Oh-My-God particle

The Oh-My-God particle was an

It is not known what kind of particle it was, but most cosmic rays are protons. If ${\displaystyle m_{\mathrm {p} }}$ is the

${\displaystyle E_{\mathrm {K} }}$

${\textstyle {\sqrt {1-[m_{\mathrm {p} }c^{2}/(E_{\mathrm {K} }+m_{\mathrm {p} }c^{2})]^{2}}}}$

${\displaystyle m_{\mathrm {p} }c^{2}}$

Collision energy

The energy of the particle was some 40 million times that of the highest-energy protons that have been produced in any terrestrial particle accelerator. However, only a small fraction of this energy was available for its interaction with a nucleus in the Earth's atmosphere, with most of the energy remaining in the form of kinetic energy of the center of mass of the products of the interaction. If ${\displaystyle m_{\mathrm {t} }}$ is the mass of the "target" nucleus, the energy available for such a collision is^[5]

$${\displaystyle {\sqrt {2E_{\mathrm {K} }m_{\mathrm {t} }c^{2}+(m_{\mathrm {p} }+m_{\mathrm {t} })^{2}c^{4}}}-(m_{\mathrm {p} }+m_{\mathrm {t} })c^{2}}$$

which for large ${\displaystyle E_{\mathrm {K} }}$ is approximately

$${\displaystyle {\sqrt {2E_{\mathrm {K} }m_{\mathrm {t} }c^{2}}}.}$$

For the Oh-My-God particle hitting a nitrogen nucleus, this gives 2900 TeV, which is roughly 200 times higher than the highest collision energy of the Large Hadron Collider, in which two high-energy particles going opposite directions collide.^[6][7] In the center-of-mass frame of reference (which moved at almost the speed of light in our frame of reference), the products of the collision would therefore have had around 2900 TeV of energy, enough to transform the nucleus into many particles, moving apart at almost the speed of light even in this center-of-mass frame of reference. As with other cosmic rays, this generated a cascade of relativistic particles as the particles interacted with other nuclei.

Comparisons

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The Oh-My-God particle's energy was estimated as (3.2±0.9)×10²⁰ 

The Oh-My-God particle had 10²⁰ (100 

Since the first observation, hundreds of similar events (energy 5.7×10¹⁹ eV or greater) have been recorded, confirming the phenomenon.[9]^[10] These ultra-high-energy cosmic ray particles are very rare; the energy of most cosmic ray particles is between 10⁷ eV and 10¹⁰ eV.

More recent studies using the Telescope Array Project have suggested a source of the particles within a 20 degree radius "warm spot" in the direction of the constellation Ursa Major.^[3][10][11]

The Amaterasu particle, named after the sun goddess in Japanese mythology, was detected in 2021 and later identified in 2023, using the Telescope Array observatory in Utah, United States. It had an energy exceeding 240 exa-electron volts (2.4×10²⁰ eV).^[12] This particle appears to have emerged from the Local Void, an empty area of space bordering the Milky Way galaxy.^[13] It contained an amount of energy comparable to dropping a brick from the height of the waist. No promising astronomical object matching the direction from which the cosmic ray arrived has been identified.^[14]

See also

• Greisen–Zatsepin–Kuzmin limit – Theoretical upper limit on the energy of cosmic ray protons
• Ursa Major Cluster – Galaxy cluster of the Virgo Supercluster
• HZE ion – High-energy, heavy ions of cosmic origin
• Solar energetic particles – High-energy particles from the Sun
• Amaterasu particle (2021) – 240 Eev

References