In this talk, I will show a new approach to compute Hawking radiation based on on-shell scattering amplitudes. The Hawking spectrum is obtained by exponentiating a series of Feynman diagrams describing a massless scalar field scattering through a collapse background. Using semiclassical methods, we obtain a generalized an in-in generalisation of an amplitude closely connected to the Bogoliubov coefficients. Finally, I will show how subdominant one-loop correction can be interpreted as finite-size corrections sensitive to the radius of the black hole.
