Supermassive black holes might mean the end of the Milky Way

Contributed by
Jan 22, 2017

Supermassive black holes could be the catalyst in a future collision between the Milky Way and Andromeda, a crash so epic that the two galaxies are expected to merge into one blazing fireworks explosion of energy and star stuff.

Is this science or sensationalism?

Astrophysicist Hai Fu of the University of Iowa believes that our galaxy is doomed to an inevitable head-on collision with Andromeda — we just don't realize it. Galactic merging is a phenomenon as ancient as the universe, and Fu believes that the missing link needed to demystify something that sounds like an ominous headline to a pseudo-science Nostradamus Predicts tabloid is the close observation of supermassive black holes. These dead stars could hold the secrets to what will really happen in the unfathomably far future.

"To the human perspective, our galaxy doesn't appear to be changing," says Fu, "but in the history of the universe, it's changing all the time."

Supermassive black holes are as monstrous as a billion suns (just try conjure a mental image of that when the sun is already several hundred thousand times more massive than Earth). Celestial bodies that immense, even if they are zombie stars, have an equally strong gravitational influence on everything surrounding them. Most of them also reside at the center of a galaxy. Galaxies coming within uncomfortably close proximity of one another would mean that the intense tidal forces exerted by these vast black holes would keep warping and twisting the Milky Way and Andromeda for hundreds of millions of years until they coalesced into one glowing spectacle.

Fu's studies center on the late stages of merging galaxies, when such close proximity results in the onslaught of pulsating energy from tidal forces that will eventually mean their doom. He plans to study a night sky segment of astronomical proportions to find the elusive accreting black holes that could be catalysts for other potential galactic mergers. The size of not just the black hole but the galaxy itself matters when it comes down to who consumes who. Galaxies tend to go cannibalistic when approaching a smaller version of themselves. It is theorized that larger seas of stars devour smaller ones, in which case their black holes will stalk and orbit each other until the immense pull of gravity merges them. It is Andromeda that will bare teeth since it is twice the diameter of the Milky Way and teeming with over a trillion stars (which dwarfs our 200-400 billion), creeping towards us at 200 kilometers per second. Meaning, it will eventually consume our galaxy in this scientifically theorized version of space horror.

While black holes, even supermassive black holes, aren't always in accretion mode, finding pairs of distant galaxies with ones that are is the breakthrough Fu is searching for via the radio waves they emit. The Very Large Array, a National Science Foundation facility operated by the National Radio Astronomy observatory, will produce maps of these radio emissions for further study. Fu and his colleagues have received an NSF grant to study this phenomenon as well as build a virtual reality demonstration to illuminate the influence of gravity in space beyond potential star-mageddons.

So will the people of Earth (if we even exist 4 billion years from now) experience a real-life disaster movie playing out before them as worlds collide? Things transpire so slowly on a galactic scale that the merger is unlikely to affect Earth and its inhabitants much at all, unless another star system ventures too close ... but the idea could always crash the box office.