Astronomers claim discovery of most distant galaxies yetDecember 25th, 2009 - 1:58 pm ICT by ANI
London, December 25 (ANI): In a new research, astronomers have found tentative evidence of the most distant galaxies yet, which have redshifts of around 10.
In the near infrared, astronomers can detect galaxies that are so distant, and receding so quickly, that their light is stretched longer - or redder - than visible light.
The more distant an object, the more its light is shifted red and the higher its ‘redshift’.
In August this year, NASA’s Hubble Space Telescope made the deepest image ever of the Universe in near-infrared wavelengths using its new set of eyes, the Wide Field Camera 3 (WFC3) installed by astronauts in May.
For the past few months, researchers have been poring over this new data set - a sliver of sky about one-twelfth the diameter of the full Moon, viewed for 173,000 seconds over four days - searching for ancient galaxies that might deepen understanding of how the Universe evolved.
The current record-holder for distance is a gamma ray burst, discovered in April, with a redshift of 8.2.
Now, astronomer Garth Illingworth at the University of California, Santa Cruz, and his colleagues have found tentative evidence of three galaxies with redshifts of around 10.
These would have existed when the Universe was just 3-4 percent of its current age, and would be among the oldest objects ever seen.
“Even though it’s not really unexpected, finding galaxies at such early times is hugely exciting,” said Illingworth, who also helped to create the publicly available Hubble image and data set.
“There’s no smoking gun, but we’re confident that this is what we’re really seeing,” he added.
The lack of many bright galaxies at redshift 10 offers clues to what kicked off the Universe’s “reionization epoch” - a period between 500 million and 1 billion years after the Big Bang during which luminous objects such as galaxies and quasars ionized the intergalactic medium.
The lack of bright galaxies at the start of this timespan suggests that they did not initiate the reionization process, according to Rogier Windhorst at Arizona State University in Tempe.
“There are still a lot of questions to address,” said Illingworth. “This is very tantalizing, but we need to understand the properties of those galaxies. That’s where the real scientific interest is,” he added. (ANI)
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