Surface Density of Disk Galaxies in MOND

TL;DR

This paper investigates the surface density of disk galaxies within the MOND framework, confirming a quasi-universal surface density for high-density galaxies and identifying different behavior for low-density ones.

Contribution

It extends Milgrom's earlier work by modeling spiral galaxies with double exponential disks, confirming the existence of a universal surface density in the MOND regime.

Findings

Universal surface density for high-density galaxies

Different behavior observed in low-density galaxies

Extension of Milgrom's point mass model to disk galaxies

Abstract

In this paper, we extend a paper by Milgrom (2009, MNRAS 398, 1023) dealing with the existence of a quasi-universal surface density for object of all mass and structure, if they are in the Newtonian regime, i.e., that their mean acceleration is larger than MOND typical acceleration $a_0$. This result is in agreement with Donato et al. (2009)'s results, claiming the existence of a quasi-universal surface density in all masses in galaxies. The Milgrom paper also predicts that objects with mean inner acceleration smaller than the values discussed do %es not show the quasi-universal behavior of the surface density discussed. In the present paper, we extend the result of Milgrom's paper, based on a point mass model, considering spiral galaxies, modelled with a double exponential disk. Similar to Milgrom's results, we find the existence of a universal surface density for galaxies with large surface density, and a different behavior for galaxies having small surface density.