On the contribution of ULXs to stellar feedback: an intermediate mass black hole candidate and the population of ULXs in the low-metallicity starburst galaxy ESO 338-4

X-rayradiation from accreting compact objects is an important part of stellar feedback. The metal poor galaxy ESO338-4 has experienced vigorous starburst during last 40 Myr and contains some of the most massive super star clustersin the nearby Universe. Given its strarburst age and its star-formation rate, ESO338-4 is one of the most efficient nearby manufactures of neutron star and black holes, hence providing the excellent laboratory for feedback studies. We used X-rayobservations with the largest modern X-ray telescopes, XMM-Newton and Chandra to unveil the most luminous accreting neutron stars and black holes in ESO338-4. We also used the comparison between the X-rayimages and spectra with integral field spectroscopic observations in the optical to constrain the nature of strong X-rayemitters. X-rayobservations uncovered three ultraluminous X-ray sourcesin ESO338-4. The brightest among them, ESO338-4 X-1, has X-rayluminosity in excess 10^{40} erg/s. We speculate that ESO338-4 X-1 is powered by accretion on an intermediate mass 300M_sun black hole. We suggest that X-rayradiation from ULXs strongly contributes to stellar feedback in this template starburst galaxy.