Secret of distant dwarf galaxy formation revealed courtesy ISRO AstroSat; triumph for Indian research

Scientists have been exploring for a long time how galaxies, the basic building blocks of our Universe, emerged and evolved into the current ones. Now, a study by Tezpur University researchers along with an international team of astronomers from the USA and France have taken a significant step towards tracing the mysteries of galaxy formation. India's first dedicated multi-wavelength space observatory, the UltraViolet Imaging Telescope (UVIT) onboard the ISRO’s AstroSat has detected a faded emission of Far UltraViolet light in the outskirts of a sample of distant Blue Compact Dwarf galaxies. This is around 1.5-3.9 billion light-years away from the Earth.

This is first-of-its-kind research which traces how young stars found in the star-forming clusters slowly resettle towards the inner regions to build up the celestial content of these galaxies. Anshuman Borgohain, the lead author of the study published in the journal Nature, mentioned that "the occurrence of such young stars at the periphery of galaxies is usually a tell-tale signature of recent gas accretion from their surroundings that fuel the star-formation and subsequent galaxy growth.” He worked under Dr. Rupjyoti Gogoi, Assistant Professor of Physics at Tezpur University, and Prof. Kanak Saha, Professor of Astronomy at IUCAA.

However, the principal research staff in USA's IBM research division, Bruce Elmegreen who was involved in the study showed his concerns that it has always been a mystery how some small galaxies can have such active star formation. He further added that these findings show that accreting gas in the far outer parts can be forced to move inward through torques exerted by giant gas and stellar complexes. And that’s how the migration of gas builds central density during the lifetime of the galaxy.

Dr. Rupjyoti Gogoi, Assistant Professor of Physics at Tezpur University said, "AstroSat could be an inspiration to young researchers of the country." AstroSat’s imaging capabilities have extended further paths in the field of extragalactic astronomy.