When The Black Hole Was Born

Tel Aviv University astronomers identify the epoch of the first fast growth of black holes.

Most galaxies in the universe, including our own Milky Way, harbor super-massive black holes varying in mass from about one million to about 10 billion times the size of our sun. To find them, astronomers look for the enormous amount of radiation emitted by gas which falls into such objects during the times that the black holes are "active," i.e., accreting matter. This gas "infall" into massive black holes is believed to be the means by which black holes grow.

Now a team of astronomers from Tel Aviv University, including Prof. Hagai Hetzer and his research student Benny Trakhtenbrot, have determined that the era of first fast growth of the most massive black holes occurred when the universe was only about 1.2 billion years old ― not two to four billion years old, as was previously believed ― and they're growing at a very fast rate.

The results will be reported in a new paper soon to appear in Astrophysical Journal.

The oldest black holes are growing the fastest
The new research is based on observations with some of the largest ground-based telescopes in the ...