. and show that the typical spin of a subhalo decreases with decreasing mass and increasing proximity to the host halo center. We interpret this as the growing influence of tidal stripping in removing the outer layers, and hence the higher angular momentum particles, of the sub[haloes]{} as they move within the host potential. Investigating the redshift dependence of this effect, we find that the typical subhalo spin is smaller with decreasing redshift. This indicates a temporal evolution as expected in the tidal stripping scenario.'
author:
- 'Yang Wang, Weipeng Lin, Frazer R. Pearce, Hanni Lux, Stuart I. Muldrew & Julian Onions'
bibliography:
- 'mn-jour.bib'
- 'Haloes.bib'
title: '[Solving the puzzle of subhalo spins]{}'
---

Introduction {#sec:introduction}
============

In the standard model of structure formation, the rotation velocities of disc galaxies are correlated 