The distinguishing factor for gravity models: stellar population synthesis

TL;DR

This study compares stellar mass-to-light ratios derived from galaxy rotation curves with stellar population synthesis predictions to distinguish between alternative gravity models like MOND, MOG, and CDM.

Contribution

It demonstrates that stellar mass-to-light ratios can serve as a key factor to differentiate between alternative gravity theories using observational data.

Findings

MOND's $M_*/L$ ratios align with SPS predictions and favor Kroupa's IMF.

MOG's $M_*/L$ ratios are inconsistent with SPS models.

CDM shows large dispersion in $M_*/L$ ratios.

Abstract

Alternative gravitations of Milgrom (MOND), Moffat (MOG), and CDM scenarios all simulate rotation curves of spirals with reasonable details. They display significant disparities however in predicting the stellar mass-to-light ($M_*/L$) ratios of the galaxies. We maintain this feature could serve as a distinguishing factor between different alternative theories. We analyze the rotation curves of 46 low- and high-surface brightness galaxies and compare the resulting $M_*/L$s with the predictions of the Stellar Population Synthesis (SPS) scheme. The color-$M_*/L$ correlation obtained for MOND is consistent with predictions of SPS models. MOG does not show this consistency, and the $M_*/L$s of CDM model shows large dispersions. Furthermore, $M_*/L$ ratios of MOND with Bekenstein interpolating function favor Kroupa's initial mass function (IMF) of the SPS scheme, while those of MOND with standard and simple interpolating functions are consistent with Salpeter's IMF. Here is another indication to differentiate between different IMFs that are used in SPS context.