scholarly journals Structural Evolution of Substructure

2003 ◽  
Vol 208 ◽  
pp. 403-404
Author(s):  
Eric Hayashi ◽  
Julio F. Navarro
Keyword(s):  
Dark Matter ◽  
Gravitational Potential ◽  
Density Profile ◽  
Outer Region ◽  
Structural Evolution ◽  
Dark Matter Halos ◽  
Initial Profile ◽  
Host System ◽  
Elliptical Orbits ◽  
Mass Profiles

The evolution of substructure in dark matter halos is investigated in a series of simulations of N = 105 satellite halos on elliptical orbits in the gravitational potential of a much larger host system. The bound mass of the satellite decreases with each pericentric passage and most of the mass is lost from the outer region of the satellite halo. We parameterize the change in its density profile by modifying the initial profile by a factor proportional to (1 + r-3), which results in reasonable fits to the mass profiles of tidally stripped subhalos.

scholarly journals Density profile asymptotes at the centre of dark matter halos

2003 ◽  
Vol 404 (3) ◽  
pp. 809-814 ◽  
Author(s):  
J. P. Mücket ◽  
M. Hoeft
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Dark Matter Halos

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.

Rotation Curve and Dark Matter Halo profile in Finsler Geometry

2020 ◽  
Author(s):  
Nupur Paul ◽  
Farook Rahaman ◽  
Nasarul Islam ◽  
S.S. De
Keyword(s):  
Dark Matter ◽  
Rotational Velocity ◽  
Finsler Geometry ◽  
Outer Region ◽  
Recent Time ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Profiles ◽  
Galactic Dark Matter ◽  
Specific Equation

Galactic dark matter is an active area of research in recent time. Several researchers proposed several descriptions of radial profiles of dark matter halos by using N-body simulations. Among them, Navarro, Frenk and White (NFW) dark matter profile provides the most accurate description of dark matter halos. It is believed that dark matter is smooth and distributed uniformly throughout space. Using Finslerian geometrical background and a specific equation of state, we propose a new way to estimate the rotational velocity of galaxies based on the NFW dark matter profile. On small scales the first few distances (about 30 kpc) the velocity increases whereas in the outer region of the galaxies, the rotational velocity is found to be more or less constant which supports observed rotational velocities.

scholarly journals DISTRIBUTION FUNCTION OF DARK MATTER WITH CONSTANT ANISOTROPY

2008 ◽  
Vol 17 (08) ◽  
pp. 1283-1294 ◽  
Author(s):  
DING MA ◽  
PING HE
Keyword(s):  
Dark Matter ◽  
Asymptotic Behavior ◽  
Density Profile ◽  
Anisotropy Parameter ◽  
Outer Part ◽  
Distribution Functions ◽  
Dark Matter Halos ◽  
Spherical Models ◽  
Two Parameters ◽  
Inner Parts

N-body simulations of dark matter halos show that the density is cusped near the center of the halo. The density profile behaves as r–γ in the inner parts, where γ ≃ 1 for the NFW model and γ ≃ 1.5 for the Moore model, but in the outer parts the two models agree with each other in the asymptotic behavior of the density profile. The simulations also show information about the anisotropy parameter β(r) of the velocity distribution: β ≈ 0 in the inner part and β ≈ 0.5 (radially anisotropic) in the outer part of the halo. We provide some distribution functions F(E, L) with the constant anisotropy parameter β for the two spherical models of dark matter halos: a new generalized NFW model and a generalized Moore model. There are two parameters α and ∊ for those two generalized models to determine the asymptotic behavior of the density profile. In this paper, we concentrate on the situation of β(r) = 1/2 from the viewpoint of the simulation.

scholarly journals New Model of Density Distribution for Fermionic Dark Matter Halos

2018 ◽  
Vol 63 (9) ◽  
pp. 769 ◽  
Author(s):  
A. V. Rudakovskyi ◽  
D. O. Savchenko
Keyword(s):  
Dark Matter ◽  
Density Distribution ◽  
Density Profile ◽  
Initial Phase ◽  
Matter Density ◽  
Dark Matter Halos ◽  
New Model ◽  
Dwarf Spheroidal Galaxies ◽  
The Core ◽  
Dirac Distribution

