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We introduce a new family of random compact metric spaces $\mathcal{S}_\alpha$ for $\alpha\in(1,2)$, which we call stable shredded spheres. They are constructed from excursions of $\alpha$-stable L\'evy processes on $[0,1]$ possessing no…

Probability · Mathematics 2021-05-27 Jakob Björnberg , Nicolas Curien , Sigurdur Örn Stefánsson

Simple analytical models, such as the Hernquist model, are very useful tools to investigate the dynamical structure of galaxies. Unfortunately, most of the analytical distribution functions are either isotropic or of the Osipkov-Merritt…

Astrophysics · Physics 2009-11-07 Maarten Baes , Herwig Dejonghe

The spherical Jeans equation (SJE) is widely used in dynamical modelling of the Milky Way (MW) halo potential. We use haloes and galaxies from the cosmological Millennium-II simulation and hydrodynamical APOSTLE simulations to investigate…

Astrophysics of Galaxies · Physics 2018-03-21 Wenting Wang , Jiaxin Han , Shaun Cole , Surhud More , Carlos Frenk , Matthieu Schaller

We use orbit based dynamical models to fit the 2nd and 4th moments of the line of sight velocity distributions of the Fornax, Sculptor, Carina and Sextans dwarf spheroidal galaxies. Our goal is to compare dark matter profile models of these…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 M. A. Breddels , A. Helmi

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

Developments in dynamical systems theory provides new support for the macroscale modelling of pdes and other microscale systems such as Lattice Boltzmann, Monte Carlo or Molecular Dynamics simulators. By systematically resolving subgrid…

Numerical Analysis · Mathematics 2012-01-18 A. J. Roberts , Tony MacKenzie , J. E. Bunder

We investigate a hypothesis regarding the origin of the scalelength in halos formed in cosmological N-body simulations. This hypothesis can be viewed as an extension of an earlier idea put forth by Merritt and Aguilar. Our findings suggest…

Astrophysics · Physics 2009-11-13 E. I. Barnes , L. L. R. Williams , A. Babul , J. J. Dalcanton

We discuss the structure of the ``forward visible'' (FW) parts of double and skewed distributions related to usual distributions through reduction relations. We use factorized models for double distributions (DDs) f(x, alpha) in which one…

High Energy Physics - Phenomenology · Physics 2014-11-17 I. V. Musatov , A. V. Radyushkin

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 study the distribution of dark matter in the Draco dwarf spheroidal galaxy by modelling the moments of the line-of-sight velocity distribution of stars obtained from new velocity data of Wilkinson et al. The luminosity distribution is…

Astrophysics · Physics 2009-11-10 Ewa L. Lokas , Gary A. Mamon , Francisco Prada

Recently, the distribution of velocity dispersion as far as 400kpc around red isolated galaxies was derived from statistical studies of satellites in the SDSS (Klypin & Prada 2009). This could help to constrain dark matter models at…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 F. Combes , O. Tiret

Combining the catalogue of galaxy morphologies in the COSMOS field and the sample of H$\alpha$ emitters at redshifts $z=0.4$ and $z=0.84$ of the HiZELS survey, we selected $\sim$ 220 star-forming bulgeless systems (S\'ersic index $n \leq…

Astrophysics of Galaxies · Physics 2018-01-31 M. Grossi , C. A. C. Fernandes , D. Sobral , J. Afonso , E. Telles , L. Bizzocchi , A. Paulino-Afonso , I. Matute

An iterative approach is used to construct spherically symmetric equilibrium models with an anisotropic velocity distribution. The potentialities of the method have been tested on models with known distribution functions, the…

Astrophysics · Physics 2009-11-13 N. Ya. Sotnikova , S. A. Rodionov

We describe methods for setting up self-consistent disk-bulge-halo galaxy models. The bulge and halo distribution functions (\df) are functions of $E$ and $L_z$ only. The halo's flattening and rotation can be specified. The disk \df\ is a…

Astrophysics · Physics 2016-08-30 Konrad Kuijken , John Dubinski

Finite Sample Smeariness (FSS) has been recently discovered. It means that the distribution of sample Fr\'echet means of underlying rather unsuspicious random variables can behave as if it were smeary for quite large regimes of finite…

Statistics Theory · Mathematics 2021-03-02 Benjamin Eltzner , Shayan Hundrieser , Stephan F. Huckemann

In this paper are discussed possible many body generalizations of the expanding locally anisotropic metric ansatz with respect to approximately Newtonian gravitational systems. This ansatz consistently describes local point-like matter…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-16 P. Castelo Ferreira

Understanding the nature of dark matter is among the top priorities of modern physics. However, due to its inertness, detecting and studying it directly in terrestrial experiments is extremely challenging. Numerical N-body simulations…

Astrophysics of Galaxies · Physics 2024-03-06 Zhen Li , Steen H. Hansen

A new class of a spatially homogeneous and anisotropic Bianchi type-I cosmological models of the universe for perfect fluid distribution within the framework of scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett.…

General Physics · Physics 2012-11-15 Anirudh Pradhan , Ajay Kumar Singh , H. Amirhashchi

We construct stable axially symmetric models of elliptical galaxies. The particle density on phase space for these models depends monotonically on the particle energy and on the third component of the angular momentum. They are obtained as…

Astrophysics · Physics 2009-11-07 Yan Guo , Gerhard Rein

We present predictions for the line-of-sight velocity dispersion profiles of dwarf spheroidal galaxies and compare them to observations in the case of the Fornax dwarf. The predictions are made in the framework of standard dynamical theory…

Astrophysics · Physics 2009-11-06 Ewa L. Lokas