Influence Of Dark Matter Research Articles

Dynamical modelling of the elliptical galaxy NGC 2974

In this paper we analyse the relations between a previously described oblate Jaffe model for an ellipsoidal galaxy and the observed quantities for NGC 2974, and obtain the length and velocity scales for a relevant elliptical galaxy model. We then derive the finite total mass of the model from these scales, and finally find a good fit of an isotropic oblate Jaffe model by using the Gauss-Hermite fit parameters and the observed ellipticity of the galaxy NGC 2974. The model is also used to predict the total luminous mass of NGC 2974, assuming that the influence of dark matter in this galaxy on the image, ellipticity and Gauss-Hermite fit parameters of this galaxy is negligible within the central region, of radius 0.5Re.

THE INFLUENCE OF DARK MATTER HALO ONTO EVOLUTION OF SUPERMASSIVE BLACK HOLE

The influence of dark matter (DM) on the growth of supermassive black holes (SMBHs) is studied. It is shown that gravitational scattering of DM particles on bulge stars leads to diffusion of DM in phase space {m, mz, I} (m denotes the angular momentum and I is the radial action). Appropriate diffusion coefficients are calculated for different bulge models, and it is argued that the diffusion along m axis is the most important effect. It is shown that this process leads to noticeable flow of DM into the black hole (BH), resulting in its power-law growth: M bh ∝ t9/16. Comparison with observational data shows that, in principle, this effect may explain observed masses of SMBHs. Special attention is paid to the corrections related to the innermost region of BH gravitational influence and the diffusion along I axis. Their influence on the BH growth law is shown to be negligible.

Note on the influence of dark matter on the motion of the solar system

The influence of dark matter on the motion of the solar system is reinvestigated. The influence is proved to be several orders of magnitude smaller than effects that are detectable at the present time.

The influence of dark matter on the chemical evolution of elliptical galaxies

We have computed detailed models for the chemical evolution of elliptical galaxies in the presence of dark matter. These models assume that a galactic wind develops as a result of the energy injection into the gas by supernovae, and that no star formation takes place afterward. We have found that the occurrence of galactic winds is strongly affected by the presence of dark matter if this is distributed like the luminous one

Dark matter influence on velocity dispersion profiles of clusters of galaxies

We have performed a series ofN-body experiments including the effects of a massive dominant background which follows Schuster's density law in order to simulate clusters of galaxies in which a smoothly distributed dark component is present. The existence of this background is inferred from the weak luminosity segregation observed in clusters which, however, show several characteristics of well-relaxed systems. The comparison of the velocity dispersion profiles of three clusters of galaxies (Coma, Perseus, and Virgo) with those obtained in the numerical experiments allows us to place some constraints on both the distribution and amount of distributed dark material in these clusters. The profiles are rather insensitive to variations in the ratio of the background mass to the mass attached to galaxies (Mb/Mg), but exhibit a strong dependence on their relative concentration. We conclude that highly concentrated background models are not consistent with observations. We find a maximum value for the ratio of the gravitational radius of the galaxies and the background (Rg/Rb) (approximately 0.6) and using previous results (Navarroet al., 1986) we conclude that virial theorem masses underestimate the total mass (Mb+Mg) of the clusters. As a final result, we derive a minimum value for theMb/Mg ratio. All these conclusions could apply in general if Coma, Perseus, and Virgo constitute a fair sample of the rich clusters of galaxies in the Universe.