The Business Inside: India’s AstroSat Helped Global Scientists team discover one the Earliest Galaxies in Extreme UV Light

In the recent events, India’s first multi-wavelength satellite, AstorSat, has successfully detected an extreme UV light from the galaxy. This galaxy is approximately 9.3 billion light-years away from our planet Earth. The statement was justified by the Pune based Inter-University Centre from Astronomy and Astrophysics on Monday.

The five unique X-ray and Ultraviolet telescopes of AstroSat detected an extreme UV light from the AUDFs01 galaxy, situated 9.3 billion light-years away from the Earth. The international team of astronomers led by Dr. Kanak Saha, Associated Professor of Astronomy, IUCAA, made this splendid discovery and published on 24th August in Nature Astronomy. Scientists from different nations such as India, France, Netherlands, Japan, the USA, and Switzerland took part in this research. They observed the galaxy located in the Hubble Extreme Deep field through AstroSat.

While addressing The Indian Express reporters, Dr. Saha Told that his team observed the galaxy, which lasted for more than 29 hours in October 2016. But the data was way-too-huge and it took us nearly 2 years to carefully analyze it to ascertain that the emission of UV rays was indeed from the galaxy. The Director of IUCAA, Dr. SOmak Raychaudhury, further added that it is an important clue to how the dark ages of the Universe might have ended and how the light was formed. We are trying to find when all this started and how, but it’s been very difficult to find the earliest sources of light.

Before 2016, NASA Hubble Space Telescope was unable to detect any UV emission (with energy greater than 13.6 eV) from this galaxy because it was too far away and was very faint. But AstroSat was able to detect it because of the background noise in the UVIT detector is less compared to HST.

Theory of Universe Formation

In a statement disclosed by IUCAA, they mentioned that after the events of Big Bang ended, the Universe became a hot soup of particles, like neutrons, electrons, and protons. As such, it started to cool down slowly, the neutrons and protons began combining into ionized atoms of hydrogen, and eventually, som turned into helium. The ionized particles of helium and hydrogen attracted electrons, turning into neutral atoms. For the first time, it allowed light to travel freely, as it was no longer scattering-off free electrons. The universe overcame the state of opaque, but still, stars and galaxies were not formed. The Universe was still a dark place.

Then approximated a few hundred million years after the Big Bang, the dark ages came to an end when the first galaxies and stars formed. The energy pouring out from these stars and galaxies ionized the helium and hydrogen, which split the atom back into electrons and protons, known as the epoch of reionization.

So the astronomers all around the world are looking for the signs that direct towards the theory of reionization of the early universe. The usual suspects are the newborn small galaxies, but it’s difficult to observe the ionizing radiation from these sources. So the fact that AstroSat managed to detect the fraction of extreme-UV photons is a very big feast for space scientists. The co-author Dr. Akio Inoue, Professor of Waseda University Japan, said: “In the later epoch, the intergalactic absorbers decrease and we have a chance to detect such photons, but it is still like a lottery.”

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