The Shadow Of The Kerr Black Hole In A Plasma Environment

Black hole is one of the most popular object in theoretical study,since the general theory of relaticity was born.A lot of researchers studied the properties of block hole from different aspects in history.Of course a black hole itself cannot be seen directly but if it is in front of a luminous background or more generally,in the centre of a luminous asymptotically flat region(because of the bending of light it need not be behind the hole!)—it will cast a specific shadow.With the advance of the Event Horizon Telescope(EHT)project,the study of black hole shadow has stimulate a stirring of interest again.To study the shadow of black hole:,two methods usually be used: one is analytical,which use the Hamilton-Jacobi formalism of null geodesic;Another is numerical and a ray racing algorithm is applied.At first we use Hamilton-Jacobi Equation to research the shadow of Kerr black hole in vacuum environment,the size and the shape of the shadow depend on the mass and the angular momentum,and they can also depend on other parameters specific of the particular model adopted.Then we investigate the shadow of Kerr black hole with plasma by Ray-Tracing Algorithm.We discover that shape and size of shadow will effected by properties of plasma.The study of black hole shadow can not only used to explore the property of space-time in the vicinity of a black hole,but also to test the general theory of relativity.