Motion of test particles around an Einstein–dilaton–Gauss–Bonnet black hole in a uniform magnetic field

Abstract

In this work, we study the motion of a magnetized particle orbiting a static and spherically symmetric black hole immersed in an external asymptotically uniform magnetic field in Einstein–dilaton–Gauss–Bonnet gravity. Similar to the Schwarzschild case, the magnetic interaction creates a region that allows circular stable orbits near the photonic sphere, however, we show that regions in which there are no allowed solutions for circular orbits appear before the marginal stability is reached for weak magnetic interaction, namely, new criteria mark the frontier of the region of stable circular orbits for EdGB black holes. The regions of allowed stable circular orbits were calculated for different values of the dilaton–Gauss–Bonnet coupling $p$ and magnetic coupling parameter $\beta$, concluding that the increase of $p$ reduces the regions of stable circular orbits. The calculations were carried out using numerical black hole solutions and were compared with an analytical approximation with an error below 5% for $p<0.25$.