Dark matter subhaloes in numerical simulations |
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| Authors: | Darren Reed Fabio Governato Thomas Quinn Jeffrey Gardner Joachim Stadel George Lake |
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| Institution: | Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE;Astronomy Department, Box 351580, University of Washington, Seattle, WA 98195, USA;INAF, Osservatorio Astronomico di Brera, via Brera 28, I-20131 Milano, Italy;Pittsburgh Supercomputing Centre, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA;Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland;Department of Physics, Washington State University, PO Box 642814, Pullman, WA 99164, USA |
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| Abstract: | We use cosmological Λ cold dark matter (CDM) numerical simulations to model the evolution of the substructure population in 16 dark matter haloes with resolutions of up to seven million particles within the virial radius. The combined substructure circular velocity distribution function (VDF) for hosts of 1011 to 1014 M⊙ at redshifts from zero to two or higher has a self-similar shape, is independent of host halo mass and redshift, and follows the relation d n /d v = (1/8)( v cmax/ v cmax,host)?4 . Halo to halo variance in the VDF is a factor of roughly 2 to 4. At high redshifts, we find preliminary evidence for fewer large substructure haloes (subhaloes). Specific angular momenta are significantly lower for subhaloes nearer the host halo centre where tidal stripping is more effective. The radial distribution of subhaloes is marginally consistent with the mass profile for r ? 0.3 r vir , where the possibility of artificial numerical disruption of subhaloes can be most reliably excluded by our convergence study, although a subhalo distribution that is shallower than the mass profile is favoured. Subhalo masses but not circular velocities decrease towards the host centre. Subhalo velocity dispersions hint at a positive velocity bias at small radii. There is a weak bias towards more circular orbits at lower redshift, especially at small radii. We additionally model a cluster in several power-law cosmologies of P ∝ kn , and demonstrate that a steeper spectral index, n , results in significantly less substructure. |
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| Keywords: | methods: N-body simulations galaxies: formation galaxies: haloes cosmology: theory dark matter |
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