Posted on | June 17, 2011 | Comments Off
Using the most sensitive X-ray image ever taken, Mānoa astronomer Ezequiel Treister and colleagues have found the first direct evidence that black holes existed when the universe was less than a tenth of its present age. Between 30 and 100 percent of the 200 distant galaxies they observed contained a central black hole that was voraciously consuming the gas and stars that surrounded them.
“Black holes are objects whose gravity is so strong that not even light can escape from them. Until now, we had no idea what the black holes in these early galaxies were doing—or if they even existed,” says Treister, lead author of the study that appears in this week’s Nature. “Now we know they are there and they are growing like gangbusters.”
“It appears we’ve found a whole new population of baby black holes,” says co-author Kevin Schawinski of Yale University. “We think these babies will grow by a factor of about a 100 or a 1,000, eventually becoming like the giant black holes we see today almost 13 billion years later.”
A population of very young black holes in the early universe had been predicted, but not yet observed. Detailed calculations show that the total amount of black hole growth observed by this team is about a hundred times higher than recent estimates.
Because these very young black holes are nearly all enshrouded in thick clouds of gas and dust, optical telescopes frequently cannot detect them. However, the high energies of X-ray light can penetrate these veils, allowing the black holes inside to be studied. This discovery was made with NASA’s orbiting Chandra X-ray Observatory.