# Origin of the fundamental plane of elliptical galaxies in the Coma Cluster without fine-tuning

## TL;DR

This paper explains the tilt of the fundamental plane of elliptical galaxies in the Coma Cluster using modified Newtonian dynamics (MOND), without requiring fine-tuning, by analyzing galaxy data with specific mass models and assumptions.

## Contribution

It demonstrates that the fundamental plane tilt can be naturally explained by MOND with a simple interpolating function and realistic assumptions, avoiding fine-tuning.

## Key findings

- The tilt is explained by MOND with a simple interpolating function.
- A well-motivated anisotropic velocity distribution is assumed.
- The analysis supports the use of Kroupa or Salpeter stellar mass-to-light ratios.

## Abstract

After thirty years of the discovery of the fundamental plane, explanations to the tilt of the fundamental plane with respect to the virial plane still suffer from the need of fine-tuning. In this paper, we try to explore the origin of this tilt from the perspective of modified Newtonian dynamics (MOND) by applying the 16 Coma galaxies available in Thomas et al.[1]. Based on the mass models that can reproduce de Vaucouleurs' law closely, we find that the tilt of the traditional fundamental plane is naturally explained by the simple form of the MONDian interpolating function, if we assume a well motivated choice of anisotropic velocity distribution, and adopt the Kroupa or Salpeter stellar mass-to-light ratio. Our analysis does not necessarily rule out a varying stellar mass-to-light ratio.