ABSTRACT
Black holes are regions of space from which light cannot escape. It might therefore appear that little could be learned about these objects from measurements of the extragalactic background light (EBL). In fact, experimental data on EBL intensity constrain black holes more strongly than any of the other dark-matter candidates. This chapter distinguishes between ‘ordinary’ black holes (which form via the gravitational collapse of massive stars at the end of their lives) and primordial black holes which could have arisen from the collapse of overdense regions in the early Universe. Black holes contribute to the EBL via a process discovered by Hawking in 1974 and often called Hawking evaporation. The chapter estimates the impact of this process on the intensity of the EBL, and also considers the corresponding problem for the higher-dimensional analogues of black holes known as solitons.
