Potentials of axisymmetric razor-thin disks

TL;DR

This paper explores the gravitational potentials of axisymmetric razor-thin disks, establishing their relation to linear mass distributions and providing models with simplified potential calculations.

Contribution

It introduces a class of disk models with potentials expressible through elementary functions, facilitating realistic disk potential construction.

Findings

Potential on one side of the disk equals that of a linear mass distribution.

Families of models with potentials given by single quadratures of elementary functions.

Many realistic disk potentials can be constructed from these models.

Abstract

We investigate the gravitational potentials generated by axisymmetric, razor-thin disks. Within certain limitations, the potential on one side of the disk is shown to be equivalent to the potential produced by a linear mass distribution along the axis perpendicular to the disk. We first establish the connection between two mass distributions that generate the same potential. We then consider all disk surface density profiles that produce the potential equivalent to those generated by linear mass distributions, specifically those defined by the elementary beta distribution and its relatives on the interval $[0,1]$, $[1,\infty)$ or $[0,\infty)$. These families of models are important because the potentials in all cases are given by, at most, a single real quadrature of elementary functions of the coordinates, and furthermore, many cases result in closed-form expressions. The potential of many realistic disks may be constructed from some combinations of these disk models.