{"id":359947,"date":"2023-11-23T14:11:54","date_gmt":"2023-11-23T19:11:54","guid":{"rendered":"https:\/\/platohealth.ai\/telescope-array-detects-second-highest-energy-cosmic-ray-ever\/"},"modified":"2023-11-26T02:31:35","modified_gmt":"2023-11-26T07:31:35","slug":"telescope-array-detects-second-highest-energy-cosmic-ray-ever","status":"publish","type":"post","link":"https:\/\/platohealth.ai\/telescope-array-detects-second-highest-energy-cosmic-ray-ever\/","title":{"rendered":"Telescope Array detects second highest-energy cosmic ray ever","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"
<\/div>\n

In 1991, the University of Utah Fly\u2019s Eye experiment detected the highest-energy cosmic ray ever observed. Later dubbed the Oh-My-God particle, the cosmic ray\u2019s energy shocked astrophysicists. Nothing in our galaxy had the power to produce it, and the particle had more energy than was theoretically possible for cosmic rays traveling to Earth from other galaxies. Simply put, the particle should not exist.\u00a0<\/p>\n

Credit: Osaka Metropolitan University\/L-INSIGHT, Kyoto University\/Ryuunosuke Takeshige<\/p>\n

\n

In 1991, the University of Utah Fly\u2019s Eye experiment detected the highest-energy cosmic ray ever observed. Later dubbed the Oh-My-God particle, the cosmic ray\u2019s energy shocked astrophysicists. Nothing in our galaxy had the power to produce it, and the particle had more energy than was theoretically possible for cosmic rays traveling to Earth from other galaxies. Simply put, the particle should not exist.\u00a0<\/p>\n

The Telescope Array has since observed more than 30 ultra-high-energy cosmic rays, though none approaching the Oh-My-God-level energy. No observations have yet revealed their origin or how they are able to travel to the Earth.<\/p>\n

On May 27, 2021, the Telescope Array experiment detected the second-highest extreme-energy cosmic ray. At 2.4 x 1020<\/sup>eV, the energy of this single subatomic particle is equivalent to dropping a brick on your toe from waist height. Led by the University of Utah (the U) and the University of Tokyo, the Telescope Array consists of 507 surface detector stations arranged in a square grid that covers 700 km2\u00a0<\/sup>(~270 miles2<\/sup>) outside of Delta, Utah in the state\u2019s West Desert. The event triggered 23 detectors at the north-west region of the Telescope Array, splashing across 48 km2<\/sup>\u00a0(18.5 mi2<\/sup>). Its arrival direction appeared to be from the Local Void, an empty area of space bordering the Milky Way galaxy.\u00a0<\/p>\n

\u201cThe particles are so high energy, they shouldn\u2019t be affected by galactic and extra-galactic magnetic fields. You should be able to point to where they come from in the sky,\u201d said John Matthews, Telescope Array co-spokesperson at the U and co-author of the study. \u201cBut in the case of the Oh-My-God particle and this new particle, you trace its trajectory to its source and there\u2019s nothing high energy enough to have produced it. That\u2019s the mystery of this\u2014what the heck is going on?\u201d<\/p>\n

In their observation that published on Nov. 24, 2023, in the journal Science<\/em>, an international collaboration of researchers describe the ultra-high-energy cosmic ray, evaluate its characteristics, and conclude that the rare phenomena might follow particle physics unknown to science. The researchers named it the Amaterasu particle after the sun goddess in Japanese mythology. The Oh-My-God and the Amaterasu particles were detected using different observation techniques, confirming that while rare, these ultra-high energy events are real.<\/p>\n

\u201cThese events seem like they\u2019re coming from completely different places in the sky. It\u2019s not like there\u2019s one mysterious source,\u201d said\u00a0John Belz, professor at the U and co-author of the study. \u201cIt could be defects in the structure of spacetime, colliding cosmic strings. I mean, I\u2019m just spit-balling crazy ideas that people are coming up with because there\u2019s not a conventional explanation.\u201d<\/p>\n

Natural particle accelerators<\/strong><\/p>\n

Cosmic rays are echoes of violent celestial events that have stripped matter to its subatomic structures and hurled it through universe at nearly the speed of light. Essentially cosmic rays are charged particles with a wide range of energies consisting of positive protons, negative electrons, or entire atomic nuclei that travel through space and rain down onto Earth nearly constantly.\u00a0<\/p>\n

