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We present a family of self-consistent axisymmetric stellar systems that have analytic distribution functions (DFs) of the form f(J), so they depend on three integrals of motion and have triaxial velocity ellipsoids. The models, which are…

Astrophysics of Galaxies · Physics 2015-06-18 James Binney

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

Dark matter (DM) halos formed in CDM cosmologies seem to be characterized by a power law phase-space density profile. The density of the DM halos is often fitted by the NFW profile but a better fit is provided by the Sersic fitting formula.…

Astrophysics · Physics 2009-11-13 Amir Zait , Yehuda Hoffman , Isaac Shlosman

We investigate the physical and observational features of static, spherically symmetric black hole spacetimes surrounded by anisotropic fluid and embedded in a plasma environment. Motivated by recent advances in black hole imaging and…

General Relativity and Quantum Cosmology · Physics 2025-12-15 Jonibek Khasanov , Mirzabek Alloqulov , Pankaj Sheoran , Sanjar Shaymatov , Hemwati Nandan

We have investigated the stability of a set of non-rotating anisotropic spherical models with a phase-space distribution function of the Osipkov-Merritt type. The velocity distribution in these models is isotropic near the center and…

Astrophysics · Physics 2009-10-30 Andres Meza , Nelson Zamorano

We present a new family of spherically symmetric models for the luminous components of elliptical and spiral galaxies and their dark matter haloes. Our starting point is a general expression for the logarithmic slope $\alpha(r) =…

Astrophysics · Physics 2009-11-10 V. F. Cardone , E. Piedipalumbo , C. Tortora

We present a method for fitting orbit-superposition models to the kinematics of discrete stellar systems when the available stellar sample has been filtered by a known selection function. The fitting method can be applied to any model in…

Astrophysics of Galaxies · Physics 2019-01-23 John Magorrian

We present new analytical distribution functions for anisotropic spherical galaxies. They have the density profiles of the gamma-models, which allow a wide range of central density slopes, and are widely used to fit elliptical galaxies and…

Astrophysics · Physics 2008-11-26 Pieter Buyle , Chris Hunter , Herwig Dejonghe

Here we present a kinematic study of the Galactic halo out to a radius of $\sim$ 60 kpc, using 4664 blue horizontal branch (BHB) stars selected from the SDSS/SEGUE survey, to determine key dynamical properties. Using a maximum likelihood…

Astrophysics of Galaxies · Physics 2012-12-04 Prajwal R. Kafle , Sanjib Sharma , Geraint F. Lewis , Joss Bland-Hawthorn

We extract the shape of the stellar velocity ellipsoid as a function of radius in M87 from van der Marel's (1994) velocity dispersion data. We include the gravitational force of a central black hole with the mass quoted by Harms et al.…

Astrophysics · Physics 2009-10-28 David Merritt , Siang Peng Oh

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

Context: The Einasto model has become one of the most popular models for describing the density profile of dark matter haloes. There have been relatively few comprehensive studies on the dynamical structure of the Einasto model, mainly…

Astrophysics of Galaxies · Physics 2022-11-09 Maarten Baes

We construct a new family of models of our Galaxy in which dark matter and disc stars are both represented by distribution functions that are analytic functions of the action integrals of motion. The potential that is self-consistently…

Astrophysics of Galaxies · Physics 2016-12-14 David R. Cole , James Binney

This is an addendum to the paper by Cappellari (2008, MNRAS, 390, 71), which presented a simple and efficient method to model the stellar kinematics of axisymmetric stellar systems. The technique reproduces well the integral-field…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-30 Michele Cappellari

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

The kinematics of stars and planetary nebulae in early type galaxies provide vital clues to the enigmatic physics of their dark matter halos. We fit published data for fourteen such galaxies using a spherical, self-gravitating model with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Curtis J. Saxton , Ignacio Ferreras

We study the kinematics of satellites around isolated galaxies selected from the Sloan Digital Sky Survey (SDSS) spectroscopic catalog. Using a model of the phase-space density previously measured for the halos of LCDM dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-07 Radoslaw Wojtak , Gary A. Mamon

The Jeans equations give the second moments or stresses required to support a stellar population against the gravity field. A general solution of the Jeans equations for arbitrary axisymmetric scale-free densities in flattened scale-free…

Astrophysics · Physics 2015-06-24 N. W. Evans , R. M. Häfner , P. T. de Zeeuw

In the past two decades, it has been established by high-resolution observations of early-type galaxies that their nuclear surface brightness and corresponding stellar mass densities are characterized by cusps. In this paper, we present a…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-22 T. Rindler-Daller

We measure the central kinematics for the dwarf spheroidal galaxy Leo I using integrated-light measurements and previously published data. We find a steady rise in the velocity dispersion from $300^{\prime\prime}$ into the center. The…

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