Forever blowing bubbles

I’m sure you’re all aware of quasars and active galactic nuclei in which supermassive black holes at the centre of galaxies collect in stars and other material, swirl them around an accretion disc and then emit jets of x-rays and particles as part of the dynamical process in swallowing as much of the material as possible. But how about micro-quasars? These are just ordinary black holes doing the same sort of thing on a smaller scale, perhaps nibbling on a single star. A dozen or so of these things have been found in the Milky Way galaxy.

One microquasar, located 12 million light years away in the galaxy NGC 7793, has proven to be a bit brighter than any of those previously seen. Tens to hundreds of times brighter. The black hole is pumping out enormous jets energetic particles and evacuating a large volume of space, blowing out a massive bubble of gas, 1,000 light years across, that has expanded a good hundred times farther than comparable known microquasars. The system was observed using the Chandra X-ray Space Telescope and ESO‘s Very Large Telescope. The results surprised astronomers who had previously assumed most of the energy coming from these things took the form of photons rather than accelerated particles in jets.

From the size and expansion rate of the bubble, the system is estimated at 200,000 years in age and likely to last 100,000 to a few million years more before it switches off, leaving behind an energetic sort of planetary nebula.

Full story in Universe Today.


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