In the face of eye-watering costs, long construction times and the Trump administration’s slashing of federal science funding, physicists have proposed a cheaper alternative to the next-generation of particle supercolliders — peering into black holes.
Scientists initially hoped that the elusive particles that make up dark matter would be spat out by high-energy proton collisions inside CERN’s Large Hadron Collider (LHC), yet so far no such detection has been made.
Finding dark matter, therefore, could mean waiting decades until new, higher energy, supercolliders are built.
Or perhaps not, according to one group of researchers. Publishing their findings June 3 in the journal Physical Review Letters, they suggest that the answers we’re looking for could be in violent collisions inside the fast-moving accretion disks that surround enormous black holes.
“One of the great hopes for particle colliders like the Large Hadron Collider is that it will generate dark matter particles, but we haven’t seen any evidence yet,” study co-author Joseph Silk, an astrophysics professor at Johns Hopkins University and the University of Oxford, U.K. said in a statement. “That’s why there are discussions underway to build a much more powerful version, a next-generation supercollider. But as we invest $30 billion and wait 40 years to build this supercollider — nature may provide a glimpse of the future in super massive black holes.”
Particle colliders work by smashing particles into each other at near-light-speeds, creating interactions from which the most fundamental elements of the universe briefly emerge as high-energy debris. It’s from these collisions that the LHC discovered the Higg’s Boson in 2012, the elusive particle that gives all others their mass.
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But despite this discovery and many others (alongside key contributions to the development of the internet, computing and some cancer therapies) the LHC has yet to produce dark matter, possibly because it is incapable of reaching the energies required to produce its particles.
One of the universe’s most mysterious components, dark matter makes up roughly 27% of our cosmos’s missing content. But it doesn’t interact with light, so it has yet to be directly detected. This means that despite countless observations of the ways it shapes our universe, scientists are still unsure of where dark matter comes from, or even what it is.
Seeking a new source of dark matter particles, the researchers behind the new study looked to black holes. Observations by space telescopes have revealed that rapidly spinning black holes can launch massive jets of plasma from the accretion disks of hot matter that surround them.
And according to the researchers’ calculations, these jets could be far more powerful than first thought — enabling particles to collide at similar energy levels as those projected for future supercolliders.
“Some particles from these collisions go down the throat of the black hole and disappear forever,” Silk said. “But because of their energy and momentum, some also come out, and it’s those that come out which are accelerated to unprecedentedly high energies.”
Silk’s team calculated that the energy produced by black hole jets could be “as powerful as you get from a supercollider, or more,” adding that “it’s very hard to say what the limit is.”
To detect the particles zipping from black hole collisions, the researchers propose tracking them with observatories designed to study supernovae, such as the South Pole’s IceCube Neutrino Observatory or the Kilometer Cube Neutrino Telescope.
“If supermassive black holes can generate these particles by high-energy proton collisions, then we might get a signal on Earth, some really high-energy particle passing rapidly through our detectors,” Silk said. “That would be the evidence for a novel particle collider within the most mysterious objects in the universe, attaining energies that would be unattainable in any terrestrial accelerator. We’d see something with a strange signature that conceivably provides evidence for dark matter, which is a bit more of a leap but it’s possible.”
