How we discovered the strange physics of jets from supermassive black holes

Supermassive black holes, which lurk at the heart of most galaxies, are often described as "beasts" or "monsters". But despite this, they are pretty much invisible. To show that they are there at all, astronomers typically have to measure the speed of the clouds of gas orbiting those regions.

But these objects can sometimes make their presence felt through the creation of powerful jets, which carry so much energy that they are able to outshine all the light emitted by the stars of the host galaxy. We know that these "relativistic jets" are two streams of plasma (matter made up of electrically charged particles despite having no overall charge), travelling in opposite directions at velocities very close to the speed of light.

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Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray, CC BY-SA)

Jets from Centaurus A.

Source / Image Courtesy

 

Centaurus A, located at a distance of about 12 million light years from Earth, contains a gargantuan jet blasting away from a central supermassive black hole.

 

New simulations of the jets produced by rotating supermassive black holes in the cores of galaxies show how, with enough power, the corkscrewing fields (white squiggles) can force their way through surrounding gas and drill out of the galaxy, channeling hot gas into the interstellar medium (top).

Less powerful jets get stalled inside the galaxy, however, their magnetic fields breaking and dumping hot gas inside and heating up the galaxy. These stalled jets may be part of the black hole feedback mechanism that periodically halts the inflow of gas that feeds the black hole.

 

This artist’s impression illustrates how high-speed jets from supermassive black holes would look. These outflows of plasma are the result of the extraction of energy from a supermassive black hole’s rotation as it consumes the disc of swirling material that surrounds it. These jets have very strong emissions at radio wavelengths.