Antlia 2, the "galaxy specter" circling the Milky Way, is a dark horse in more than one way. Not only is it so weak that it was only discovered last year but can now be responsible for the curious waves in the hydrogen gas that forms the outer disk of the Milky Way. According to new research, Antlia's current situation is consistent with a clash with the Milky Way hundreds of millions of years ago, which could have produced the turmoil we see today. The document is submitted for publication and is under peer review.
Antlia 2 was a bit of a surprise when he appeared in the second edition of Gaea's mission data last year. It's really close to the Milky Way ̵
But it's incredibly diffuse and weak, and hidden from view from the galactic disk, so he managed to avoid detection.
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This data message also showed more detailed waves in the Milky Way disk. But astronomers knew about the disruptions in this region on the disk for several years to date, even if the data were not as clear as those provided by Gaia.
Based on this earlier information, astrophysicist Sukanya Chakrabartti of Rochester Institute of Technology and his colleagues predicted the existence of dwarfs dominated by dark matter in the exact place where Antlia 2 was discovered for nearly a decade. later.
Using Gaia's new data, the team calculated Antlia 2's past trajectory and conducted a series of simulations. They produced not only the current position of the dwarves but also the waves in the Milky Way disk through a collision less than a billion years ago. Previously, a different team of researchers attributed these interference to the Sagittarius dwarf spheroidal galaxy, another of the Milky Way companions. Chakrabart and her team conducted simulations of this scenario and discovered that the gravity of the Sagittarius galaxy is probably not strong enough to produce the effects observed by Gaia.
"In this way," researchers say in his article, "we claim that Antlia 2 is the likely driver of the major interference observed in the Galaxy's external gas disk."
Previous simulations conducted by the team found by Antlia 2 suggest that much of the dwarf galaxy's material has been absorbed over time by tidal interactions with the Milky Way. If they both collide, this is one of the possible ways to get at least some material. And if they collide, it will allow astronomers to track the history of the dwarves, which can shed light on the dark matter profile. While most of the dark matter has a tendency to gather in galactic centers, the extreme diffusion of Antlia 2 may mean that it is home to a different distribution. Chakrabarti's previous prediction was heavily relied on the presence of dark matter.
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"If Antlia 2 is the dwarf galaxy we predicted, you know what its orbit you know to get closer to the galactic disk, "she said." This places strict limitations, therefore, not only on the table, but also on its density profile. This means you can ultimately use Antlia 2 as a unique lab to learn about the nature of dark matter. "
There is still something else to create waves, but the team has also thought about it. their reconstruction of past events, they predicted the future positions of the stars in Antlia 2.
The next Gaia data message is expected for a year or two, if the data coincide with the team's predictions, it will make a significant contribution to the theory. The study was passed on to The Astrophysical Journal Letters [No and published in ArXiv