Recent discovery may change our understanding of how black holes form and evolve
By Chris Wood
November 29, 2012
Astronomers from the University of Texas at Austin have measured the second-largest black hole ever discovered. It takes up some 14 percent of the galaxy's mass and may lead to an overhaul of theories regarding the formation and evolution of black holes.
The black hole was studied using the Hobby-Eberly Telescope at UT Austin, and resides in galaxy NGC 1277, some 220 million light-years away. Despite NGC 1277 being just ten percent the size and mass of our own Milky Way galaxy, the black hole at its center is around 17 billion times the size of our own Sun, making it more than 11 times the size of Neptune's orbit around the Sun.
Up until now, the size of a black hole was thought to correspond to the size of the galaxy in which it resides (generally around 0.1 percent of the galaxy's mass), with similarly massive black holes only being recorded in giant galaxies known as “ellipticals." NGC 1277's black hole turns this theory on its head, taking up 14 percent of its galaxy's mass. Karl Gebhardt from UT Austin commented on the significance of the discovery, stating that “it leads us to think that very massive galaxies have a different physical process in how their black holes grow.”
The discovery was made as part of the Hobby-Eberly Telescope Massive Galaxy Survey, an effort to catalog a sample of the most massive nearby galaxies in order to gain a greater understanding of the relationships between black holes and their host galaxies. The data collected on NGC 1277 was combined with measurements of star brightness sourced from an earlier picture taken by the Hubble Space Telescope, in order to determine the staggering size of the specimen.
Dr Van der Bosch of the Max Planck Institute for Astronomy in Germany told the BBC that the galaxy “seems to be very old ... So somehow this black hole grew very quickly a long time ago, but since then that galaxy has been sitting there not forming any new stars or anything else.”
Early this year, NASA released a report suggesting that the 20 million mph (32 million km/h) winds associated with the presence of similarly massive black holes may prevent the formation of new stars. This seems to correspond with the lack of star formation in NGC 1277, but the reason for the sheer size of the black hole remains a mystery.