Ultraluminous X-ray sources (ULXs) are stellar-mass compact objects accreting at super-critical rates. Some of their accretion power is released as kinetic energy of winds and/or jets. Understanding the behaviour of such objects (for example, the structure of the accretion flow and jet, and the ratio between radiative and kinetic power) gives important clues on the feedback effect of black holes onto their environment (including for example in high-redshift quasars). Evidence of powerful winds near the compact objects (~100 Schwarzschild radii) can be seen in the absorption and emission lines imprinted on the X-ray emission. At much larger scales (100 pc ~ 1E14 Schwarzschild radii), winds and jets transfer their kinetic power to the interstellar medium, creating large bubbles of shock-ionized gas, larger and brighter than ordinary supernova remnants. In the past, some of those bubbles were mistakenly attributed to hypernovae. In my talk, I will focus on some of the most interesting examples of ULX bubbles (including recent, still unpublished results). I will illustrate how we can constrain the kinetic power and the life span of a ULX from its bubble.
Ionized bubbles and kinetic power of ULXs