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Solving the Puzzle of Subhalo Spins

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journal contribution
posted on 2015-03-17, 14:53 authored by Y. Wang, W. Lin, F. Pearce, H. Lux, Stuart I. Muldrew, J. 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.


This work was supported by the NSFC projects (grant Nos. 11473053, 11121062, 11233005, U1331201), the National Key Basic Research Program of China (grant No. 2015CB857001), and the “Strategic Priority Research Program the Emergence of Cosmological Structures” of the Chinese Academy of Sciences (grant No. XDB09010000). Y.W. was supported by the EC framework 7 research exchange program LACEGAL. H.L. acknowledges a fellowship from the European Commissions Framework Programme 7, through the Marie Curie Initial Training Network CosmoComp (PITN-GA-2009–238356). S.I. M. acknowledges the support of the STFC Studentship Enhancement Programme (STEP) and the support of a STFC consolidated grant (ST/K001000/1) to the astrophysics group at the University of Leicester. Part of the simulations in this paper were performed on the High Performance Computing (HPC) facilities at the University of Nottingham ( uk/hpc). This work also made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Shanghai Astronomical Observatory.



The Astrophysical Journal: an international review of astronomy and astronomical physics, 2015, 801:93 (10pp)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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