Circular orbits and accretion process in a class of Horndeski/Galileon black holes

In this paper the geodesics motion and accretion process around a subclass of Horndeski/Galileon black holes are investigated. Firstly, we present spherically symmetric geometries in a Horndeski/Galileon black hole spacetime by considering an isothermal fluid around the black hole. Then we focus on three main issues: in the first step circular orbits of test particles and their stability in equatorial plane are examined in details. Then, by treating perturbations via restoring forces, oscillations of particles around the central object are studied. Finally, the accretion process, the critical speed of the flow and accretion rate are investigated in this setup properly.