Large black holes found in small galaxies

SANTA CRUZ, Calif., Sept. 15 (UPI) -- U.S. astronomers say finding supermassive black holes in surprisingly small galaxies suggests central black holes form at an early stage in galaxy evolution.

All massive galaxies host a central supermassive black hole, but active black holes are rarely seen in small "dwarf" galaxies, researchers at the University of California, Santa Cruz, said.

"It's kind of a chicken or egg problem: Which came first, the supermassive black hole or the massive galaxy? This study shows that even low-mass galaxies have supermassive black holes," researcher Jonathan Trump said in a UCSC release Thursday.

Trump and his colleagues used the Hubble Space Telescope to study galaxies about 10 billion light-years away, meaning they were viewing those galaxies as they were when the universe was less than a quarter of its present age.

"When we look 10 billion years ago, we're looking at the teenage years of the universe. So these are very small, young galaxies," Trump said.

The findings go against what has been believed about black hole formation.

"Up to now, observations of distant galaxies have consistently reinforced the local findings -- distant black holes actively accreting in big galaxies only," UCSC astronomy and astrophysics professor Sandra Faber said.

"We now have a big puzzle: What happened to these dwarf galaxies?"

One clue may be the fact the distant dwarf galaxies are actively forming new stars.

"Their star formation rate is about 10 times that of the Milky Way," Trump said. "There may be a connection between that and the active galactic nuclei. When gas is available to form new stars, it's also available to feed the black hole."