Indian astrophysics researcher discovers evidence of third largest galaxy in the universe

This discovery and its method will now pave the way for the discovery of other galaxies that have been cannibalised by other larger ones.

New Delhi: An Indian Catholic priest and astrophysics researcher has found conclusive evidence of a long lost galaxy, the third biggest after Andromeda and the Milky Way. He said that like many others before him, he nearly gave up on the search.

Fr Richard D’Souza is a Jesuit priest from Mapusa in Goa. He is a staff astronomer attached to the Vatican observatory in Rome, currently pursuing his post-doctoral research at the University of Michigan’s Department of Astronomy.

Speaking form the University of Michigan USA, where he made the discovery, D’Souza told Hindustan Times how the journey seemed destined for disappointment until they made the breakthrough.

“People had given up on this and had moved to other problems. We kept plodding along, and finally we had a breakthrough. We realised that we had to unlearn and abandon so many things we thought we knew,” Fr D’Souza told the national daily.

A galaxy like Andromeda was expected to have consumed hundreds of its smaller companions, therefore the researchers thought this would make it difficult to learn about any single one of them.

This discovery and its method will now pave the way for the discovery of other galaxies that have been cannibalised by other larger ones.

Using new computer simulations, the scientists were able to understand that even though many companion galaxies were consumed by Andromeda, most of the stars in the Andromeda’s outer faint halo were mostly contributed by shredding a single large galaxy, reported HT.

“My research centers on how galaxies grow through mergers. A galaxy like Andromeda, our nearest big neighbour, is thought to have merged with hundreds of smaller galaxies. These smaller galaxies are destroyed in the process due to tidal forces of gravity leaving behind a trail of stellar debris (like ‘crumbs’) around the main galaxy called its stellar halo,” said D’Souza to Firstpost.

He along with fellow researcher Eric Bell hit upon conclusive evidence of galaxy named M32p that was “shredded and cannibalised” by the Milky Way’s galactic neighbour Andromeda about two billion years ago.

This disrupted galaxy was the third-largest member of the local group of galaxies, after the Milky Way and Andromeda galaxies. D’Souza and Bell’s findings were published in Nature Astronomy earlier in July.

“We now know that the disk of the Andromeda galaxy survived this particularly large merger, though we don’t know exactly why. So, this finding upsets a major paradigm in our understanding of galaxy evolution. One thing we can take away is that the disks of galaxies are more resilient than previously thought. We hope that this finding motivates further studies to understand what circumstances lead to the disks of galaxies surviving such large interactions. The next part of my research involves studying the stellar halos and the merger histories of other more distant galaxies, to try and understand which of the galaxy’s properties are caused by merging,” the scientist explained to Firstpost.

Discovering and studying this decimated galaxy will help astronomers understand how disk galaxies like the Milky Way evolve and survive large mergers. “This project was a big risk, but I am glad it paid off. The main thing is that we learned a lot, and we had great fun doing the project,” he said.

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