The Phase Space Structure of Dark Matter Halos. (arXiv:2003.11557v1 [astro-ph.CO])

<a href="http://arxiv.org/find/astro-ph/1/au:+Aung_H/0/1/0/all/0/1">Han Aung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nagai_D/0/1/0/all/0/1">Daisuke Nagai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rozo_E/0/1/0/all/0/1">Eduardo Rozo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_R/0/1/0/all/0/1">Rafael Garcia</a>

The phase space structure of dark matter halos can be used to measure the

mass of the halo, infer mass accretion rates, and probe the effects of modified

gravity. Previous studies showed that the splashback radius can be measured in

position space using the slope of the density profile. Using N-body

simulations, we show that the phase space structure of the dark matter halo

does not end at this splashback radius. Instead, there exists a region where

infalling, splashback, and virialized halos are mixed spatially. We model the

distribution of the three kinematically distinct populations and show that

there exists an “edge radius” beyond which a dark matter halo has no orbiting

substructures. This radius is a fixed multiple of the splashback radius as

defined in previous works, and can be interpreted as a radius which contains a

fixed fraction of the apocenters of dark matter particles. Our results provide

a firm theoretical foundation to the satellite galaxy model adopted in the

companion paper by Tomooka et al., where we analyzed the phase space

distribution of SDSS redMaPPer clusters.

The phase space structure of dark matter halos can be used to measure the

mass of the halo, infer mass accretion rates, and probe the effects of modified

gravity. Previous studies showed that the splashback radius can be measured in

position space using the slope of the density profile. Using N-body

simulations, we show that the phase space structure of the dark matter halo

does not end at this splashback radius. Instead, there exists a region where

infalling, splashback, and virialized halos are mixed spatially. We model the

distribution of the three kinematically distinct populations and show that

there exists an “edge radius” beyond which a dark matter halo has no orbiting

substructures. This radius is a fixed multiple of the splashback radius as

defined in previous works, and can be interpreted as a radius which contains a

fixed fraction of the apocenters of dark matter particles. Our results provide

a firm theoretical foundation to the satellite galaxy model adopted in the

companion paper by Tomooka et al., where we analyzed the phase space

distribution of SDSS redMaPPer clusters.

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