A long time ago in a galaxy far, far away...

No, it's not Star Wars -- it's the setting of a recent celestial discovery by a group of astronomers including a Penn State professor and two former postdoctoral fellows.

Rapid star formation and black-hole growth that took place in the early universe may have been caused by the collisions of at least 20 galaxies.

The discovery was made by overlapping images obtained at X-ray, submillimeter and optical wavelengths, said Niel Brandt, professor of astronomy and astrophysics.

Scientists combined existing data from NASA's Chandra X-ray Observatory with new data from the James Clerk Maxwell Telescope (JCMT) at the University of Hawaii, he said.

"As new people come along and study the same patches of sky at different wavelengths, new information is gathered that fits together like a multi-piece jigsaw puzzle," said Brandt, a lead researcher for Chandra observations.

A team of international researchers made the discovery, including Brandt and two former Penn State postdoctoral fellows: Franz Bauer of Columbia University and David Alexander of the University of Cambridge in England. Alexander is the lead author of the team's paper, which was published April 7 in the journal Nature.

Brandt said Chandra focused on black holes while the JCMT looked at star formation.

Submillimeter, which is relatively new, and optical observations were able to show that there was an abnormally large amount of gas in this region, and that in each of the galaxies there was accelerated star formation, Brandt said.

"A star was forming once every day," he said. "That's 100 times the rate in our own galaxy."

The galaxies studied by the research team are known as submillimeter galaxies because they were first discovered at that wavelength by the JCMT. Submillimeter wavelengths are found in the region between radio waves and infrared light on the electromagnetic spectrum, Brandt said.

Researchers suspect that most of the submillimeter galaxies are each actually two colliding galaxies, Brandt said. The collision forces the gases from each galaxy together, causing a burst of star formation, and supplying each central black hole with lots of fuel to grow.

The area was part of the Hubble Deep Field North survey, from which the deepest X-ray images have been recorded, said Donald Schneider, professor of astronomy and astrophysics.

Schneider said the telescope was exposed for 2 million seconds, and one photon would appear every few days from the farthest sources.

"The Deep Field survey is about 60 percent the size of the moon," Brandt said, "and the study focused on about one-third of that area."

In that region of space, 20 submillimeter sources were discovered, along with 16 X-ray sources, he added.

The data collected by Chandra showed that the supermassive black holes in the galaxies were also growing at the same time as this rapid star formation. This could have led to the birth of quasars -- galaxies that have the largest and most active black holes in the universe, Schneider said.

The optical images of these galaxies are incredibly faint, even though they are, intrinsically, some of the brightest sources of light, Schneider said.

"The farthest sources are around 10 billion light-years away," Brandt said.