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The shear viscosity to the entropy density ratio $\eta/s$ of the anisotropic superfluid has been calculated by means of the gauge/gravity duality in the presence of the {\it dark matter} sector. The {\it dark matter} has been described by…

High Energy Physics - Theory · Physics 2017-07-26 Marek Rogatko , Karol I. Wysokinski

Some new exact solutions of Einstein's field equations in a spatially homogeneous and anisotropic Bianchi type-V space-time with minimally interaction of perfect fluid and dark energy components have been obtained. To prevail the…

General Physics · Physics 2011-10-06 Anirudh Pradhan , H. Amirhashchi

Traditionally, the mass / velocity anisotropy degeneracy (MAD) inherent in the spherical, stationary, non-streaming Jeans equation has been handled by assuming a mass profile and fitting models to the observed kinematical data. Here, the…

Cosmology and Nongalactic Astrophysics · Physics 2010-02-11 Gary A. Mamon , Gwenael Boué

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 study profiles of mass density, velocity dispersion (VD), and their combination using $\sim 2000$ nearly spherical and rotation-free SDSS galaxies. For observational stellar mass density $\rho_{\star}(r)$ we consider a range of dark…

Astrophysics of Galaxies · Physics 2017-01-04 Kyu-Hyun Chae

We report statistical results for dark matter (DM) velocity anisotropy, \beta, from a sample of some 6000 cluster-size halos (at redshift zero) identified in a \Lambda CDM hydrodynamical adaptive mesh refinement simulation performed with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Doron Lemze , Rick Wagner , Yoel Rephaeli , Sharon Sadeh , Michael L. Norman , Rennan Barkana , Tom Broadhurst , Holland Ford , Marc Postman

Dynamical properties of two-component galaxy models whose stellar density distribution is described by a gamma-model while the total density distribution has a pure r^(-2) profile, are presented. The orbital structure of the stellar…

Astrophysics · Physics 2009-11-13 Luca Ciotti , Lucia Morganti , Tim de Zeeuw

General criteria to check the positivity of the distribution function (phase-space consistency) of stellar systems of assigned density and anisotropy profile are useful starting points in Jeans-based modeling. Here we substantially extend…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Luca Ciotti , Lucia Morganti

Data from 58 strong-lensing events surveyed by the Sloan Lens ACS Survey are used to estimate the projected galaxy mass inside their Einstein radii by two independent methods: stellar dynamics and strong gravitational lensing. We perform a…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-02 Antonio C. C. Guimarães , Laerte Sodré

We study the gravitational instability of a general relativistic complex scalar field with a quartic self-interaction in an infinite homogeneous static background. This quantum relativistic Jeans problem provides a simplified framework to…

General Relativity and Quantum Cosmology · Physics 2018-10-24 Abril Suárez , Pierre-Henri Chavanis

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

Aim: We aim to compute the mass and velocity anisotropy profiles of Abell 2142 and, from there, the pseudo phase--space density profile $Q(r)$ and the density slope - velocity anisotropy $\beta - \gamma$ relation, and then to compare them…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-22 Emiliano Munari , Andrea Biviano , Gary Mamon

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

We determine the range of parameter space of Interacting Quintessence Models that best fits the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. We only consider cosmological models with zero spatial…

Astrophysics · Physics 2009-11-10 German Olivares , Fernando Atrio-Barandela , Diego Pavon

We consider a cosmological model in which the two major fluid components of the Universe, dark energy and dark matter, flow with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid,…

General Relativity and Quantum Cosmology · Physics 2013-07-24 Tiberiu Harko , Francisco S. N. Lobo

In this manuscript, we investigate the patterns satisfied by the cosmological anisotropy under the hypothesis of the observers being co-moving with a perfect fluid whose induced space sections are homogeneous with vanishing scalar…

General Relativity and Quantum Cosmology · Physics 2021-03-31 Leandro G. Gomes

We consider structure formation and CMB anisotropies in a closed universe, both with and without a cosmological constant. The CMB angular power spectrum and the matter transfer function are presented, along with a discussion of their…

Astrophysics · Physics 2009-08-18 Martin White , Douglas Scott

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 use a set of high-resolution simulations of scale-free Einstein-de Sitter cosmologies to investigate the logarithmic slope of the phase-space density profile $Q(r) = \rho(r)/\sigma^3(r)$ of dark matter (DM) haloes. The initial conditions…

Astrophysics · Physics 2009-11-13 Steffen R. Knollmann , Alexander Knebe , Yehuda Hoffman

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