Abstract
The global properties of elliptical galaxies are connected through the so-called fundamental plane of ellipticals, which is an empirical relation between their parameters: effective radius, central velocity dispersion and mean surface brightness within the effective radius. We investigated the relation between the parameters of the fundamental plane equation and the parameters of modified gravity potential f ( R ) . With that aim, we compared theoretical predictions for circular velocity in f ( R ) gravity with the corresponding values from a large sample of observed elliptical galaxies. Besides, we consistently reproduced the values of coefficients of the fundamental plane equation as deduced from observations, showing that the photometric quantities like mean surface brightness are related to gravitational parameters. We show that this type of modified gravity, especially its power-law version— R n , is able to reproduce the stellar dynamics in elliptical galaxies. In addition, it is shown that R n gravity fits the observations very well, without the need for a dark matter.
Highlights
It is well established that there are three main global observables of elliptical galaxies: the central projected velocity dispersion σ0, the effective radius re, and the mean effective surface brightness Ie
It is well known that elliptical galaxies do not populate uniformly this three dimensional parameter space; they are rather confined to a narrow logarithmic plane, called the fundamental plane (FP) [1,2]
We reproduced the FP generated by the power law f ( R) gravity without considering the presence of dark matter (DM) in galaxies
Summary
It is well established that there are three main global observables of elliptical galaxies: the central projected velocity dispersion σ0 , the effective radius re , and the mean effective surface brightness (within re ) Ie. When written in logarithmic form, the two planes appear to be tilted by an angle of ∼15◦ [3] This tilt can be caused by different structural and dynamical effects in elliptical galaxies [4]. In paper [6], the authors derived accurate total mass-to-light ratios ( M/L)e and DM fractions, within a sphere of radius r = re centred on the galaxies. They tested the accuracy of the mass determinations by running models with and without.
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