Dynamics of test particles around hairy black holes in Horndeski’s theory

Abstract

We investigate charged particles’ motions around a hairy black hole of Horndeski’s theory immersed in an external magnetic field. Although the critical energy E∗2 divides the charged particle’s bounded trajectory into three types just like the situation in the classical Schwarzschild black hole, it still suggests that the values of the angular momentum and the energy for the charged particle around the hairy black hole are smaller than the ones of the classical hole. The epicyclic frequencies of the charged particle around the hairy black hole immersed in the external magnetic field are compared with the results of the observed microquasars’ results. It indicates that the influences of the hairy black hole best fits the data of the observations with a non-vanishing magnetic field. Our present work might provide hints for distinguishing the hairy black hole in Horndeski’s theory from the classical Schwarzschild black hole by using the test charged particles’ dynamics around the strong gravitational field.