Power-laws and Non-Power-laws in Dark Matter Halos

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dc.creatorHenriksen, R. N.
dc.date2006-06-27
dc.date2006-09-05
dc.date.accessioned2026-07-07T10:39:24Z
dc.date.available2026-07-07T10:39:24Z
dc.descriptionSimulated dark matter profiles are often modelled as a `NFW' density profile rather than a single power law. Recently, attention has turned to the rather rigorous power-law behaviour exhibited by the `pseudo phase-space density' of the dark matter halo, which is defined dimensionally in terms of the local density and velocity dispersion of the dark matter particles. The non-power-law behaviour of the density profile is generally taken to exclude simple scale-free, in-fall models; however the power-law behaviour of the `pseudo-density' is a counter indication. We argue in this paper that both behaviours may be at least qualitatively understood in terms of a dynamically evolving self-similarity, rather than the form for self-similar infall that is fixed by cosmological initial conditions. The evolution is likely due to collective relaxation such as that provided by the radial-orbit instability on large scales. We deduce, from a distribution function given by first order coarse-graining, both the NFW-type density profile and the power-law pseudo-density profile. The results are not greatly sensitive to variation about 3 in the power of the velocity dispersion used in the definition of the phase space pseudo-density. We suggest that the power 2 may create the more physical quantity, whose deviations from a power-law are a diagnostic of incomplete relaxation.
dc.description31 pages, 4 figures
dc.identifierhttps://arxiv.org/abs/astro-ph/0606654
dc.identifierhttp://arxiv.org/abs/astro-ph/0606654
dc.identifierAstrophys.J.653:894-904,2006
dc.identifierdoi:10.1086/508802
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/181019
dc.subjectAstrophysics
dc.titlePower-laws and Non-Power-laws in Dark Matter Halos
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