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We study velocity moments of elliptical galaxies in the Coma cluster using Jeans equations. The dark matter distribution in the cluster is modelled by a generalised formula based upon the results of cosmological N-body simulations. Its…

Astrophysics · Physics 2009-09-29 Ewa L. Lokas , Gary A. Mamon

We consider the problem of determining the structure of the dark halo of nearby dwarf spheroidal galaxies (dSphs) from the spherical Jeans equations. Whether the dark halos are cusped or cored at the centre is an important strategic problem…

Astrophysics · Physics 2009-11-13 N. W. Evans , J. An , M. G. Walker

We introduce a novel implementation of orbit-based (or Schwarzschild) modeling that allows dark matter density profiles to be calculated non-parametrically in nearby galaxies. Our models require no assumptions to be made about velocity…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 John R. Jardel , Karl Gebhardt , Maximilian Fabricius , Niv Drory , Michael J. Williams

We analyze three epochs of HST imaging over 20 years for the Sculptor dwarf spheroidal galaxy, measuring precise proper motions for 119 stars and combining them with 1760 existing line-of-sight velocities. This catalog yields the first…

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

The core-cusp problem is one of the controversial issues in the standard paradigm of $\Lambda$ cold dark matter ($\Lambda$CDM) theory. However, under the assumption of conventional spherical symmetry, the strong degeneracy among model…

Astrophysics of Galaxies · Physics 2020-12-02 Kohei Hayashi , Masashi Chiba , Tomoaki Ishiyama

We investigate the mass distributions within eight classical Milky Way dwarf spheroidal galaxies (MW dSphs) using an equilibrium Jeans analysis and we compare our results to the mass distributions predicted for subhalos in dissipationless…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-21 Joe Wolf , James S. Bullock

Dark matter N-body simulations suggest that the velocity distribution of dark matter is anisotropic. In this work we employ a mass model for the Milky Way whose parameters are determined from a fit to kinematical data. Then we adopt an…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Nassim Bozorgnia , Riccardo Catena , Thomas Schwetz

Distinguishing a core and a cusp within dark matter halos is complexified by the existence of mass-anisotropy degeneracy, where various combinations of velocity anisotropy ($\beta$) and inner density slope ($\gamma$) yield similar…

Astrophysics of Galaxies · Physics 2025-02-21 Dafa Wardana , Masashi Chiba , Kohei Hayashi

Using cosmological N-body simulations we study the radial velocity distribution in dark matter haloes focusing on the lowest-order even moments, dispersion and kurtosis. We determine the properties of ten massive haloes in the simulation…

Astrophysics · Physics 2009-11-10 Radoslaw Wojtak , Ewa L. Lokas , Stefan Gottloeber , Gary A. Mamon

We apply two new state-of-the-art methods that model the distribution of observed tracers in projected phase space to lift the mass / velocity anisotropy (VA) degeneracy and deduce constraints on the mass profiles of galaxies, as well as…

Astrophysics of Galaxies · Physics 2015-10-13 G. A. Mamon , J. Chevalier , A. J. Romanowsky , R. Wojtak

We summarize the method of mass modelling of galaxy clusters based on reproducing the dispersion and kurtosis of the projected velocity distribution of galaxies. The models are parametrized within the framework of the NFW density profile,…

Astrophysics · Physics 2007-12-17 Ewa L. Lokas , Radoslaw Wojtak , Gary A. Mamon , Stefan Gottloeber

We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest…

We show that measuring the proper motion of ${{\sim 2000}}$ stars within a dwarf galaxy, with an uncertainty of 1 km/s at most, can establish whether the Dark Matter (DM) density profile of the dwarf has a central core or cusp. We derive…

Astrophysics of Galaxies · Physics 2022-08-31 Ivan de Martino , Antonaldo Diaferio , Luisa Ostorero

Dwarf galaxies are small, dark matter-dominated galaxies, some of which are embedded within the Milky Way. Their lack of baryonic matter (e.g., stars and gas) makes them perfect test beds for probing the properties of dark matter --…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-22 Tri Nguyen , Siddharth Mishra-Sharma , Reuel Williams , Lina Necib

The distribution of dark matter in the inner regions of galaxies poses a key challenge for small-scale {\Lambda}CDM cosmology. While cold dark matter simulations predict cuspy inner density profiles, observations of low surface brightness…

Astrophysics of Galaxies · Physics 2026-02-09 Sougata Sarkar , Prerana Biswas , Veselina Kalinova , Nirupam Roy , Narendra Nath Patra , Sushma Kurapati

We use high-resolution N-body simulations to follow the formation and evolution of tidal streams associated to dwarf spheroidal galaxies (dSphs). The dSph models are embedded in dark matter (DM) haloes with either a centrally-divergent…

Astrophysics of Galaxies · Physics 2016-02-22 Raphaël Errani , Jorge Peñarrubia , Giuseppe Tormen

Using cosmological N-body simulations we study the line-of-sight velocity distribution of dark matter haloes focusing on the lowest-order even moments, dispersion and kurtosis, and their application to estimate the mass profiles of…

Astrophysics · Physics 2009-11-13 Radoslaw Wojtak , Ewa L. Lokas , Stefan Gottloeber , Gary A. Mamon

We demonstrate the existence of distribution functions that can be used to represent spherical massless cored stellar systems embedded in cuspy dark matter halos with constant mildly tangential velocity anisotropy. In particular, we derive…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Maarten A. Breddels , Amina Helmi

We investigate constraints on the inner stellar density profile from photometric data of dwarf spheroidal and ultra-faint dwarf galaxies. Our aim is to clarify under what conditions cored stellar profiles require dark matter halos that are…