Zoom / When neutrinos interact with particles in clear Antarctic ice, they produce secondary particles that leave a trail of blue light as they travel through the IceCube detector.
Nicole R. Fuller, IceCube/NSF
This low rate of reaction makes neutrinos It is very difficult to detect, but because it is so light, it can escape unimpeded (and thus largely unaltered) by colliding with other matter particles. This means they might provide valuable clues to astronomers regarding distant systems, bolstered by what can be learned with telescopes across the electromagnetic spectrum, as well as gravitational waves. Together, these various sources of information have been called “Multiple Messenger” astronomy.
Most neutrino hunters bury their experiments deep in the earth, and it is better to cancel out loud interference from other sources. In the case of the IceCube, the collaboration features arrays of basketball-sized optical sensors buried deep in Antarctica’s ice. On those rare occasions when a transient neutrino interacts with the nucleus of an atom in the ice, the collision produces charged particles that emit ultraviolet light and blue photons. These are captured by sensors.
So IceCube is well positioned to help scientists advance their knowledge of the origin of high-energy cosmic rays. Like Natalie Wolcoffer convincingly Explained in Quanta In 2021:
A cosmic ray is just an atomic nucleus – a proton or group of protons and neutrons. However, rare cosmic rays known as “ultra-energy cosmic rays” have just as much energy as professionally served tennis balls. They are millions of times more energetic than the protons orbiting around the circular tunnel of the Large Hadron Collider in Europe at 99.9999991% of the speed of light. In fact, the most energetic cosmic ray ever discovered, dubbed a “oh my god” particle, hit the sky in 1991 at 99.9999999999999999999951 per cent of the speed of light, giving it the energy of a bowling ball that fell from shoulder height to toe height .
But where do such powerful cosmic rays originate? One of the strong possibilities Active Galactic Nuclei (AGNs), found in the middle of some galaxies. Its energy originates from the supermassive black holes at the center of the galaxy, and/or from the rotation of the black hole.
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