Breaking out: How black hole jets punch out of their galaxies

A simulation of the powerful jets generated by supermassive black holes at the centers of the largest galaxies explains why some burst forth as bright beacons visible across the universe, while others fall apart and never pierce the halo of the galaxy.

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CrazyNeutrino said:

Breaking out: How black hole jets punch out of their galaxies

A simulation of the powerful jets generated by supermassive black holes at the centers of the largest galaxies explains why some burst forth as bright beacons visible across the universe, while others fall apart and never pierce the halo of the galaxy.

more…

“If the jet is not powerful enough to penetrate the surrounding gas, the jet becomes narrow or collimated, a shape prone to kinking and breaking. When this happens, the hot ionized gas funneled through the magnetic field spews into the galaxy, inflating a hot bubble of gas that generally heats up the galaxy.

“Powerful jets, however, are broader and able to punch through the surrounding gas into the intergalactic medium. The determining factors are the power of the jet and how quickly the gas density drops off with distance, typically dependent on the mass and radius of the galaxy core.

“The simulation, which agrees well with observations, explains what has become known as the Fanaroff-Riley morphological dichotomy of jets, first pointed out by Bernie Fanaroff of South Africa and Julia Riley of the U.K. in 1974.”

That makes sense. Also, and finally, it explains why these jets are so tightly collimated. I’ve done some mathematical simulations of polar jets (of a star rather than a black hole but the principle is the same) and all the simulations give jets that are much wider than those observed. From this new work I finally see that the narrowness could be due to the lack of gas drag in line with the jet centre because the jet centre has punched its way through this gas.