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A simple numerical scheme is presented for the construction of three-integral phase-space distribution functions for oblate galaxy models with a gravitational potential of St\"{a}ckel form, and an arbitrary axisymmetric luminous density…

Astrophysics · Physics 2015-06-24 F. H. A. Robijn , P. T. de Zeeuw

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 use numerical simulations to study a formation scenario for dwarf spheroidal galaxies in which their stellar populations are the products of the dissolution of open star clusters and stellar associations within cosmological dark matter…

Astrophysics of Galaxies · Physics 2015-06-15 Paulina Assmann , Michael Fellhauer , Mark I. Wilkinson , Rory Smith

We study systematically stationary solutions to the coupled Vlasov and Poisson equations which have `self-similar' or scaling symmetry in phase space. In particular, we find analytically {\it all} spherically symmetric distribution…

Astrophysics · Physics 2015-06-24 R. N. Henriksen , Lawrence M. Widrow

Considering galaxies as self - gravitating systems of many collisionless particles allows to use methods of statistical mechanics inferring the distribution function of these stellar systems. Actually, the long range nature of the…

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

The presence of spiral structure in isolated galaxies is a problem that has only been partially explained by theoretical models. Because the rate and pattern of star formation in the disk must depend only on mechanisms internal to the disk,…

Astrophysics · Physics 2009-11-06 D. Cartin , G. Khanna

A method is presented for finding anisotropic distribution functions for stellar systems with known, spherically symmetric, densities, which depends only on the two classical integrals of the energy and the magnitude of the angular…

Astrophysics · Physics 2008-12-31 Zhenglu Jiang , Leonid Ossipkov

We use dynamical models that include bulk rotation, velocity dispersion anisotropy and both stars and dark matter to explore the conditions that give rise to the early-type galaxy scaling relations referred to as the Fundamental Plane (FP)…

Astrophysics of Galaxies · Physics 2015-11-18 Huanian Zhang , Dennis Zaritsky

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

There is good evidence from N-body simulations that the velocity distribution in the outer parts of halos is radially anisotropic, with the kinetic energy in the radial direction roughly equal to the sum of that in the two tangential…

Astrophysics · Physics 2007-05-23 N. W. Evans , J. An

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

We study the dynamical properties of spherical galaxies with surface luminosity profile described by the R^{1/m}-law, in which a variable degree of orbital anisotropy is allowed. The parameter m for the present models covers the range…

Astrophysics · Physics 2007-05-23 L. Ciotti , B. Lanzoni

Modern observational surveys allow us to probe the phase space distribution function (DF) of wide binaries in the Solar neighbourhood. This DF exhibits non-trivial features, in particular a superthermal distribution of eccentricities for…

Astrophysics of Galaxies · Physics 2022-05-04 Chris Hamilton

Starting from an axisymmetric equilibrium distribution function (DF) in action space, representing a Milky Way thin disc stellar population, we use the linearized Boltzmann equation to explicitly compute the response to a three-dimensional…

Astrophysics of Galaxies · Physics 2016-06-23 Giacomo Monari , Benoit Famaey , Arnaud Siebert

The Galactic dwarf spheroidal galaxies (dSphs) provide valuable insight into dark matter (DM) properties and its role in galaxy formation. Their close proximity enables the measurement of line-of-sight velocities for resolved stars, which…

We simultaneously model the gravitational potential and phase space distribution function (DF) of giant stars near the Sun using the {\it Gaia} DR2 radial velocity catalog. We assume that the Galaxy is in equilibrium and is symmetric about…

Astrophysics of Galaxies · Physics 2023-02-01 Haochuan Li , Lawrence Widrow

The dynamical friction timescale of massive globular clusters (GCs) in the inner regions of cuspy dark haloes in dwarf spheroidal (dSph) galaxies can be much shorter than the Hubble time. This implies that a small fraction of the GCs is…

Astrophysics of Galaxies · Physics 2022-02-09 F. J. Sanchez-Salcedo , V. Lora

All dark matter structures appear to follow a set of universalities, such as phase-space density or velocity anisotropy profiles, however, the origin of these universalities remains a mystery. Any equilibrated dark matter structure can be…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Steen H. Hansen , Martin Sparre

The velocity distribution function (VDF) of dark matter (DM) halos in $\Lambda$CDM dissipationless cosmological simulations, which must be non-separable in its radial and tangential components, is still poorly known. We present the first…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-21 Leandro J. Beraldo e Silva , Gary A. Mamon , Manuel Duarte , Radoslaw Wojtak , Sébastien Peirani , Gwenaël Boué

We show different expressions of distribution functions (DFs) which depend only on the two classical integrals of the energy and the magnitude of the angular momentum with respect to the axis of symmetry for stellar systems with known…

Astrophysics · Physics 2009-06-25 Zhenglu Jiang , Leonid Ossipkov