The shadow of Kerr-Newman black hole surrounded by perfect fluid matter in Rastall gravity

Abstract

Abstract We investigate analytically the apparent shadows cast by Kerr-Newman black hole with surrounding perfect fluid matter in Rastall gravity theory. With the help of the Hamilton-Jacobi equation and Carter constant separable method, we derive the null geodesics of the black hole space-time and calculate the numerical results of the horizon structures. The results reveal that three horizons (Cauchy horizon r −, event horizon r + and cosmological horizon r q ) occur in the space-time, and the horizon structure could degenerate while the Rastall parameter k λ arrives the critical value. By fixing the value of equation state parameter ω ˜ of surrounding substance for both cases of dark matter ( ω ˜ = − 1 / 3 ) and dark energy ( ω ˜ = − 2 / 3 ), we study the effects of the perfect fluid matter intensity N s , the Rastall parameter k λ, the black hole spin a and the black hole charge Q on black hole shadows in detail. Furthermore, the effective potentials for black hole space-time and the energy emission rate of the black hole are also conducted and discussed.