Orthogonal Eisenstein series and theta lifts

We show that the additive Borcherds lifts of vector-valued non-holomorphic Eisenstein series are orthogonal non-holomorphic Eisenstein series for O(2,l). Using this we give another proof that they have a meromorphic continuation, calculate their Fourier expansion and show that they have a functional equation analogous to the classical case. Moreover, we will investigate the image of Borcherds lift and give a sufficient condition for surjectivity.