New research has cast doubt on the long-held theory that our galaxy, the Milky Way, will collide with its largest neighbour, the Andromeda galaxy, in 4.5 billion years-time.
Scientists used data from NASA’s Hubble and the European Space Agency’s Gaia space telescopes to simulate how the Milky Way, Andromeda and their most massive satellite galaxies could evolve over the next 10 billion years.
They found that there is only a 2% probability that the galaxies will collide in the next 5 billion years, contrary to the previous belief that a collision was a certainty within that timeframe.
In around half of the simulated scenarios, the Milky Way and Andromeda experience at least one close encounter, before losing enough orbital momentum to eventually merge.
In most other cases, the two galaxies pass at such a large distance that they continue to evolve largely unperturbed for a very long time.
If the Milky Way and Andromeda are to collide and merge, the researchers found that it would most likely happen in 7 to 8 billion years’ time, significantly later than previously predicted.
Such a collision would be devastating for both galaxies which would be destroyed, leaving behind a spheroidal pile of stars known as an elliptical galaxy.
There could, however, be cosmic firework: gas will be funnelled to the centre and emit huge amounts of radiation as it falls into a central black hole at the heart of the merger remnant.
Dr Till Sawala of the University of Helsinki led the study and was a Postdoctoral Research Assistant at Durham whilst carrying out the research.
He emphasised, although this new research casts doubt on the previously accepted future of our galaxy, the new conclusions do not imply a mistake in earlier calculations.
Rather, the team were able to use new data and explore a much larger array of possibilities in than ever before.
Meanwhile, uncertainty about the future of the Milky Way and Andromeda may not last.
The research team is already looking ahead to the Gaia space telescope which will soon deliver more precise measurements of some of the most crucial variables within the galaxies, including the transverse motion of Andromeda.
Carlos Frenk, co-author of the research and Professor in our Institute for Computational Cosmology, said: “It is amazing that we are able to simulate the evolution of gigantic collections of stars over billions of years and figure out their ultimate fate.
“This is a testimony to the power of physics allied to the power of large supercomputers.”
The study has been published in the journal Nature Astronomy.
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