Radio Telescopes Spy Black Hole's Powerful Beams

Scientists have long thought that black holes spew excited jets of particles at light speed as part of the process of absorbing matter the giant bodies attract gravitationally. They've formed theories as to how this expulsion occurs. The best known predicts a scenario in which the high-power jets are accelerated by tightly twisted magnetic fields close to the black hole's event horizon. This was what should happen if advanced astrophysical mathematics were correct. Still, they had no direct evidence the theory matched reality. That may have now changed.

Astronomers at the U.S. National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), a networked collection of large radio telescopes stretching from the Virgin Islands to Hawaii, said today that they had detected data from a black hole that confirmed the leading theory is accurate.

In an account on the finding from the National Radio Astronomy Observatory (please see Radio Telescope Reveals Secrets of Massive Black Hole), the leader of a team that made the discovery said they recorded an "unprecedented view of the inner portion of one of these jets and gained information that's very important to understanding how these tremendous particle accelerators work."

The radio-astronomy team was led by Alan Marscher of Boston University. It trained the telescopes from 10 observatories at a galaxy called BL Lacertae (BL Lac), some 950 million light-years from Earth. BL Lac is a blazar, the most energetic type of black-hole-powered galactic core. The data they received confirmed that near the center of BL Lac, where magnetic fields are twisted by the gravitational pull and rotation of the black hole, material moving outward in this close-in acceleration region follows a corkscrew-shaped path inside the bundle of affected magnetic fields.

"That behavior is exactly what we saw," Marscher said in the statement.

"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," he noted. "This is a major advance in our understanding of a remarkable process that occurs throughout the universe."

Full results of the VLBA research team's efforts can be found in today's issue of the journal Nature.


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