Statistical analysis of supermassive black holes suggests that 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.
Artist's conception of the accretion disk around a spinning super-massive black hole. The rotation of the black hole may cause the high-speed jet which makes the object radio-loud [Credit: NAOJ] |
A team led by Dr. Andreas Schulze at the National Astronomical Observatory of Japan investigated the possibility that the spin of the supermassive black hole might play a role in determining if the high-speed jets form. Because black holes cannot be observed directly, Schulze's team instead measured emissions from oxygen ions [O III] around the black hole and accretion disk to determine the radiative efficiency; i.e. how much energy matter releases as it falls into the black hole. From the radiative efficiency they were able to calculate the spin of the black hole at the center.
By analyzing nearly 8000 quasars from the Sloan Digital Sky Survey, Schulze's team found that on average the O III oxygen emissions are 1.5 times stronger in radio loud quasars than in radio quiet quasars. This implies that spin is an important factor in the generation of jets.
Schulze cautions, "Our approach, like others, relies on a number of key assumptions. Our results certainly don't mean that spin must be the only factor for differentiation between radio-loud and radio-quiet quasars. 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."
The study was published in the Astrophysical Journal.
Source: National Astronomical Observatory of Japan [January 13, 2018]