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We show that the observed upper bound on the line-of-sight velocity dispersion of the stars in an early-type galaxy, sigma<400km/s, may have a simple dynamical origin within the LCDM cosmological model, under two main hypotheses. The first…

Astrophysics · Physics 2009-11-07 Abraham Loeb , P. J. E. Peebles

We argue that the stellar velocity dispersion observed in an elliptical galaxy is a good proxy for the halo velocity dispersion. As dark matter halos are almost completely characterized by a single scale parameter, the stellar velocity…

Astrophysics of Galaxies · Physics 2015-11-17 Paul L. Schechter

The self-consistent spatial distribution of particles of Galactic dark matter is derived including their own gravitational potential, as also that of the visible matter of the Galaxy. In order to reproduce the observed rotation curve of the…

Astrophysics · Physics 2009-10-28 R. Cowsik , Charu Ratnam , P. Bhattacharjee

The kinematical properties of elliptical galaxies formed during the mergers of equal mass, stars+gas+dark matter spiral galaxies are compared to the observed low velocity dispersions found for planetary nebulae on the outskirts of…

Astrophysics · Physics 2009-11-11 Felix Stoehr , Gary A. Mamon , Avishai Dekel , Thomas J. Cox

The circular velocities of the inner region of disk galaxies are predicted by standard physics but velocities beyond the stellar disks are not consistent with Newtonian physics if the material there is in stable circular orbits. However,…

Astrophysics of Galaxies · Physics 2023-09-19 Earl Schulz

We investigate the velocity distribution of elliptical galaxies in the framework of Non-local Gravity. According to this approach, it is possible to recover the fundamental plane of elliptical galaxies without the dark matter hypothesis.…

General Relativity and Quantum Cosmology · Physics 2022-09-07 D. Borka , V. Borka Jovanović , Salvatore Capozziello , P. Jovanović

The spatial distribution of stars in a disk of a galaxy can be described by a radial scale length and a vertical scale height. The ratio of these two scale parameters contains information on the axis ratio of the velocity ellipsoid, i.e.…

Astrophysics · Physics 2007-05-23 P. C. van der Kruit , R. de Grijs

Recent studies have found that the oldest and most luminous galaxies in the early Universe are surprisingly compact, having stellar masses similar to present-day elliptical galaxies but much smaller sizes. This finding has attracted…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Pieter G. van Dokkum , Mariska Kriek , Marijn Franx

Equations of motion, in cylindrical co-ordinates, for the observed rotation of gases within the gravitational potential of spiral galaxies have been derived from Carmeli's Cosmological General Relativity theory. A Tully-Fisher type relation…

Astrophysics · Physics 2007-05-23 John G. Hartnett

We derive a formula for the velocity distribution of an axially symmetric galaxy where the mass density is corrected using the mass formula from special relativity. We take some reasonable test mass densities and numerically compute the…

General Relativity and Quantum Cosmology · Physics 2023-02-21 Jaroslaw S. Jaracz

I review observational data on the kinematic properties of dwarf spheroidal galaxies in the halo of the Milky Way and beyond. The present data confirm previous claims that these galaxies have unusually large central velocity dispersions.…

Astrophysics · Physics 2007-05-23 Mario Mateo

A kinematical analysis applied to a sample of galaxy clusters indicates that the differences between the velocity distribution of elliptical and spiral galaxies are associated with the shape of their orbit families. The orbital anisotropies…

Astrophysics · Physics 2016-08-30 A. C. Ramirez , R. E. de Souza

We have selected 42 elliptical galaxies from the literature and estimated their velocity dispersions at the effective radius ($\sigma_{\re}$) and at 0.54 effective radii ($\vff$). We find by a dynamical analysis that the normalized velocity…

Astrophysics · Physics 2009-10-31 Yu-Chung N. Cheng , Lawrence M. Krauss

In a recent Letter, Cowsik, Ratnam and Bhattacharjee (1996a) have built a dynamically self-consistent spatial distribution of particles of galactic dark matter. They have come up with the rather unorthodox conclusion that the mean velocity…

Astrophysics · Physics 2011-05-23 O. Bienaymé , C. Pichon

The standard method of measuring the galaxy pairwise velocity dispersion on small scales is heavily weighted by the densest regions in a way that is difficult to calibrate. We propose a new statistic which measures the small-scale velocity…

Astrophysics · Physics 2009-10-30 Michael A. Strauss , Jeremiah P. Ostriker , Renyue Cen

Recent progress is summarized on the determination of the density distributions of stars and dark matter, stellar kinematics, and stellar population properties, in the extended, low surface brightness halo regions of elliptical galaxies.…

Astrophysics of Galaxies · Physics 2015-05-20 Ortwin Gerhard

Theories of stellar orbit diffusion in disk galaxies predict different rates of increase of the velocity dispersions parallel and perpendicular to the disk plane, and it is therefore of interest to measure the different velocity dispersion…

Astrophysics · Physics 2015-06-24 J. Gerssen , K. Kuijken , M. R. Merrifield

We examine the peculiar velocity distribution function of galaxies in cosmological many-body gravitational clustering. Our statistical mechanical approach derives a previous basic assumption and generalizes earlier results to galaxies with…

Astrophysics · Physics 2009-11-10 Bernard Leong , William Saslaw

In this paper we study a stellar dynamic model for the stars' rotational-dynamics, with a distribution of its own mass, rotating around its center with a higher density, like spiral galaxies happen, by means of a classical calculus of the…

Astrophysics · Physics 2019-09-10 E. Lopez-Sandoval

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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