We use the integrated spectrum of the X-ray background and quasars' spectral energy distribution to derive the contribution of quasars to the energy output of the universe. We find a lower limit for the energy from accretion onto black holes of 7% of the total luminosity of the universe and probably more, with 15% quite possible. Comparing these values with the masses of black holes in the center of nearby galaxies, we show that the accretion process must be, on average, very efficient: at least 15% of the accreted mass must be transformed into radiated energy. This further implies that most supermassive black holes are rotating rapidly.
Most Supermassive Black Holes Must Be Rapidly Rotating
2002
Abstract
We use the integrated spectrum of the X-ray background and quasars' spectral energy distribution to derive the contribution of quasars to the energy output of the universe. We find a lower limit for the energy from accretion onto black holes of 7% of the total luminosity of the universe and probably more, with 15% quite possible. Comparing these values with the masses of black holes in the center of nearby galaxies, we show that the accretion process must be, on average, very efficient: at least 15% of the accreted mass must be transformed into radiated energy. This further implies that most supermassive black holes are rotating rapidly.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
