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Using N-body simulations we study the phenomenon of radial orbit instability occurring in dark matter haloes of the size of a dwarf galaxy. We carried out simulations of seven spherical models, with the same standard NFW density profile but…

Astrophysics of Galaxies · Physics 2016-10-21 Grzegorz Gajda , Ewa L. Lokas , Radoslaw Wojtak

We present theoretical calculations for the differential distribution of stellar orbital eccentricity in a galaxy halo, assuming that the stars constitute a spherical, collisionless system in dynamical equilibrium with a dark matter halo.…

Astrophysics of Galaxies · Physics 2015-05-19 Kohei Hattori , Yuzuru Yoshii

Galaxy models comprising several components (including dark matter) that are bound by the self-consistently generated gravitational field are readily constructed from distribution functions (DFs) that are analytic functions of the action…

Astrophysics of Galaxies · Physics 2026-05-20 James Binney

We have developed spherically symmetric dynamical models of dwarf spheroidal galaxies using Schwarzschild's orbit superposition method. This type of modelling yields constraints both on the total mass distribution (e.g. enclosed mass and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Maarten A. Breddels , A. Helmi , R. C. E. van den Bosch , G. van de Ven , G. Battaglia

We construct a fully self-consistent mass model for the lens galaxy J2141 at z=0.14, and use it to improve on previous studies by modelling its gravitational lensing effect, gas rotation curve and stellar kinematics simultaneously. We adopt…

The standard model of cosmology is underpinned by the assumption of the statistical isotropy of the Universe. Observations of the cosmic microwave background, galaxy distributions, and supernovae, among other media, support the assumption…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-24 Ethan Payne , Sharan Banagiri , Paul Lasky , Eric Thrane

We derive the mass model of the Milky Way (MW) using a cored dark matter (DM) halo profile and recent data. The method used consists in fitting a spherically symmetric model of the Galaxy with a Burkert DM halo profile to available data: MW…

Astrophysics of Galaxies · Physics 2015-06-15 Fabrizio Nesti , Paolo Salucci

Using high-resolution non-radiative hydrodynamic simulations of galaxy clusters we obtain simple analytic formulae for DM and gas distribution in the spherical approximation. We derive fits for the DM density, velocity dispersion and…

Astrophysics · Physics 2008-11-26 Elena Rasia , Giuseppe Tormen , Lauro Moscardini

We add black holes to nonrotating, spherical galaxy models, with the assumption that the black-hole growth is slow compared with the dynamical time but fast compared with the relaxation time. The outcome differs depending on whether the…

Astrophysics · Physics 2010-04-29 Gerald D. Quinlan , Lars Hernquist , Steinn Sigurdsson

We use oblate axisymmetric dynamical models including dark halos to determine the orbital structure of intermediate mass to massive Coma early-type galaxies. We find a large variety of orbital compositions. Averaged over all sample galaxies…

One can solve the Jeans equation analytically for equilibrated dark matter structures, once given two pieces of input from numerical simulations. These inputs are 1) a connection between phase-space density and radius, and 2) a connection…

Astrophysics · Physics 2015-06-24 Steen H. Hansen , Ben Moore , Joachim Stadel

Elliptical galaxies are modelled with a a 4-component model: Sersic stars, LCDM dark matter (DM), hot gas and central black hole. DM is negligible in the inner regions, which are dominated by stars and the central black hole. This prevents…

Astrophysics · Physics 2014-12-15 Gary A. Mamon , Ewa L. Lokas

We present a proposal for the full phase space distribution of the Milky Way halo. The model is axially and reflection symmetric and its time evolution is self-similar. It describes the halo as a set of discrete dark matter flows with…

Astrophysics · Physics 2009-02-20 L. D. Duffy , P. Sikivie

In the solution of the Jeans equations for axisymmetric galaxy models the ``$b$-ansatz" is often adopted to prescribe the relation between the vertical and radial components of the velocity dispersion tensor, and close the equations.…

Astrophysics of Galaxies · Physics 2025-11-05 Leonardo De Deo , Luca Ciotti , Silvia Pellegrini

Assuming the separable augmented density, it is always possible to construct a distribution function of a spherical population with any given density and anisotropy. We consider under what conditions the distribution constructed as such is…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-19 J. An , E. Van Hese , M. Baes

A widely employed method for estimating the mass of stellar systems with apparent spherical symmetry is dynamical modelling using the spherically symmetric Jeans equation. Unfortunately this approach suffers from a degeneracy between the…

Astrophysics of Galaxies · Physics 2015-06-19 Foivos I. Diakogiannis , Geraint F. Lewis , Rodrigo A. Ibata

Dwarf spheroidal galaxies (dSphs) are prime laboratories for studying dark matter (DM) and the black hole demographics in the low-mass regime. These systems are also often flattened; nevertheless most studies rely on spherical models,…

Astrophysics of Galaxies · Physics 2026-04-29 R. Pascale , G. Battaglia , J. M. Arroyo-Polonio , E. Vasiliev , C. Nipoti , G. F. Thomas

Dark matter mass density profiles and velocity distributions for a set of dwarf spheroidal galaxies (dSphs) have recently been obtained (F.Bezrukov, D.Gorbunov, E.Koreshkova arXiv:2412.20585) by performing a multi-parametric fit to the…

Astrophysics of Galaxies · Physics 2025-09-12 Fedor Bezrukov , Dmitry Gorbunov , Ekaterina Koreshkova

We study the distribution of dark matter in dwarf spheroidal galaxies by modelling the moments of their line-of-sight velocity distributions. We discuss different dark matter density profiles, both cuspy and possessing flat density cores.…

Astrophysics · Physics 2009-11-07 Ewa L. Lokas

We present density profiles, that are solutions of the spherical Jeans equation, derived under the following two assumptions: (i) the coarse grained phase-density follows a power-law of radius, rho/(sigma^3) proportional to r^{-alpha}, and…

Astrophysics · Physics 2009-11-07 Nicolaos Hiotelis