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We consider the possibility that dark matter halos are described by the Fermi-Dirac distribution at finite temperature. This is the case if dark matter is a self-gravitating quantum gas made of massive neutrinos at statistical equilibrium.…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-12 Pierre-Henri Chavanis , Mohammed Lemou , Florian Méhats

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

Spherical stellar systems such as King models, in which the distribution function is a decreasing function of energy and depends on no other invariant, are stable in the sense of collisionless dynamics. But Weinberg showed, by a clever…

Astrophysics of Galaxies · Physics 2021-03-03 Douglas C. Heggie , Philip G. Breen , Anna Lisa Varri

We estimate the 3D density profile of the Galactic dark matter (DM) halo within $r \lesssim 30$ kpc from the Galactic centre by using the astrometric data for halo RR Lyrae stars from Gaia DR2. We model both the stellar halo distribution…

Astrophysics of Galaxies · Physics 2021-10-20 Kohei Hattori , Monica Valluri , Eugene Vasiliev

A simple analytical model for describing inner parts of dark matter halo is considered. It is assumed that dark matter density is power-law. The model deals with dark matter distribution function in phase space of adiabatic invariants…

Astrophysics · Physics 2017-04-24 E. Vasiliev

We introduce a very simple model of a dark halo. It is a close relative of Hernquist's model, being generated by the same transformation but this time applied to the logarithmic potential rather than the point mass. The density is…

Astrophysics of Galaxies · Physics 2015-06-22 N. W. Evans , A. A. Williams

We introduce the flattening equation, which relates the shape of the dark halo to the angular velocity dispersions and the density of a tracer population of stars. It assumes spherical alignment of the velocity dispersion tensor, as seen in…

Astrophysics of Galaxies · Physics 2016-05-25 A. Bowden , N. W. Evans , A. A. Williams

We find the distribution function f(E) for dark matter (DM) halos in galaxies and the corresponding equation of state from the (empirical) DM density profiles derived from observations. We solve for DM in galaxies the analogous of the…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-22 H. J. de Vega , N. G. Sanchez

We develop a flexible set of action-based distribution functions (DFs) for stellar haloes. The DFs have five free parameters, controlling the inner and outer density slope, break radius, flattening and anisotropy respectively. The DFs…

Astrophysics of Galaxies · Physics 2015-09-30 A. A. Williams , N. W. Evans

Violent relaxation during the collapse of a galaxy halo is known to be incomplete in realistic cases such as cosmological infall or mergers. We adopt a physical picture of strong but short lived interactions between potential fluctuations…

Astrophysics · Physics 2009-10-31 A. Mangalam , R. Nityananda , S. Sridhar

We present the results of a study of weak lensing by galaxies based on 45.5 deg$^2$ of $R_C$ band imaging data from the Red-Sequence Cluster Survey (RCS). We present the first weak lensing detection of the flattening of galaxy dark matter…

Astrophysics · Physics 2008-11-26 Henk Hoekstra , Howard K. C. Yee , Michael D. Gladders

Model of hard sphere system is important part of modern theories of liquids. Radial distribution function of hard sphere fluid represented in form of explicit analytical expression allows to obtain thermodynamic potentials in analytical…

Statistical Mechanics · Physics 2016-10-11 Timur Aslyamov

The halo mass function, encoding the comoving number density of dark matter halos of a given mass, plays a key role in understanding the formation and evolution of galaxies. As such, it is a key goal of current and future deep optical…

Astrophysics of Galaxies · Physics 2018-03-14 Steven G. Murray , Aaron S. G. Robotham , Chris Power

We develop a simple analytic model for the gravitational clustering of dark matter haloes to understand how their spatial distribution is biased relative to that of the mass. The statistical distribution of dark haloes within the initial…

Astrophysics · Physics 2015-06-24 H. J. Mo , S. D. M. White

We present a new method to construct fully self-consistent equilibrium models of multi-component disc galaxies similar to the Milky Way. We define distribution functions for the stellar disc and dark halo that depend on phase space position…

Astrophysics of Galaxies · Physics 2015-07-03 T. Piffl , Z. Penoyre , J. Binney

Starting from the hypothesis that the Galaxy's dark halo responded adiabatically to the infall of baryons, we have constructed a self-consistent dynamical model of the Galaxy that satisfies a large number of observations, including…

Astrophysics of Galaxies · Physics 2015-10-28 James Binney , Tilmann Piffl

By means of high-resolution N-body simulations we revisited the dissipationless collapse scenario for galaxy formation. We considered both single-component collapses and collapses of a cold stellar distribution in a live dark matter halo.…

Astrophysics · Physics 2009-11-11 C. Nipoti , P. Londrillo , L. Ciotti

We investigate the performance of an analytic model of the 3D matter distribution, which combines perturbation theory with halo models, for weak-lensing statistics. We compare our predictions for the weak-lensing convergence power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-24 Patrick Valageas , Masanori Sato , Takahiro Nishimichi

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

The velocity distribution of dark matter near the Earth is important for an accurate analysis of the signals in terrestrial detectors. This distribution is typically extracted from numerical simulations. Here we address the possibility of…

Astrophysics of Galaxies · Physics 2017-02-08 Andreas Eilersen , Steen H. Hansen , Xingyu Zhang
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