Description
Understanding the possible observational features of black holes in quantum theory is a promising avenue to bridge the theoretical formulation of quantum gravity and astrophysical observations. In this talk, I will consider models of compact objects in the presence of horizon-scale quantum modifications, in which the objects have no horizon in the usual sense. Focusing on the shadow images of these objects, I will discuss possible observational signatures of these horizon-scale modifications. In particular, it turns out that the absence of a horizon, under certain assumptions on the surrounding emission profiles, universally results in an excess intensity within the inner shadow of the images in a model-dependent manner. The excess intensity within the inner shadow could be a model-independent image feature to probe horizon-scale quantum effects.