Black hole spin may affect radio waves: study

WASHINGTON, Jan. 14 (Xinhua) -- The spin of the black hole may play a role in the generation of powerful high-speed jets blasting radio waves and other radiation across the universe, a study on supermassive black holes recently published in the Astrophysical Journal found.

The accretion disks around supermassive black holes (black holes with masses millions of times those of the sun) are some of the brightest objects in the universe. These objects are called "quasi-stellar radio sources" or "quasars," but actually only about ten percent of quasars emit strong radio waves.

The effects of black holes, in particular accretion disks where matter is shredded and superheated as it spirals down into the black hole, can release enormous amounts of energy.

A team led by Andreas Schulze at the National Astronomical Observatory of Japan analyzed nearly 8,000 quasars from the Sloan Digital Sky Survey, one of the most ambitious surveys in the history of astronomy, and found that on average the oxygen ion emissions are 1.5 times stronger in "radio-loud" quasars than in "radio-quiet" quasars, implying that spin is an important factor in the generation of jets.

Schulze said that "radio-loud" quasars occur when a fraction of the matter in the accretion disk avoids the final fate of falling into the black hole and comes blasting back out into space in high-speed jets emitted from the poles of the black hole.

But analysts don't understand why jets form some times and do not form other times.

"Our results certainly don't mean that spin must be the only factor for differentiation between radio-loud and radio-quiet quasars," said Schulze."The results do suggest, however, that we shouldn't count spin out of the game. It might be determining the loudness of these distant accreting monsters." Enditem