The newly-discovered darkish dwarf galaxy Antlia 2’s collision with the Milky Means could also be liable for our galaxy’s attribute ripples in its outer disc, in keeping with a examine led by Rochester Institute of Expertise Assistant Professor Sukanya Chakrabarti.
The Antlia 2 dwarf galaxy was found from the second knowledge launch of the European House Company’s Gaia mission, which goals to chart a three-dimensional map of our galaxy. Antlia 2’s present location carefully matches the placement of a dark-matter dominated dwarf galaxy that Chakrabarti predicted in 2009 via a dynamical evaluation. Utilizing the Gaia knowledge, Chakrabarti calculated its previous trajectory and located that Antlia 2 would have crashed into the Milky Means and produced the massive ripples that we see within the outer gasoline disc of our galaxy.
Upcoming extra knowledge releases from Gaia will present additional readability, and Chakrabarti mentioned that she and her crew have made “a hand-on-the-cutting-board kind of prediction of what to expect for the motion of the stars in the Antlia 2 dwarf galaxy in future Gaia data releases.” Chakrabarti mentioned the invention might assist develop strategies to hunt for darkish galaxies and in the end remedy the long-standing puzzle of what darkish matter is.
“We don’t understand what the nature of the dark matter particle is, but if you believe you know how much dark matter there is, then what’s left undetermined is the variation of density with radius,” mentioned Chakrabarti. “If Antlia 2 is the dwarf galaxy we predicted, you know what its orbit had to be. You know it had to come close to the galactic disc. That sets stringent constraints, therefore, on not just on the mass, but also its density profile. That means that ultimately you could use Antlia 2 as a unique laboratory to learn about the nature of dark matter.”
The researchers additionally explored different potential causes for the ripples within the Milky Means’s outer disc, however dominated out the opposite candidates. The Sagittarius dwarf galaxy’s tidal power was inadequate and the Giant and Small Magellanic Clouds are too distant. The proof factors to Antlia 2 because the almost definitely trigger.
Chakrabarti introduced her findings on the 234th assembly of the American Astronomical Society in St. Louis, Mo., on Wednesday, June 12.
Chakrabarti’s work is supported by NASA ATP NNX17AK90G and NSF AAG grant 1517488. Different researchers contributing to the examine included Philip Chang, affiliate professor at College of Wisconsin-Milkwaukee; Adrian Value-Whelan, postdoctoral fellow at Princeton College; Justin Learn, professor at College of Surrey; Leo Blitz, professor at College of California Berkeley; and Lars Hernquist, professor at Harvard College.