DYNAMICS OF CLUSTERS OF GALAXIES WITH EXTENDED F(chi) GRAVITY

Abstract

In this article, we present the results of a fourth order perturbation analysis of the metric theory of gravity f(chi) = chi^(3/2) , with chi a suitable dimensionless Ricci scalar. Such a model corresponds to a specific f(R) metric theory of gravity, where the mass of the system is included in the gravitational field's action. In previous works we have shown that, up to the second order in perturbations, this theory reproduces the flat rotation curves of galaxies and the details of the gravitational lensing in individual, groups, and clusters of galaxies. Here, leaving fixed the results from our previous works, we show that the theory reproduces the dynamical masses of 12 Chandra X-ray galaxy clusters, without the need of dark matter, through the metric coefficients up to the fourth order of approximation. In this sense, we calculate the first relativistic correction of the f(chi) metric theory and apply it to fit the dynamical masses of clusters of galaxies.

Presence of a Fundamental Acceleration Scale in Galaxy Clusters

“…Various models that modify gravity have been considered in Refs. [70][71][72][73][74][75][76][77][78][79][80][81]. However, in the case of f (R) modified gravity models, it can be shown [70,71,82] that the models are equivalent to usual gravity coupled in a non-standard way to some scalar field.…”

Extended Gravity Constraints at Different Scales

“…So it is possible to compare these calculated values with observational estimations to find the best correspondence. Note that there are a lot of activity in this field, for example [35][36][37][38][39][40][41][42][43][44].…”

Extended Gravity Constraints at Different Scales

“…Thus, it is possible to compare these calculated values with observational estimations to find the best correspondence. Note that there are a lot of activity in this field, for example, [35][36][37][38][39][40][41][42][43][44].…”

“…where m a is the mass of the a-th particle, r a is its radius vector, u µ = dx µ a /dτ a is its four velocity, dτ = √ −ds 2 /c, ds 2 = g µν dx µ dx ν is an interval, u µ u µ = −c 2 , and δ 3 ( r − r a (t)) is the 3D Dirac delta function. In the PPN approximation, these components (36) and the trace T have the following form:…”