The distribution of galaxies gravitational field stemming from their tidal interaction

TL;DR

This paper derives the distribution function of gravitational fields of galaxies due to tidal interactions, revealing a non-Gaussian form and analyzing the relation between galaxy cluster mass and angular momentum.

Contribution

It introduces a discrete many-body approach using multipole expansion to model gravitational fields, extending previous statistical methods to include extended object properties.

Findings

Distribution function is non-Gaussian, dictated by interaction potential.

Theoretical analysis of galaxy cluster angular momentum-mass relation.

Comparison with observational data supports the model.

Abstract

We calculate the distribution function of astronomical objects (like galaxies and/or smooth halos of different kinds) gravitational fields due to their tidal in- teraction. For that we apply the statistical method of Chandrasekhar (1943), used there to calculate famous Holtzmark distribution. We show that in our approach the distribution function is never Gaussian, its form being dictated by the potential of interaction between objects. This calculation permits us to perform a theoretical analysis of the relation between angular momentum and mass (richness) of the galaxy clusters. To do so, we follow the idea of Catelan & Theuns (1996) and Heavens & Peacock (1988). The main difference is that here we reduce the problem to discrete many-body case, where all physical properties of the system are determined by the interaction potential V(r_ij). The essence of reduction is that we use the multipole (up to quadrupole here) expansion of Newtonian potential so that all hydrodynamic, "extended" characteristics of an object like its density mass are "integrated out" giving its "point-like" charac- teristics like mass and quadrupole moment. In that sense we make no difference between galaxies and smooth components like halos. We compare our theoretical results with observational data.