Critical orbits in Schwarzschild black hole with quintessence and string cloud background space-times

Abstract: In this paper, we have examined the geodesic structure of the spacetime surrounding Schwarzschild black holes in the presence of a quintessence field parameter $q$ and string cloud parameter $a$. Because of the quintessence field, there are two horizon structures and coordinate time $t$ shows some fascinating variations due to the parameters. We do a thorough investigation of the existence of critical orbits for various parameter values.