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Mass-modeling methods are used to infer the gravitational field of stellar systems, from globular clusters to giant elliptical galaxies. While many methods exist, most require assumptions about the form of the underlying distribution…

Astrophysics of Galaxies · Physics 2026-04-17 Andrés Bañares-Hernández , Justin I. Read , Mariana P. Júlio

We test a non-parametric higher-order Jeans analysis method, GravSphere, on 32 simulated dwarf galaxies comparable to classical Local Group dwarfs like Fornax. The galaxies are selected from the APOSTLE suite of cosmological hydrodynamics…

We apply four different mass modelling methods to a suite of publicly available mock data for spherical stellar systems. We focus on the recovery of the density and velocity anisotropy as a function of radius, using either line-of-sight…

Astrophysics of Galaxies · Physics 2020-12-02 J. I. Read , G. A. Mamon , E. Vasiliev , L. L. Watkins , M. G. Walker , J. Penarrubia , M. Wilkinson , W. Dehnen , P. Das

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

The Jeans analysis is often used to infer the total density of a system by relating the velocity moments of an observable tracer population to the underlying gravitational potential. This technique has recently been applied in the search…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-21 Thomas Richardson , Malcolm Fairbairn

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

We use a new non-parametric gravitational modelling tool -- \Glass{} -- to determine what quality of data (strong lensing, stellar kinematics, and/or stellar masses) are required to measure the circularly averaged mass profile of a lens and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Jonathan P. Coles , Justin I. Read , Prasenjit Saha

The stellar orbital anisotropy parameter ($\beta_{\rm ani}$) is a persistent systematic uncertainty in galaxy-scale strong gravitational lensing (SGL) cosmology. Typically fixed to isotropy or a local prior, it frequently degenerates with…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-20 Jian Hu , Yi Liu , Jian-Ping Hu , Zhongmu Li

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 measure the velocity anisotropy profile $\beta(r)$ of different galaxy cluster member populations by analysing the stacked projected phase space of nine massive ($M_\mathrm{200c}>7\times10^{14}$ M$_\odot$) galaxy clusters at intermediate…

Astrophysics of Galaxies · Physics 2026-04-15 E. Maraboli , A. Biviano , C. Grillo , A. Mercurio , L. Pizzuti , P. Rosati , M. D'Addona

The spherical Jeans equation is widely used to estimate the mass content of a stellar systems with apparent spherical symmetry. However, this method suffers from a degeneracy between the assumed mass density and the kinematic anisotropy…

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

We add to the lore of spherical, stellar-system models a two-parameter family with an anisotropic velocity dispersion, and a central point mass (``black hole''). The ratio of the tangential to radial dispersions, is constant--and…

Astrophysics · Physics 2009-10-28 Mordehai Milgrom

We present an analytic approach to lift the mass-anisotropy degeneracy in clusters of galaxies by utilizing the line-of-sight velocity dispersion of clustered galaxies jointly with weak lensing inferred masses. More specifically, we solve…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-28 Alejo Stark , Christopher J. Miller , Vitali Halenka

We present an innovative approach to the methodology of dynamical modelling, allowing practical reconstruction of the underlying dark matter mass without assuming both the density and anisotropy functions. With this, the mass-anisotropy…

We present a new method for studying tracers in gravitational systems where higher moments of the line-of-sight velocity distribution are introduced via Virial equations rather than the Jeans equations. Unlike the fourth order Jeans…

Astrophysics of Galaxies · Physics 2014-04-25 Thomas Richardson , Malcolm Fairbairn

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 2009-11-13 Steen H. Hansen , Joachim Stadel

Studies of cluster mass and velocity anisotropy profiles are useful tests of dark matter models, and of the assembly history of clusters of galaxies. These studies might be affected by unknown systematics caused by projection effects. We…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Tania Aguirre Tagliaferro , Andrea Biviano , Gabriella De Lucia , Emiliano Munari , Diego Garcia Lambas

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

We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a…

Astrophysics · Physics 2007-05-23 Gary A. Mamon , Ewa L. Lokas , Teresa Sanchis

We construct a gravitationally decoupled anisotropic strange star model using the minimal geometric deformation approach with a MIT bag equation of state and an additional source sector controlled by a deformation parameter $\beta$ and a…

General Relativity and Quantum Cosmology · Physics 2026-04-17 K. N. Singh , S. K. Maurya , A. Errehymy , A. Altaibayeva , J. Rayimbaev , M. Matyoqubov
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