Extreme UV light from galaxy detected by AstroSat can give important clue on Dark Ages: DST
AstroSat, India's first multi-wavelength satellite has detected extreme-UV (EUV) light from a galaxy 9.3 billion light-years away from Earth, uncovering an important clue on how the Dark Ages of the universe ended and how the first extreme-UV light appeared, the Department of Science & Technology (DST) said on Thursday.
Such EUV radiation has enough energy to ionise a hydrogen atom by liberating its electron from the nucleus' influence. The EUV photons emitted by galaxies like AUDFs01 could play a crucial role in reionising the early universe soon after the Cosmic Dark Age and emitting the first light.
"Scientists have uncovered an important clue on how the Dark Ages of the universe ended and how the first extreme-UV light appeared. India's first multi-wavelength satellite, AstroSat, has detected extreme-UV (EUV) light from a galaxy, called AUDFs01, 9.3 billion light-years away from Earth,” DST said.
A collaboration of researchers from different countries under a project funded by the Indo-French Centre for the Promotion of Advanced Research or CEFIPRA -- a bilateral organisation set up by the DST and the Ministry for Europe and Foreign Affairs of France -- delved into how galaxies like AUDFs01 grow their stellar mass when the first stars and galaxies became visible.
The team consisting of Prof Combes from Observatoire de Paris, Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), France, and Prof Kanak Saha from Inter-University Centre for Astronomy and Astrophysics (IUCAA), India connected by CEFIPRA estimated the recent star-formation rate and mass of the gas reservoir in the galaxy.
Star formation rate provides a quantitative measure of the stellar mass growth in galaxies. The typical star formation rate (or gas consumption rate) in those first galaxies is not known.
"By studying galaxies like AUDFs01 and many more, we could get an idea of how star formation rate, gas consumption rate, and growth of stellar mass in those primitive galaxies. Their work has been recently published in the journal 'Nature Astronomy'," it said.
The multi-wavelength satellite AstroSat, which was launched on September 28, 2015, by the Indian Space Research Organisation (ISRO) has five unique X-ray and ultraviolet telescopes working in tandem and has onboard the UltraViolet Imaging Telescope (UVIT).
According to Saha, this extreme UV wavelength regime is crucial to understand models of the stellar population, especially the massive, hot stars in early galaxies.
DST secretary Ashutosh Sharma said, "While technology is often developed and adopted keeping in view local needs, deep science is often global requiring strong international collaborations such as this one supported by CEFIPRA.
There are indeed many compelling stories of profound science resulting from India's active international collaborations in the frontier areas with over 40 countries.
(With Inputs from PTI)
