| Jun 06, 2024 |
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(Nanowerk Information) Rensselaer Polytechnic Institute’s Heidi Jo Newberg, Ph.D., professor of astronomy; Tom Donlon, Ph.D., a visiting researcher at Rensselaer and a postdoctoral researcher on the College of Alabama; and their staff have just lately printed analysis (Month-to-month Notices of the Royal Astronomical Society, “The debris of the ‘last major merger’ is dynamically young”) that reveals a stunning discovery in regards to the historical past of our universe: the Milky Method Galaxy’s final main collision occurred billions of years later than beforehand thought.
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The invention was made doable by the European Area Company’s Gaia spacecraft, which is mapping greater than a billion stars all through the Milky Method and past, monitoring their movement, luminosity, temperature, and composition. Newberg, a famend astrophysicist and Milky Method professional, and Donlon centered on the so-called “wrinkles” in our galaxy, that are shaped when different galaxies collide with the Milky Method.
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| On the left the halo seems messy and ‘wrinkly’, an indication {that a} merger has occurred comparatively just lately. On the precise it seems easy and uniform, an indication {that a} merger has as a substitute occurred within the historical previous. (Picture: Halo stars: ESA/Gaia/DPAC, T Donlon et al. 2024; Background Milky Method and Magellanic Clouds: Stefan Payne-Wardenaar; CC BY-SA 3.0 IGO)
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“We get wrinklier as we age, but our work reveals that the opposite is true for the Milky Way. It’s a sort of cosmic Benjamin Button, getting less wrinkly over time,” mentioned Donlon, lead writer of the brand new Gaia research, which additionally served as his doctoral thesis at Rensselaer. “By looking at how these wrinkles dissipate over time, we can trace when the Milky Way experienced its last big crash – and it turns out this happened billions of years later than we thought.”
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By evaluating their observations of the wrinkles with cosmological simulations, the staff was capable of decide that our final important collision with one other galaxy didn’t, actually, happen between eight and 11 billion years in the past, as beforehand believed.
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“For the wrinkles of stars to be as obvious as they appear in Gaia data, they must have joined us no less than three billion years ago – at least five billion years later than was previously thought,” mentioned Newberg, Donlon’s thesis adviser at Rensselaer. “New wrinkles of stars form each time the stars swing back and forth through the center of the Milky Way. If they’d joined us eight billion years ago, there would be so many wrinkles right next to each other that we would no longer see them as separate features.”
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The collision is believed to have resulted in a lot of stars with uncommon orbits. Beforehand, scientists dated it at between eight and 11 billion years in the past in a collision referred to as the Gaia-Sausage-Enceladus (GSE) merger. Reasonably, Newberg and Donlon’s findings point out that the celebrities could have resulted from the Virgo Radial Merger, which crashed by way of the middle of the Milky Method lower than three billion years in the past.
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“Gaia is a hugely productive mission that’s transforming our view of the cosmos,” says Timo Prusti, Ph.D., Mission Scientist for Gaia on the European Area Company. “Results like this are made possible due to incredible teamwork and collaboration between a huge number of scientists and engineers across Europe and beyond.”
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“Through this study, Doctors Newberg and Donlon have made a startling discovery about the history of the Milky Way galaxy,” mentioned Curt Breneman, Ph.D., dean of the College of Science. “Gaia data is offering unprecedented opportunities to better understand our universe, and I am thrilled that Rensselaer researchers were able to harness the power of this incredibly detailed new data.”
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