Article Posted on : - Jan 08, 2009

VLA image (right) of gas in young galaxy seen as it was when the Universe was only 870 million years old. CREDIT: NRAO/AUI/NSF, SDSS

NEW YORK (BNS): Astronomers have long wondered which formed first in the early Universe – the galaxies or the super massive black holes seen as their cores. The good news is that astronomers have been able to crack the code to confirm that black holes came first in the early Universe.

"It looks like the black holes came first. The evidence is piling up," said Chris Carilli, of the National Radio Astronomy Observatory (NRAO)

Carilli confirmed the findings in a lecture presented to the American Astronomical Society's meeting in Long Beach, California.

Studies of galaxies and their central black holes in the nearby Universe has revealed an intriguing linkage between the masses of the black holes and of the central ‘bulges’ of stars and gas in the galaxies. The ratio of the black hole and the bulge mass is nearly the same for a wide range of galactic sizes and ages. For central black holes from a few million to many billions of times the mass of the Sun, the black hole's mass is about one one-thousandth of the mass of the surrounding galactic bulge.

"This constant ratio indicates that the black hole and the bulge affect each others' growth in some sort of interactive relationship," said Dominik Riechers, of Caltech. "The big question has been whether one grows before the other or if they grow together, maintaining their mass ratio throughout the entire process."

Fabian Walter of the Max-Planck Institute for Radioastronomy (MPIfR) in Germany, said that they had finally been able to measure black-hole and bulge masses in several galaxies seen as they were in the first billion years after the Big Bang. Walter said that the evidence suggests that the constant ratio seen nearby may not hold in the early Universe. “The black holes in these young galaxies are much more massive compared to the bulges than those seen in the nearby Universe. The implication is that the black holes started growing first,” Walters said.