Astronomers Detected Signs of Milky Way Colliding With Another Galaxy

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Recently astronomers detected signs of Milky Way colliding with another galaxy. Antlia 2, the “ghost of a galaxy” that orbits the Milky Way, is more than one dark horse. It is so faint that it was only found last year. It can now be accountable for curious ripples in the hydrogen gas that make up the exterior disc of the Milky Way.

Antlia 2’s present situation, according to fresh studies, is compatible with collision hundreds of millions of years ago with the Milky Way that could have caused the disturbances we see today. The paper was presented for publishing and is being peer-reviewed.

Antlia 2 was a bit surprised when it appeared in last year’s second release of information from the Gaia mission. It’s really near to the Milky Way. One of our satellite galaxies and about the size of the Large Magellanic Cloud it’s totally huge.

But the galactic disc is extremely diffuse and faint and hidden from perspective, so it managed to escape detection.

That release of information also reveals ripples in the Milky Way’s disc in more detail. But astronomers had known by that stage for several years about disturbances in that region of the disc. Even though the information was not as evident as Gaia’s.

It was based on this previous data that the Rochester Institute of Technology’s astrophysicist Sukanya Chakrabarti and peers anticipated the presence of a dark matter. Dominated dwarf galaxy approximately a century later at the precise place of Antlia 2 in 2009.

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The team calculated the previous trajectory of Antlia 2 using the fresh Gaia information and conducted a sequence of simulations. These generated not only the present position of the dwarf galaxy but the ripples of a crash less than a billion years ago in the Milky Way’s disc.

antlia collision - Astronomers Detected Signs of Milky Way Colliding With Another Galaxy
Astronomers Detected Signs of Milky Way Colliding With Another Galaxy. Simulation of the collision: The gas distribution is on the left, stars on the right. (RIT)

Previously, these disturbances were ascribed to an interaction with the Sagittarius Dwarf Spheroidal Galaxy, another satellite of the Milky Way, by a distinct group of scientists.

Chakrabarti and her team also conducted this scenario simulations and discovered that the gravity of the Sagittarius galaxy is likely not powerful enough to generate Gaia’s observed impacts.

“So,” the scientists wrote in their paper, “we claim that Antlia 2 is the probable driver of the big disturbances found in the Galaxy’s exterior gas disc.”

Previous simulations run by the team that discovered Antlia 2 suggested that through tidal interactions with the Milky Way, much of the material of the dwarf galaxy has been absorbed over time. If the two collided, at least some material was transmitted in one possible manner.

And if the two collided, this would allow astronomers to trace the history of the dwarf galaxy. Which might shed some light on its profile of dark matter. While dark matter tends to clump together in galactic centers most of the moment. The exceptional diffuseness of Antlia 2 might imply that it is home to another distribution.

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And the earlier forecast of Chakrabarti depended strongly on the existence of dark matter. “If Antlia 2 is the dwarf galaxy we anticipated, you understand what it had to be in its orbit. You know it had to come close to the galactic disc,” she said.

“That, therefore, lays stringent limitations not only on the mass but also on its density profile. Meaning that you could eventually use Antlia 2 as a distinctive laboratory to learn about the nature of dark matter.”

There’s still a chance that the ripples were generated by something else, but the team also thought about that. They anticipated the future positions of the stars in Antlia 2 based on their reconstruction of previous occurrences.

The next release of Gaia information is due in one or two years. If the information matches the projections of the team, the theory will be given important weight. The study was presented and published on arXiv to The Astrophysical Journal Letters.


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