India’s AstroSat Discovers Extreme Ultraviolet Light From Far Off Galaxy

Bhubaneswar: India’s first multi-wavelength satellite, AstroSat has detected an extreme ultraviolet light coming from one of the earliest galaxies. The galaxy is 9.3 billion light-years away from Earth.

Scientists from the Inter-University Centre for Astronomy and Astrophysics (IUCAA) on Monday achieved a major breakthrough when they discovered an extreme UV light from a galaxy called AUDFs01 with the help of an Indian satellite, AstroSat.

The discovery was led by Dr Kanak Saha, associate professor of astronomy at the IUCAA. It was published on August 24 by Nature Astronomy and comprised scientists from India, France, Switzerland, the US, Japan and the Netherlands.

The team led by Saha observed the galaxy located in the Hubble Extreme Deep field, through AstroSat. These observations lasted for more than 28 hours in October 2016, an official release by IUCAA said.

But it took nearly two years since then to carefully analyse the data to ascertain that the emission is indeed from the galaxy. Since UV radiation is absorbed by Earth’s atmosphere, it has to be observed from space, it said, reported The Week.

Earlier, NASAs Hubble Space Telescope (HST), significantly larger than the UVIT (UV imaging telescope), did not detect any UV emission (with energy greater than 13.6 eV) from this galaxy because it is too faint, the release said.

“AstroSat/UVIT was able to achieve this unique feat because the background noise in the UVIT detector is much less than the ones on HST,” Saha said.

Saha also added that they knew it would be an uphill task to convince the international community that UVIT has recorded extreme-UV emission from this galaxy when more powerful HST has not.

“This is a very important clue to how the dark ages of the universe ended and there was light in the universe,” said Dr Somak Raychaudhury, Director of IUCAA.

“We need to know when this started, but it has been very hard to find the earliest sources of light. I am very proud that my colleagues have made such an important discovery,” Raychaudhury added.