With the federal government cutting funds for research, scientific organizations are facing a budget crunch. This includes astrophysics and cosmology, where researchers test theories fundamental to our understanding of the Universe. A good example is the search for Dark Matter (DM), which usually consists of smashing protons in particle accelerators to find evidence of this elusive particle. According to a recent study that appeared in the Physical Review Letters, black holes could represent a cheaper, natural alternative.
The study was conducted by Dr. Andrew Mummery of the Rudolf Peierls Centre for Theoretical Physics at the University of Oxford. He was joined by Joseph Silk, a Professor of Physics and Astronomy with the Institut d'Astrophysique de Paris, the William H. Miller III Department of Physics and Astronomy at The Johns Hopkins University, and the Beecroft Institute of Particle Astrophysics and Cosmology at the University of Oxford.
As Mummery and Silk argue, using black holes for scientific research could complement multi-billion-dollar facilities that take decades to construct. The most notable of these is CERN's Large Hadron Collider, the world's largest and most powerful particle accelerator in the world. In these facilities, protons and other subatomic particles are smashed together at velocities approaching the speed of light, producing subtle energy flashes and debris that could reveal previously undiscovered particles.
This includes potential candidate particles for dark matter, which accounts for roughly 85% of all matterUniverseUniverse. In addition, facilities like the LHC have helped to advance the internet and research into cancer therapy and high-performance computing. As Silk explained in a JHU Hub press release:
"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. 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."
A schematic map showing a possible location for the Future Circular Collider. Credit: CERN
Kerr black holes, which are very common in the Universe, have angular momentum, meaning that they spin rapidly on their axes. In fact, the accretion of material onto these black holes causes this momentum to increase. Scientists have also noted that supermassive black holes (SMBHs) at the center of galaxies release tremendous amounts of plasma, likely from their accretion disks and relativistic jets emanating from their poles.
As they argue in their study, gas flows that are iUniverse from a black holes accretion disk can produce a "gravitational particle accelerator" with center of mass energies ranging from tens to hundreds of teraelectronvolts (TeV). For comparison, the LHC is capable of generating energies of up to 13 TeV, while the proposed Future Circular Collider (FCC) - currently in development by CERN - will reportedly be capable of generating 100 TeV. In short, these collision events around SMBHs could produce the same results as supercolliders. Said Silk:
"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. 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."
"Some particles from these collisions go down the throat of the black hole and disappear forever. 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. We figured out how energetic these beams of particles could be: as powerful as you get from a supercollider, or more. It's very hard to say what the limit is, but they certainly are up to the energy of the newest supercollider that we plan to build, so they could definitely give us complementary results."
Artist's impression of a rotating SMBH surrounded by an accretion disk. Credit: ESO/ESA/Hubble/M. Kornmesser/N. Bartmann
While distance is certainly a factor, these particle collisions could be studied using observatories that are currently tracking supernova and other energetic cosmic events - such as neutrino events. Examples include the IceCube Neutrino Observatory at the South Pole or the Kilometer Cube Neutrino Telescope (KM3Net), a next-generation neutrino telescope located beneath the Mediterranean Sea. There's also the Global Neutrino Network (GNN), an international organization that plans to enable closer collaboration among neutrino observatories worldwide.
There have also been proposals to observe the gamma-ray bursts (GRBs) coming from the center of the Milky Way for possible evidence of DM. These investigations could offer a cost-effective means of testing the standard model of cosmology and physics that could complement high-cost research involving supercolliders.
Further Reading: JHU, Physical Review Letters