Cosmic rays hit Earth\u2019s upper atmosphere and blasts apart the nucleus of oxygen and nitrogen gas, generating many secondary particles. These travel a short distance in the atmosphere and repeat the process, building a shower of billions of secondary particles that scatter to the surface. The footprint of this secondary shower is massive and requires that detectors cover an area as large as the Telescope Array. The surface detectors utilize a suite of instrumentation that gives researchers information about each cosmic ray; the timing of the signal shows its trajectory and the amount of charged particles hitting each detector reveals the primary particle\u2019s energy.\u00a0<\/p>\n

Because particles have a charge, their flight path resembles a ball in a pinball machine as they zigzag against the electromagnetic fields through the cosmic microwave background. It\u2019s nearly impossible to trace the trajectory of most cosmic rays, which lie on the low- to middle-end of the energy spectrum. Even high-energy cosmic rays are distorted by the microwave background. Particles with Oh-My-God and\u00a0Amaterasu\u00a0<\/em>energy\u00a0blast through intergalactic space relatively unbent. Only the most powerful of celestial events can produce them.\u00a0\u00a0<\/p>\n

\u201cThings that people think of as energetic, like supernova, are nowhere near energetic enough for this. You need huge amounts of energy, really high magnetic fields to confine the particle while it gets accelerated,\u201d said Matthews.<\/p>\n

Ultra-high-energy cosmic rays must exceed 5 x 1019<\/sup>\u00a0eV. This means that a single subatomic particle carries the same kinetic energy as a major league pitcher\u2019s fast ball and has tens of millions of times more energy than any human-made particle accelerator can achieve. Astrophysicists calculated this theoretical limit, known as\u00a0the\u00a0Greisen\u2013Zatsepin\u2013Kuzmin (GZK) cutoff, as the maximum energy a proton can hold traveling over long distances before the effect of interactions of the microwave background radiation take their energy.\u00a0Known source\u00a0candidates, such as active galactic nuclei or black holes with accretion disks emitting particle jets, tend to be more than 160 million light years away from Earth.\u00a0The new particle\u2019s\u00a02.4 x 1020<\/sup>\u00a0eV\u00a0and the Oh-My-God particle\u2019s 3.2 x\u00a01020<\/sup>\u00a0eV easily surpass the cutoff.<\/p>\n

Researchers also analyze cosmic ray composition for clues of its origins. A heavier particle, like iron nuclei, are heavier, have more charge and are more susceptible to bending in a magnetic field than a lighter particle made of protons from a hydrogen atom.\u00a0The new particle is likely a proton.\u00a0Particle physics dictates that a cosmic ray with energy beyond the GZK cutoff is too powerful for the microwave background to distort its path, but back tracing its trajectory points towards empty space.<\/p>\n

\u201cMaybe\u00a0magnetic fields are stronger than we thought, but that disagrees with other observations that show they\u2019re not strong enough to produce significant curvature at these ten-to-the-twentieth electron volt energies,\u201d said Belz. \u201cIt\u2019s a real mystery.\u201d<\/p>\n

Expanding the footprint<\/strong><\/p>\n

The\u00a0Telescope Array\u00a0is uniquely positioned to detect ultra-high-energy cosmic rays.\u00a0It sits at about 1,200 m (4,000 ft), the elevation sweet-spot that allows secondary particles maximum development, but before they start to decay. Its location in Utah\u2019s West Desert provides ideal atmospheric conditions in two ways: the dry air is crucial because humidity will absorb the ultraviolet light necessary for detection; and the region\u2019s dark skies are essential, as light pollution will create too much noise and obscure the cosmic rays.<\/p>\n

Astrophysicists are still baffled by the mysterious phenomena. The\u00a0Telescope Array is in the middle of an expansion that that they hope will help crack the case. Once completed, 500 new scintillator detectors will expand the Telescope Array will sample cosmic ray-induced particle showers across 2,900 km2\u00a0<\/sup>\u00a0(1,100 mi2\u00a0<\/sup>), an area nearly the size of Rhode Island. The larger footprint will hopefully capture more events that will shed light on what\u2019s going on.<\/p>\n

\n
\n
\n
\n
\n

Journal<\/h4>\n

Science<\/p>\n<\/p><\/div>\n

\n

DOI<\/h4>\n

10.1126\/science.abo5095 <\/i><\/p>\n<\/p><\/div>\n

\n

Method of Research<\/h4>\n

Experimental study<\/p>\n<\/p><\/div>\n

\n

Subject of Research<\/h4>\n

Not applicable<\/p>\n<\/p><\/div>\n

\n

Article Title<\/h4>\n

An extremely energetic cosmic ray observed by a surface detector array<\/p>\n<\/p><\/div>\n

\n

Article Publication Date<\/h4>\n

23-Nov-2023<\/p>\n<\/p><\/div>\n<\/div>\n<\/div>\n<\/div>\n