There could be a 90 percent chance that in the next decade, astronomers will spot a deep space explosion that confirms several long-standing theories about black holes – and which releases a complete collection of every particle in existence, known and unknown.
That's according to a new study from physicists at the University of Massachusetts Amherst (UMass Amherst), which proposes that these explosions mark the death of tiny black holes left over from the dawn of the Universe.
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These events were long thought to be incredibly rare, with potentially observable explosions occurring every 100,000 years or so. But the new analysis suggests they're far more common, with a potentially visible explosion popping off every 10 years on average.
When they do, our current technology should be capable of detecting them. Finding one would be a massive boon to astrophysics for several reasons: It would confirm for the first time the existence of this type of black hole, as well as identify the mechanism by which all black holes die.
Even more exciting, such an explosion should release every kind of fundamental particle that exists. That includes all the ones we know about, like boring old electrons and neutrons, but also our 'known unknowns' – the stuff we suspect exists but haven't found yet, like dark matter.
By far the most intriguing thing would be our 'unknown unknowns' – the particles we never even dreamed of.
"We would also get a definitive record of every particle that makes up everything in the Universe," says Joaquim Iguaz Juan, an astrophysicist at UMass Amherst. "It would completely revolutionize physics and help us rewrite the history of the Universe."
The concept of these explosions was first proposed by physicist Stephen Hawking back in 1974. Although black holes have a reputation for slurping up everything that gets too close, Hawking calculated that due to quantum effects, they should actually emit particles too.
This phenomenon, known as " Hawking radiation", would reduce the black holes' mass over time, until they evaporate completely. This radiation is too faint to detect, but in the final death throes it would ramp up into a supernova-like explosion – and this outburst would be detectable.
This process would happen very slowly, so the deaths of stellar mass black holes would be in the very distant future. Supermassive black holes would live even longer. But there could be another, much smaller class of black hole, with shorter lives.
Primordial black holes (PBHs) are thought to have masses on the scale of asteroids, rather than Suns. They're hypothesized to have formed in the first few moments after the Big Bang, hence the 'primordial' moniker.
"The lighter a black hole is, the hotter it should be and the more particles it will emit. As PBHs evaporate, they become ever lighter, and so hotter, emitting even more radiation in a runaway process until explosion," explains Andrea Thamm, physicist at UMass Amherst.
Under Standard Model physics, the age and mass of PBHs suggests most of them should have already evaporated by now. But the team simulated what would happen with a few plausible tweaks to the model.
It includes a hypothetical, heavier version of an electron, which the researchers call a "dark electron". This could provide PBHs with a form of electric charge, which known black holes lack. These changes, the study found, would pause their Hawking radiation for a while and delay the cosmic Grim Reaper's visit, meaning we might not have missed the fireworks after all.
"We show that if a primordial black hole is formed with a small dark electric charge, then the toy model predicts that it should be temporarily stabilized before finally exploding," says Michael Baker, physicist at UMass Amherst.
The team calculates that if their models are correct, one of these explosions should kick off within view of our current gamma ray observatories once every 10 years or so. Seeing one would confirm the existence of PBHs, provide the first direct evidence of Hawking radiation, and give us a full sampler box of all fundamental particles the Universe has to offer.
The research was published in the journal Physical Review Letters.