A 300-parsec-long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793

The power behind nebula S26 The spiral galaxy NGC 7793 contains a huge radio and optical nebula, named S26. Ultraluminous X-ray sources of this class are the most luminous type of stellar-mass black holes, often associated with shock-ionized nebulae, generally with no evidence of collimated jets. Based on observations from the Chandra X-ray telescope, together with optical and radio data, Pakull et al . show that the S26 nebula is powered by a collimated pair of jets originating from the central black hole. Bright X-ray hot spots and radio lobes mark the extremities of the jets, which are surrounded by a 300-parsec-long bubble of plasma. These jets are the most powerful known so far in non-nuclear black holes, and their properties show that some black holes may channel most of their accretion power into mechanical energy rather than radiation. Ultraluminous X-ray sources are the most luminous class of black hole located outside the nuclei of active galaxies. They are often associated with shock-ionized nebulae, though with no evidence of collimated jets. Now, however, it is reported that the large nebula S26 in the nearby galaxy NGC 7793 is powered by a black hole with a pair of collimated jets. The jets seem to be 10 4 times more energetic than the X-ray emission from the core. Black-hole accretion states near or above the Eddington luminosity (the point at which radiation force outwards overcomes gravity) are still poorly known because of the rarity of such sources. Ultraluminous X-ray sources 1 are the most luminous class of black hole ( L X ≈ 10 40 erg s −1 ) located outside the nuclei of active galaxies. They are likely to be accreting at super-Eddington rates, if they are powered by black holes with masses less than 100 solar masses. They are often associated with shock-ionized nebulae 2 , 3 , though with no evidence of collimated jets. Microquasars with steady jets are much less luminous. Here we report that the large nebula S26 (ref. 4 ) in the nearby galaxy NGC 7793 is powered by a black hole with a pair of collimated jets. It is similar to the famous Galactic source SS433 (ref. 5 ), but twice as large and a few times more powerful. We determine a mechanical power of around a few 10 40 erg s −1 . The jets therefore seem 10 4 times more energetic than the X-ray emission from the core. S26 has the structure of a Fanaroff–Riley type II (FRII-type) active galaxy: X-ray and optical core, X-ray hot spots, radio lobes 6 and an optical and X-ray cocoon