Oldest Galaxy EGS8p7 Discovery Is Astronomy Bonanza

Posted: Sep 7 2015, 6:33pm CDT | by , in News | Latest Science News


Oldest Galaxy EGS8p7 Discovery is Astronomy Bonanza
Courtesy of NASA/ESA/JPL-Caltech

The new discovery is challenging the established theories regarding evolution of the early universe.

A team of researchers from the California Institute of Technology (Caltech) has discovered a galaxy which they call the most distant and the oldest ever found.  The newly-discovered galaxy is named EGS8p7 and evidences suggest that it is more than 13.2 billion years old. The universe itself is 13.8 billion years old, making the galaxy almost as old as the cosmos.

The graphic images of the EGS8p7 have been captured through the Hubble Space Telescope and Spitzer Space Telescope. The galaxy looks remarkably bright and can help provide significant information regarding the evolution of early universe.

“The galaxy we have observed, EGS8p7, which is unusually luminous, may be powered by a population of unusually hot stars and it may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times.”Sirio Belli, who was involved in the project, said.

Scientists are doing a spectrographic analysis of the galaxy to determine its redshift. Redshift is used to measure the distance of the galaxies by looking at the light emitting from galaxies and celestial objects.

Immediately after the Big Bang, the universe turned into a soup of charged particles. The early universe could not transmit light or photons because these particles were scattered. 380,000 years after the universe was cooled enough to combine free electrons and protons into neutral hydrogen atoms, the light traveled through the universe. After that, galaxies ionized the neutral gas and lit up. Neutral hydrogen atoms must have absorbed certain radiation from newly forming galaxies before the reionization including Lyman-alpha line.

“If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission,” said Adi Zitrin, a NASA Hubble Postdoctoral Scholar in Astronomy. “We expect that most of the radiation from this galaxy would be absorbed by the hydrogen in the intervening space. Yet, still we see Lyman Alpha from this galaxy.”

Scientists are using MOSFIRE spectrometer, an apparatus used for measuring wavelength of a matter.

"The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the universe should be full of absorbing hydrogen clouds,” said Richard Ellis, who has recently retired from Caltech faculty and working on the project. 

The previous furthest detected galaxy had a redshift of 7.73.

"We are currently calculating more thoroughly the exact chances of finding this galaxy and seeing this emission from it, and to understand whether we need to revise the timeline of the reionization, which is one of the major key questions to answer in our understanding of the evolution of the universe," Zitrin says.

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Hira Bashir covers daily affairs around the world.




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