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We study the shapes of galaxy dark matter haloes by measuring the anisotropy of the weak gravitational lensing signal around galaxies in the second Red-sequence Cluster Survey (RCS2). We determine the average shear anisotropy within the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Edo van Uitert , Henk Hoekstra , Tim Schrabback , David G. Gilbank , Michael D. Gladders , H. K. C. Yee

We present the results of a study of the average mass profile around galaxies using weak gravitational lensing. We use 45.5 deg^2 of R_C band imaging data from the Red-Sequence Cluster Survey (RCS) and define a sample of 1.2\times 10^5…

Astrophysics · Physics 2007-05-23 Henk Hoekstra , Howard K. C. Yee , Michael D. Gladders

Following a number of conflicting studies of M87's mass profile, we undertake a dynamical analysis of multiple tracer populations to constrain its mass over a large radius range. We combine stellar kinematics in the central regions with the…

Astrophysics of Galaxies · Physics 2016-01-27 L. J. Oldham , M. W. Auger

The anomalous rotation curves of galaxies provide compelling evidence for dark matter, yet its fundamental nature and distribution remain key unresolved issues in astrophysics. In this work, we investigate a dark matter model derived from…

General Relativity and Quantum Cosmology · Physics 2025-09-17 Jan Kuncewicz

According to the now strongly supported concordance $\Lambda$CDM model, galaxies may be grossly described as a luminous component embedded in a dark matter halo. The density profile of these mass dominating haloes may be determined by N -…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-04 A. Del Popolo , V. F. Cardone

The velocity anisotropy of particles inside dark matter (DM) haloes is an important physical quantity, which is required for the accurate modelling of mass profiles of galaxies and clusters of galaxies. It is typically measured using the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Radoslaw Wojtak , Stefan Gottloeber , Anatoly Klypin

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

We use high-quality optical rotation curves of 9 low-luminosity disk galaxies to obtain the velocity profile of the surrounding dark matter halos. We find that they increase linearly with radius at least out to the stellar disk edge,…

Astrophysics · Physics 2009-10-31 A. Borriello , P. Salucci

The model of galactic halo as a system of the collisionless small neutral particles from the standpoint of kinetic theory is considered. For the equilibrium system with the use of Maxwell-Boltzmann distribution we obtained results which…

General Relativity and Quantum Cosmology · Physics 2011-11-03 Valentin D. Gladush

The stellar density profile a galaxy is typically summarised with two numbers: total stellar mass and half-light radius. The total mass of a galaxy, however, is not a well-defined quantity, due to the finite depth of photometric…

Astrophysics of Galaxies · Physics 2020-09-23 Alessandro Sonnenfeld

The spectrum of cold dark matter particles on Earth is expected to have peaks in velocity space associated with particles which are falling onto the Galaxy for the first time and with particles which have fallen in and out of the Galaxy…

Astrophysics · Physics 2010-11-30 P. Sikivie , I. I. Tkachev , Yun Wang

This paper discusses a new model for galactic dark matter by combining an anisotropic pressure field corresponding to normal matter and a quintessence dark energy field having a characteristic parameter $\omega_q$ such that $-1<\omega_q<…

General Relativity and Quantum Cosmology · Physics 2011-07-15 F. Rahaman , Peter K. F. Kuhfittig , K. Chakraborty , M. Kalam , D. Hossain

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 develop a method for recovering the global density distribution of the ancient Galactic stellar halo prior to disk formation, based on the present orbits of metal-poor stars observed in the solar neighborhood. The method relies on the…

Astrophysics · Physics 2009-10-31 Masashi Chiba , Timothy C. Beers

The galactic component in clusters is commonly thought to be generally nonrotating and in a dynamical state different from that of a collisionally relaxed system. In practice, a test of such a picture is often not available. We consider the…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-11 Giovanni Ferrami , Giuseppe Bertin , Claudio Grillo , Amata Mercurio , Piero Rosati

Two distinct non-singular interior models that describe anisotropic spherical configurations are presented in this work. We develop the Einstein field equations and the associated mass function in accordance with a static spherical…

General Relativity and Quantum Cosmology · Physics 2025-10-10 M. Sharif , Tayyab Naseer , Hira Shadab

We present a class of exact solutions of Einstein's gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by assuming a particular form of the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 T. Harko , M. K. Mak

We study the phase-space structure of a dark-matter halo formed in a high resolution simulation of a Lambda CDM cosmology. Our goal is to quantify how much substructure is left over from the inhomogeneous growth of the halo, and how it may…

Astrophysics · Physics 2009-09-25 Amina Helmi , Simon D. M. White , Volker Springel

[Abridged] N-body simulations of collisionless collapse have offered important clues to the construction of realistic stellar dynamical models of elliptical galaxies. Understanding this idealized and relatively simple process, by which…

Astrophysics · Physics 2009-11-10 M. Trenti , G. Bertin , T. S. van Albada

We describe a non-parametric method for determining both the anisotropy and mass profiles of elliptical galaxies from velocity dispersions and velocity profile shapes along the line of sight. In this way, mass-to-light ratios out to 2-3…

Astrophysics · Physics 2007-05-23 Andi Kronawitter , Ortwin E. Gerhard , R. P. Saglia , Ralf Bender