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Most distant galaxy in universe discovered

Galaxy M101

Scientists, including one of Indian-origin, have discovered the most distant galaxy ever

Galaxy M101

File Photo

Washington: Scientists, including one of Indian-origin, have discovered the most distant galaxy ever – seen as it was 700 million years after the Big Bang – providing a snapshot of the early universe.

The galaxy is seen as it was when the universe was only about 5 per cent of its current age of 13.8 billion years, researchers said.

The team’s observations showed that the new galaxy z8 GND-5296 is forming stars extremely rapidly producing each year about 300 times the mass of our Sun.

By comparison, the Milky Way forms only two to three stars per year.

Researchers identified the very distant galaxy candidate using deep optical and infrared images taken by the Hubble Space Telescope.

Follow-up observations of this galaxy by the Keck Telescope in Hawaii confirmed its distance.

The team selected several candidates, based on their colors, from the approximately 100,000 galaxies identified in the Hubble Space Telescope images taken as a part of the CANDELS survey, the largest project ever performed by the Hubble.

“What makes this galaxy unique, compared to other such discoveries, is the spectroscopic confirmation of its distance,” said University of California, Riverside astronomer Bahram Mobasher.

“By observing a galaxy that far back in time, we can study the earliest formation of galaxies,” he said.

“By comparing properties of galaxies at different distances, we can explore the evolution of galaxies throughout the age of the universe,” said Mobasher.

By performing spectroscopy, researchers are able to accurately gauge the distances of galaxies by measuring a feature from the ubiquitous element hydrogen called the Lyman alpha transition.

It is detected in most galaxies that are seen from a time more than one billion years from the Big Bang.

Of the 43 galaxies observed, the research team detected the Lyman alpha feature from only z8-GND-5296.

The researchers suspect they may have zeroed in on the era when the universe made its transition from an opaque state in which most of the hydrogen is neutral to a translucent state in which most of the hydrogen is ionized.

“The difficulty of detecting the hydrogen emission line does not mean that the galaxies are absent,” said Naveen Reddy, an assistant professor of astronomy.

“It could be that they are hidden from detection behind a wall of neutral hydrogen,” said Reddy.

The new distance record-holder lies in the same part of the sky as the previous record-holder, which also happens to have a very high rate of star-formation.

The study was published in the journal Nature.


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