Ultra-luminous X-ray pulsars (ULPs) are accreting neutron stars with inferred isotropic luminosities above 10^39 erg/s. They are therefore accreting orders of magnitude above their Eddington limit, challenging our current understanding of accretion physics. Currently, four ULPs have been identified through coherent pulsations, while a fifth one was revealed by the discovery of a cyclotron line in its X-ray spectrum. I will give an overview over the currently known observational facts and how they compare to other ultra-luminous X-ray sources in nearby galaxies as well as to standard X-ray binaries in our own galaxy. I will discuss the observed properties of the accretion column, as well as newly discovered outflows from the super-Eddington accretion disk and what these measurements tell us about the physics governing these sources. While current theoretical models struggle to explain all of the observational facts, I will briefly present different proposed scenarios. For a better understanding of theses sources, the search for more members is ongoing.
Please note the location: 37-187