The N-soliton solutions of the sine-Gordon equation with self-consistent sources

The hierarchy of the sine-Gordon equation with self-consistent sources is derived by using the eigenfunctions of recursion operator. The bilinear form of the sine-Gordon equation with self-consistent sources is given and the N-soliton solutions are obtained through Hirota method and Wronskian technique, respectively. Some novel determinantal identities are presented to treat the nonlinear term in the time evolution and finish the Wronskian verifications.