science

Updated: Jul 30, 2018 07:05 IST

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

Speaking the Hindustan Times from the University of Michigan USA, where he made the discovery, Fr Richard D’Souza said 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 said.

Part of the problem lay in the fact that a galaxy like Andromeda was expected to have consumed hundreds of its smaller companions. The researchers thought this would make it difficult to learn about any single one of them.

More importantly this discovery and its method will now pave the way for the discovery of other galaxies that have been cannibalized by other larger galaxies.

“We knew we could recover some information from the existing data, but it also gave us a way forward to solving similar problems with other galaxies,” he said.

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.

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

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. Using computer models, D’Souza and Bell were able to piece together this evidence, revealing this long-lost sibling. Their findings were published in Nature Astronomy earlier this month.

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.

Their discovery could alter the traditional understanding of how galaxies evolve. The duo realised that the Andromeda’s disk survived an impact with a massive galaxy, which would question the common wisdom that such large interactions would destroy disks and form an elliptical galaxy.

The timing of the merger may also explain the thickening of the disk of the Andromeda galaxy as well as a burst of star formation two billion years ago, a finding which was independently reached by French researchers earlier this year.