Space-time structures, light trajectories and shadows for Kerr-Newman-AdS black hole with surrounding perfect fluid matter in Rastall gravity

Abstract

We present the horizon structures and the shadows for Kerr-Newman-AdS black hole located in perfect fluid matter field in Rastall gravity. By considering the Hamilton-Jacobi equation and Carter constant separable method, we obtain the null geodesic equations of the black hole space-time as well as the unstable circular photon orbits in terms of the impact parameters. The horizon structures of the space-time are calculated numerically. The results show that there are four roots for a general case of the horizon equation (the Cauchy horizon , the event horizon , the cosmological horizon rq of Rastall gravity and the cosmological horizon rc of cosmological constant), which lead to a specific characteristic with the subregions of the space-time. The influences of the cosmological horizons rq and rc on the light trajectories around the black hole are also investigated. Furthermore, we study the effects of the parameters, including the perfect fluid matter intensity Ns, the Rastall parameter kλ, the cosmological constant Λ, the black hole spin a and the black hole charge Q on black hole shadows in detail.