September 18, 2012

Quasars Lighting The Way For Mapping The Universe

Lee Rannals for — Your Universe Online

Researchers are finding ways to map out the spread and structure of the universe through the light of quasars.

Scientists have developed a technique that could offer up a never before seen look back to a time just after the Big Bang.

They found, while analyzing the visible light from a small group of quasars, that patterns of light variation over time were consistent from one quasar to another when corrected for the celestial object's redshift.

The team mapped out the light from 14 quasars recorded by the Massive Compact Halo Object project.

Quasar redshift takes place because as the universe carries the quasar further away, it makes the light from it appear redder, while also making the time variations appear to occur more slowly.

By measuring the rate at which a quasar's light appears to vary, and comparing this rate to the standard rate at which quasars sampled vary, the team could determine the redshift of the quasar.

Knowing this redshift enables scientists to calculate the relative size of the universe when the light was emitted, compared to today.

"It appears we may have a useful tool for mapping out the expansion history of the universe," Glenn Starkman, a physics professor at Case Western Reserve, said in a statement. "If we could measure the redshifts of millions of quasars, we could use them to map the structures in the universe out to a large redshift."

The researchers are planning to look at larger samples of quasars to confirm the patterns are consistent and can be used to calculate their redshifts everywhere throughout the universe.

If their method proves applicable, scientists could use it to trace out the growth and evolution of structure of the universe.

"This could help us learn about how gravity has assembled structure in the universe." Starkman said in the statement. "And, the rate of structure growth can help us determine whether dark energy or modified laws of gravity drive the accelerated expansion of the universe."

The team reported their findings in the journal Physical Review Letters this summer.