Black holes predate galaxies scientists say, solving age-old riddle

Black holes found at the center of galaxies around the cosmos seem to have appeared first not the other way around, scientists say, solving an age-old riddle which long has dogged astronomers.

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

Carilli outlined the research conducted by an international team of astronomers at a meeting Wednesday of the American Astronomical Society's meeting in Long Beach, California.

Scientists long have believed that a link exists between galaxies and black holes, but in a classic "chicken or egg" conundrum, were uncertain about which came first.

Researchers were particularly intrigued by a link between masses of the black holes and the central "bulges" of stars and gas in galaxies, said Dominik Riechers of the California Institute of Technology.

"The black hole and the bulge affect each others' growth in some sort of interactive relationship," Riechers said.

"The big question has been whether one grows before the other or if they grow together, maintaining their mass ratio throughout the entire process."

The research appears to have solved the mystery, using the National Science Foundation's Very Large Array radio telescope and the Plateau de Bure Interferometer in France to peer far back into the 13.7 billion-year history of the universe.

"We finally have 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, and the evidence suggests that the constant ratio seen nearby may not hold in the early universe," said Fabian Walter of the Max-Planck Institute for Radioastronomy (MPIfR) in Germany.

"The black holes in these young galaxies are much more massive compared to the bulges than those seen in the nearby universe," he said. "The implication is that the black holes started growing first."

The researchers said the next challenge is to figure out precisely how the black hole and the bulge affect each others' growth.

"To understand how the universe got to be the way it is today, we must understand how the first stars and galaxies were formed when the universe was young," Carilli said.

"With the new observatories we'll have in the next few years, we'll have the opportunity to learn important details from the era when the universe was only a toddler, compared to today's adult."