Indian astronomers discover cosmic changes when galaxy flies past Milky Way

A new study by Indian astronomers discovered that when a smaller galaxy passes by a much larger galaxy, the latter's structure is severely disrupted. The researchers found that if a smaller galaxy passes close enough to the Milky Way, it can cause spiral arms to emerge in Akashganga. The study was published in the Monthly Notices of the Royal Astronomical Society. For two types of bulges, astronomers explored the influence of small flybys on the bulges, discs, and spiral arms of Milky Way mass galaxies. They discovered that the predominant effect on the discs is thickening, as seen by an increase in the disc scale height to scale radius ratio. According to astronomers, galaxy flybys, which involve the exchange of considerable amounts of mass and energy, are as common as mergers in the low-redshift universe. They are vital for galaxy evolution because they involve the exchange of significant amounts of mass and energy. The astronomers emphasised the importance of their research by stating that the formations fade away with time. 

A galactic flyby occurs on a gigantic scale and refers to a near encounter between two spacecraft, fighter jets, or two objects. Unlike galaxy mergers, where one galaxy merges with another to form a larger one, flyby galaxies approach each other, exert a powerful gravitational pull on each other and then separate on their respective courses. Flybys are significantly more prevalent in the local Universe, according to the research, which was led by Ankit Kumar, a PhD student at the Indian Institute of Astrophysics (IIA). Over billions of years, both mergers and flybys have played a key role in shaping galaxies, according to the study. Using cutting-edge computer models, the research team looked into the gravitational influence of each galaxy on the motion of the stars.

The researchers develop a disc galaxy similar to Milky Way

The research team developed a disc galaxy similar to the Milky Way and used it to replicate flybys of smaller galaxies while tweaking various parameters such as the smaller galaxy's mass, the distance they approach, the type of bulge in the larger galaxy, and so on. The simulations revealed that when a smaller galaxy passes by a big galaxy, it causes spiral arms to emerge in the latter's disc. The researchers also discovered that the gravitational influence's spiral arms grew stronger when the distance between the two galaxies shrank. They observed that the power of spiral arms begins to wane as soon as the smaller galaxy exits the big galaxy's strong gravitational pull.

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