ABSTRACT

At the highest accretion rates (above the classical Eddington limit), theoretical models and numerical simulations predict that stellar-mass black holes and neutron stars release a significant fraction of accretion power via jets and winds. Identifying examples of such powerful outflows, and measuring their kinetic power, is not as simple as identifying the most luminous X-ray sources in a survey. I will illustrate examples of ultraminous X-ray sources where the presence of thick winds is revealed from downscattering, lines and edges imprinted on the observed X-ray spectrum. I will then show examples of huge shock-ionized nebulae (size > 100 pc) around some sources: we measure the expansion velocity of the bubble and the emission from diagnostic lines to estimate the power injected by the accreting compact object. In some cases, such bubbles are also associated with radio synchrotron bubbles. Finally, I will discuss whether the jet and wind power may provide a clue to distinguish between neutron star and black hole accretors.