We formulate a new model of density distribution for halos made of warm dark matter (WDM) particles. The model is described by a single microphysical parameter – the mass (or, equivalently, the maximal value of the initial phase-space density distribution) of dark matter particles. Given the WDM particle mass and the parameters of a dark matter density profile at the halo periphery, this model predicts the inner density profile. In the case of initial Fermi–Dirac distribution, we successfully reproduce cored dark matter profiles from N-body simulations. We calculate also the core radii of warm dark matter halos of dwarf spheroidal galaxies for particle masses mFD = 100, 200, 300, and 400 eV.

scholarly journals The differential energy distribution of the universal density profile of dark halo

2003 ◽  
Vol 208 ◽  
pp. 397-398
Author(s):  
Asao Habe ◽  
Chiaki Hanyu
Keyword(s):  
Dark Matter ◽  
Energy Distribution ◽  
Density Distribution ◽  
Density Profile ◽  
Analytical Formula ◽  
Dark Halo ◽  
Dark Matter Halos ◽  
Physical Reason

We study the differential energy distribution of dark matter halos, carrying out cosmological N-body simulation. From our simulation, we give an analytical formula of the differential energy distribution of dark matter in the halos. Density distribution from the analytical formula is consistent with the Navarro, Frenk, and White (NFW) profile. We find that a parameter in our analytical formula of differential energy distribution is related with the slope of inner cusp of dark halo. We discuss physical reason of form of the analytical formula.

scholarly journals Dark matter density profile and galactic metric in Eddington-inspired Born–Infeld gravity

2014 ◽  
Vol 29 (09) ◽  
pp. 1450049 ◽  
Author(s):  
Tiberiu Harko ◽  
Francisco S. N. Lobo ◽  
M. K. Mak ◽  
Sergey V. Sushkov
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Density Profile ◽  
Galactic Center ◽  
Matter Density ◽  
Dark Matter Halos ◽  
Field Equations ◽  
Metric Tensor ◽  
Dark Matter Density ◽  
Gravitational Field Equations

We consider the density profile of pressureless dark matter in Eddington-inspired Born–Infeld (EiBI) gravity. The gravitational field equations are investigated for a spherically symmetric dark matter galactic halo, by adopting a phenomenological tangential velocity profile for test particles moving in stable circular orbits around the galactic center. The density profile and the mass distribution, as well as the general form of the metric tensor is obtained by numerically integrating the gravitational field equations, and in an approximate analytical form by using the Newtonian limit of the theory. In the weak field limit, the dark matter density distribution is described by the Lane–Emden equation with polytropic index n = 1, and is nonsingular at the galactic center. The parameter κ of the theory is determined so that the theory could provide a realistic description of the dark matter halos. The gravitational properties of the dark matter halos are also briefly discussed in the Newtonian approximation.

scholarly journals Inner Structure of Dark Matter Halos

2004 ◽  
Vol 220 ◽  
pp. 99-100 ◽  
Author(s):  
Toshiyuki Fukushige ◽  
Atsushi Kawai ◽  
Junichiro Makino
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Cold Dark Matter ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Cluster Systems

We investigate the structure of the dark matter halo formed in the cold dark matter scenarios by N-body simulations with parallel treecode on GRAPE cluster systems (Fukushige, Kawai, Makino 2003). We simulated 8 halos with the mass of 4.4 × 1014M⊙ to 1.6 × 1015M⊙ in the SCDM and LCDM model using up to 30 million particles. With the resolution of our simulations, the density profile is reliable down to 0.2 percent of the virial radius. Our results show that the slope of inner cusp within 1 percent virial radius is shallower than −1.5, and the radius where the shallowing starts exhibits run-to-run variation, which means the innermost profile is not universal.

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.

Sign in / Sign up

Export Citation Format

Share Document