scholarly journals The Phase Space Structure of Dark Matter Halos

2020 ◽  
Author(s):  
Han Aung ◽  
Daisuke Nagai ◽  
Eduardo Rozo ◽  
Rafael García
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Density Profile ◽  
Outer Boundary ◽  
Space Structure ◽  
Space Distribution ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Sharp Drop ◽  
Phase Space Structure

Abstract 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 a sharp drop in the density profile. Using N-body simulations, we model the distribution of the kinematically distinct infalling and orbiting populations of subhalos and halos. We show that the two are mixed spatially all the way to redge, which extends past the splashback radius defined by the drop in the spherically averaged density profile. This edge radius can be interpreted as a radius which contains a fixed fraction of the apocenters of dark matter particles. Our results highlight the possibility of measuring the outer boundary of a dark matter halo using its phase space structure and provide a firm theoretical foundation to the satellite galaxy model adopted in the companion paper (Tomooka et al. 2020), where we analyzed the phase space distribution of SDSS redMaPPer clusters.

scholarly journals New Tools for Probing the Phase Space Structure of Dark Matter Halos

2010 ◽  
Author(s):  
Monica Valluri ◽  
Victor P. Debattista ◽  
Thomas Quinn ◽  
Ben Moore ◽  
Victor P. Debattista ◽  
...  
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Space Structure ◽  
Dark Matter Halos ◽  
Phase Space Structure

scholarly journals Phase-space structure of cold dark matter halos

1992 ◽  
Vol 291 (3) ◽  
pp. 288-292 ◽  
Author(s):  
P. Sikivie ◽  
James R. Ipser
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Cold Dark Matter ◽  
Space Structure ◽  
Dark Matter Halos ◽  
Phase Space Structure

The Role of the Radial Orbit Instability in Dark Matter Halo Formation and Structure

2006 ◽  
Vol 2 (S235) ◽  
pp. 124-124
Author(s):  
J. M. Meyer ◽  
J. J. Dalcanton ◽  
T. R. Quinn ◽  
L. L. R. Williams ◽  
E. I. Barnes ◽  
...  
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Orbit ◽  
Profile Changes ◽  
Analytic Models ◽  
The Universe ◽  
Scale Length

AbstractFor nearly a decade, N-body simulations have revealed a nearly universal dark matter density profile. This density profile appears to be robust to changes in the overall density of the universe and the underlying power spectrum. Despite its universality, however, the physical origin of this profile has not yet been well understood. Semi-analytic models have suggested that scale lengths in dark matter halos may be determined by the onset of the radial orbit instability. We have tested this theory using N-body simulations of collapsing dark matter halos. The resulting halo structures are prolate in shape, due to the mild aspect of the instability. We find that the radial orbit instability sets a scale length at which the velocity dispersion changes rapidly from isotropic to radially anisotropic. Preliminary analysis suggests that this scale length is proportional to the radius at which the density profile changes shape, as is the case in the semi-analytic models; however, the coefficient of proportionality is different by a factor of ~2. We conclude that the radial orbit instability may be a key physical mechanism responsible for the nearly universal profiles of simulated dark matter halos.

scholarly journals The phase-space structure of nearby dark matter as constrained by the SDSS

2017 ◽  
Vol 2017 (06) ◽  
pp. 049-049 ◽  
Author(s):  
Florent Leclercq ◽  
Jens Jasche ◽  
Guilhem Lavaux ◽  
Benjamin Wandelt ◽  
Will Percival
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Space Structure ◽  
Phase Space Structure

scholarly journals DISTRIBUTION FUNCTION IN THE CENTER OF THE DARK MATTER HALO

2009 ◽  
Vol 18 (03) ◽  
pp. 477-484
Author(s):  
DING MA ◽  
PING HE
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Phase Space ◽  
Velocity Dispersion ◽  
Anisotropy Parameter ◽  
Dark Matter Halo ◽  
Phase Space Density ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Space Density

N-body simulations of dark matter halos show that the density profiles of the halos behave as ρ(r) ∝ r-α(r), where the density logarithmic slope α ≃ 1–1.5 in the center and α ≃ 3–4 in the outer parts of the halos. However, some observations are not in agreement with simulations in the very central region of the halos. The simulations also show that the velocity dispersion anisotropy parameter β ≈ 0 in the inner part of the halo and the so-called pseudo–phase-space density ρ/σ3 behaves as a power law in radius r. With these results in mind, we study the distribution function and the pseudo–phase-space density ρ/σ3 of the center of dark matter halos and find that they are closely related.

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