Super-Eddington Pulsars and Ultraluminous X-ray Sources

Ultraluminous X-ray sources are an enigmatic population of X-ray binary with luminosities that exceed the Eddington limit for a standard 10 Msun stellar remnant black hole. Following a series of remarkable recent discoveries, primarily led by the NuSTAR X-ray observatory, we now know that some of the most luminous members of this population are actually powered by highly super-Eddington pulsars. These remarkable sources can reach apparent X-ray luminosities of 500 Eddington, making them the most extreme persistent accretors known! I will discuss the broadband X-ray characteristics of the known pulsar ULXs and their connection with the broader ULX population, focusing in particular on the implications for the demographics of the accretors powering these sources.