On the motion of a test particle around a global monopole in a modified gravity

Abstract

In this paper we suggest an approach to analyse the motion of a test particle in the spacetime of a global monopole within a $f(R)$-like modified gravity. The field equations are written in a more simplified form in terms of $F(R)=\frac{df(R)}{dR}$. Since we are dealing with a spherically symmetric problem, $F(R)$ is expressed as a radial function $\mathcal{F}(r)\equiv F(R(r))$. So, the choice of a specific form for $f(R)$ will be equivalent to adopt an Ansatz for $\mathcal{F}(r)$. By choosing an explicit functional form for $\mathcal{F}(r)$ we obtain the weak field solutions for the metric tensor, compute the time-like geodesics and analyse the motion of a massive test particle. An interesting feature is an emerging attractive force exerted by the monopole on the particle.

7 pages, 3 figure. New version accepted for publication in Modern Physics Letters A

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• Scalar and spinor quasinormal modes of an $f(R)$ global monopole
• The fragmentation instability of a black hole with $f(R)$ global monopole under GUP
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• On the Thermodynamical Black Hole Stability in the Space-time of a Global Monopole in $f(R)$-Gravity
• Black Holes-Hedgehogs and Strings as Defects of the Universal Vacua
• The instability of a black hole with $f(R)$ global monopole under extended uncertainty principle