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Solving the puzzle of subhalo spins

Wang, Yang; Lin, Weipeng; Pearce, Frazer R.; Lux, Hanni; Muldrew, Stuart I.; Onions, Julian

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Yang Wang

Weipeng Lin

Frazer R. Pearce

Hanni Lux

Stuart I. Muldrew

Julian Onions


Investigating the spin parameter distribution of subhalos 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 halos. 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 subhalos 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.


Wang, Y., Lin, W., Pearce, F. R., Lux, H., Muldrew, S. I., & Onions, J. (2015). Solving the puzzle of subhalo spins. Astrophysical Journal, 801(2), Article 93.

Journal Article Type Article
Acceptance Date Jan 13, 2015
Publication Date Mar 10, 2015
Deposit Date May 8, 2017
Publicly Available Date May 8, 2017
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 801
Issue 2
Article Number 93
Keywords cosmology: theory, dark matter, galaxies: evolution, galaxies: halos, methods: numerical
Public URL
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