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

Abstract

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.

Quantum corrections to the accretion onto a Schwarzschild black hole in the background of quintessence

“…where A 2 is an integration constant. In this framework, the mass flux equation can be written as follows [55]:…”

“…In this setup, we choose the isothermal fluids which have a constant temperature. Such fluids can flow at a constant temperature [55]. Hence, their equation of state is of the form p = ωρ, in which ω is the equation of state parameter.…”

“…One can integrate the flux of the fluid over the surface of the KS black hole, S to obtain its mass rate through the accretion process (for more details see Ref. [55]) in the formṀ ≡ dM dt = − T r t dS, where dS = √ −g dθ dφ is the black hole surface element and g is the determinant of the metric tensor, g μν . From Eq.…”

“…From Eq. 18, one can deduce a relation for the mass of the black hole as a function of its initial mass, M i and t as follows [55]:…”

“…Accretion has been analyzed in various cases in the literature, including accretion onto the SCH black hole, onto a Kerr-Newman black hole [48][49][50], onto a Reissner-Nordström (RN) black hole, onto the Reissner-Nordström-de Sitter (RNdS) black hole, onto the KSL black hole [36], etc. [51][52][53][54][55].…”