The cores of galaxies contain supermassive black holes, containing hundreds of millions of times the mass of Sun. As matter falls in, it chokes up, forming a super hot accretion disk around the black hole. From this extreme environment, the black hole-powered region spews out powerful jets of particles moving at the speed of light. Astronomers have recently gotten one of the best views at the innermost portion of the jet.
A team of astronomers led by Alan Marscher, of Boston University, used the National Radio Astronomy Observatory’s Very Long Baseline Array (VLBA) to peer at the central region of a galaxy called BL Lacertae.
“We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything we see supports the idea that twisted, coiled magnetic fields are propelling the material outward,” said Alan Marscher, of Boston University, leader of an international research team. “This is a major advance in our understanding of a remarkable process that occurs throughout the Universe,” he added.
Here’s how the theory goes. As material falls into the supermassive black hole faster than it can consume it, an accretion disk forms. This is a flattened, rotating disk that circles the black hole. The spinning interaction with the black hole creates powerful magnetic fields that twist and form into a tightly-coiled bundle. It’s these magnetic fields that blast out particles into focused beams.
The theorists expected that the region inside the acceleration region would follow a corkscrew-shaped path inside the twisting magnetic fields. Furthermore, researchers expected that light and material would brighten when it was pointed directly towards Earth. And finally, the astronomers expected that there should be a flare when material hits a stationary shock wave called the “core” after it comes out of the acceleration region.
And that’s just what the observations show. The VLBA was used to study how a knot of material was ejected out of the black hole’s environment. As the knot moved through the stationary shock wave, it flared just as the theorists had predicted.
Original Source: NRAO News Release