Milky Way collision path mirrored in distant galaxy pair
Dr Sarah Sweet from the School of Mathematics and Physics heads Delegate, a collaboration with the Australian National University's Research School of Astronomy and Astrophysics and others, to assess whether the Milky Way's path is typical in the cosmos. She said the Milky Way will merge with Andromeda and associated dwarf galaxies in about 2.5 billion years, but the survey's targets - NGC5713 and NGC5719 - are already 3 billion years further along.
Sweet explained the galaxies appear to orbit each other with nearby dwarf satellites moving in coherent planes, rather than being scattered in random clouds. Without the merger, such ordered structures might not form. She said the finding could reveal how the Milky Way's satellite system developed and provide new insight into galaxy evolution, dark matter, and cosmic structure.
"This may offer our clearest look yet at how structures like the Milky Way's satellite system form, and how they will evolve," she said. "We are part of a much larger cosmic story, one that unfolds over billions of years, involving dances of galaxies and the shaping of the universe itself."
ANU Professor Helmut Jerjen, who leads related research papers, said the team is comparing the Milky Way and Andromeda to other galaxy pairs to see if our system is representative. He noted current observations, such as the placement of dwarf galaxies in satellite planes, challenge existing cosmological simulations.
"These observations suggest we need to overhaul current simulations," Jerjen said. "Will the Milky Way begin its own dance with Andromeda with the smaller dwarf galaxies rotating around them? That's what we want to find out."
Research Report:The coherent satellite velocity field around the interacting spiral galaxy pair NGC5713/19: signature of two galaxy groups merging
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