Over 2.5 million black holes spotted by NASA telescope

It's an astronomical bonanza: the US National Space and Aeronautics Administration's (NASA's) infrared sky-mapping telescope has discovered no less than 2.5 million black holes.

 

NASA said the black holes were discovered by NASA's Wide-field Infrared Survey (WISE) which used infrared to scan the sky from December 2009 to February 2011, Space.com reported.

 

"WISE has found a bonanza of black holes in the universe," it quoted astronomer Daniel Stern of NASA's Jet Propulsion Laboratory as saying at an Aug. 29 press briefing.

 

Having completed its mission and finally running out of coolant, the WISE telescope's operations were shut down in February 2011, but scientists are still poring through its findings.

 

The WISE telescope was able to find about three times as many black holes than comparable surveys done using visible light.

 

Space.com said these black holes are huge "supermassive" ones caught devouring matter as it fell into them.

 

These active black holes, known as quasars, are some of the brightest objects in the universe because of light released by the infalling matter, it said.

 

"We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky. We think these quasars are really important for shaping how galaxies look today," Stern said.

 

"Hot DOGs"

 

Space.com said that WISE also yielded a smaller population of rarer objects that researcher dubbed "hot DOGs," or hot, dust-obscured galaxies.

 

It said the galaxies are thought to be extremely bright, but appear very faint to us because their light is shrouded by dust.

 

WISE has so far spotted some 1,000 hot DOGs, most of them spotted from very far away.

 

This means they existed in the early days of the universe, because their light has taken billions of years to travel to Earth.

 

"It is actually the most obscured objects in the WISE sky that are among the brightest objects in the universe. They're definitely a different type of beast than we’ve seen before," said Peter Eisenhardt, a WISE project scientist at JPL.

 

Missing link

 

Space.com said the scientists suspect these objects may represent a missing link in galaxy evolution, "capturing a brief phase in the life of a galaxy that is transitioning from being a spiral disk galaxy like our milky way to what's called an elliptical galaxy."

 

While astronomers used to think spirals and ellipticals were two wholly separate classes of galaxy, researchers believe they are just two different stages of life.

 

They are considering the possibility a merger between two colliding galaxies, or some other dynamic process, may transform a spiral into an elliptical.

 

That halfway point between the two could perhaps be embodied by hot DOGs, the scientists speculate.

 

"We think we may be seeing these galaxies at a crucial transformational stage," said Rachel Somerville, an astrophysicist at Rutgers University.

 

She said the Milky Way itself could someday become a hot DOG, after it collides with the neighboring Andromeda galaxy in about two billion years.

 

Scientists also said Hot DOGs are even more luminous intrinsically than the average quasar.

 

"They may be hosting an extremely powerful supermassive black hole at their center which can heat the dust to high temperatures," said Jingwen Wu of JPL.

 

"We may be seeing a rare phase of galactic evolution where dust and gas are heated and ejected by supermassive black holes. This may be a missing link of galaxy evolution," Wu added. — TJD, GMA News