Astrophysicists at Durham University’s Institute for Computational Cosmology in the UK and the University of Helsinki in Finland have predicted that a dwarf galaxy called the Large Magellanic Cloud (LMC), which weighs as much as 250 billion suns, will slam into the Milky Way in about two and a half billion years.
Should it happen for real, the cosmic collision will wreak havoc in our galactic neighborhood that could likely send our Solar System tumbling into the infinite void of interstellar space.
The massive impact is also likely to wake up the Milky Way’s hibernating blackhole, which will then begin devouring the surrounding gases and bloat to ten times its original size.
The awakened giant will spit out high-energy radiation in the galactic neighborhood in a dazzling display of cosmic eruptions.
“Barring any disasters, like a major disturbance to the solar system, our descendants, if any, are in for a treat: a spectacular display of cosmic fireworks as the newly awakened supermassive black hole at the center of our galaxy reacts by emitting jets of extremely bright energetic radiation,” said Prof. Carlos Frenk, study co-author and director of the Institute for Computational Cosmology at Durham.
While it may seem like a lot of fuss is being made over something that’s predicted to take place 2.5 billion years from now, “it is a very short time on cosmic timescales,” according to lead author Marius Cautun, a postdoctoral fellow at Durham’s.
The astrophysicists arrived at the scary conclusion after computer simulations of the LMC’s orbital trajectory revealed that the satellite galaxy, one among many orbiting our Milky Way, is headed for an imminent collision with the parent galaxy.
The simulations show that the LMC, which is now 163,000 lightyears away from our own galaxy and careening away from it at 900,000 miles per hour (1.4 million kilometers per hour), will eventually decelerate and reverse its trajectory to come crashing back into the Milky Way.
“The whole of the Milky Way will be shaken and the entire solar system could be ejected into outer space,” said Prof. Frenk.
“If that happens, I don’t see how our descendants, if we have any, will be able to withstand it,” he added.
Before the Durham discovery, astronomers believed that the Milky Way was facing total annihilation in about eight billion years’ time, but from an altogether different galaxy called Andromeda, five times more massive than the Large Magellanic Cloud.
Although the LMC bang is expected to happen much sooner, it may probably push the Milky Way out of harm’s way, thereby saving it from the bigger Andromeda, which is sure to spell our doom should it hit us.
“One of the by-products of the collision with the LMC is it will delay Armageddon,” explained Prof. Frenk.
“It will move the Milky Way a bit and that may buy us a couple of billion years,” he said.
“The LMC is big but it won’t completely destroy our galaxy,” he continued, going on to say that “it’ll produce these amazing fireworks, but it doesn’t have the mass to create a huge disturbance.”
He added: “The collision with Andromeda really will be Armageddon. That really will be the end of the Milky Way as we know it.”
The Milky Way is not a regular spiral galaxy because its inactive black hole is too small in the order of magnitude.
Also, our galaxy’s stellar halo has way too fewer heavy elements compared to regular spiral galaxies and the LMC is unusually large for a satellite galaxy.
However, all that will change when the LMC eventually smashes into the Milky Way.
“Once the LMC gets gobbled up by the Milky Way, our galaxy will become a beautiful, normal spiral,” Frenk said.
“Most of the halo will become stars from the LMC and the black hole will gorge on this sudden unexpected abundance of fuel and it will go berserk,” he added.
Durham University’s Alis Deason, one of the co-authors of the paper says that “many of the apparent ‘unusual’ properties of the Milky Way are temporary,” but “after the collision with the LMC, the Milky Way will look much more typical.”
Owing to the fact that there is way too much space between stars in a galaxy, the collision will most likely spare Earth any major destruction.
“This is not a ‘collision’ in the sense of a car crash,” said Scott Tremaine from the Institute for Advanced Study in New Jersey, who was not involved in the study.
“The effect of a merger with the Cloud on the Sun and Earth would be negligible, except perhaps that the night sky would look more interesting,” Tremaine added.
The paper entitled “The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud” has been published in the journal “Monthly Notices of the Royal Astronomical Society.”