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A preon star[1] is a theoretical type of compact star made of preons, which are "point-like" particles conceived to be subcomponents of quarks and leptons.[2] Their existence was first theorized in 2005 by Fredrik Sandin and Johan Hansson, both from the Luleå University of Technology, Sweden.[3] The theory behind them was that the sub-subatomic particles would have come before subatomic particles, which came before particles, and that the original stars were made of these sub-subatomic particles, with most gradually becoming made of sub-particles, and then particles. However, the theory postulates that it is possible for some stars made of the sub-subatomic particles to remain.[4] It is believed that they may also form out of massive stars that collapse too unstably to become neutron stars, but not enough to become black holes.[5]

Properties
Orders of magnitude

The mass of a preon star is predicted to be[5]

\( {\displaystyle M\sim 2\times 10^{24}kg\left({\frac {TeV}{\Lambda }}\right)^{\tfrac {3}{2}},} \)

where

Λ is the top quark compositeness energy scale.
TeV is the number of tera-electron volts.

The radius of a preon star is estimated to be[5]

\( {\displaystyle R\sim 3\times 10^{-3}m\left({\frac {TeV}{\Lambda }}\right)^{\tfrac {3}{2}},} \)

The maximum mass of a preon star is predicted to be \( {\displaystyle \sim 10^{2}M_{\oplus }} \).[5] where \( M_\oplus \) is the mass of the earth.

The maximum radius of a preon star is predicted to be \( {\displaystyle R\sim 1m} \) .[5]

The average density of a preon star is predicted to be \( {\displaystyle \sim 10^{23}g/cm^{3}} \); however, the density of the center is predicted to be greater.[5]
Comparison with other stellar objects

If they exist, the eigenmode frequency for radial oscillations of a preon star will be 106 greater than that of a neutron star. As the radius will be roughly 105 smaller than the radius of a neutron star, if sound travels through preons at the same speed it does neutrons, then the frequency will be increased by 105, giving GHz frequencies. If sound travels faster in preons than it does neutrons, the frequency cannot exceed \( {\displaystyle \sim 10^{8}ms^{-1}/0.1m\eqsim 1GHz} \) even if the speed of light is approached.[5]

The existence of preons could explain ultra-high-energy cosmic rays, as no known type of star or object can project cosmic rays with as much energy as they have, going up to 1021 eV. The possibility of a massive star collapsing and, being too unstable to collapse only to a pulsar star, collapsing all the way to a pulsar preon star with a radius of a meter and a mass of 100 earths, would allow pulsar yields of up to \( {\displaystyle \sim 10^{34}V/m} \) , which would be more than enough for an ultra-high-energy cosmic ray. It is believed that any preon star under the maximum mass will be stable.[5]

If preons exist, they, and by extension preon stars, will not perform nucleosynthesis. Nor will such stars emit Hawking radiation. It is believed that a preon star will have a large magnetic field, and rapid rotation.[5]
Theory and evidence

One of the reasons that the theory of preon stars has so few backers, is that the existence of preons would contradict not only the theory of the Higgs boson, but also the Standard Model of Physics.[6] As the Higgs boson was tentatively confirmed by CERN, the prevailing theory at present is that preons' existence is impossible.[7] The two methods that are used to try to find preons – gravitational femtolensing and searching for gravitational waves – have so far yielded nothing.[3]

Preons, if they exist, will be impossible to create even with the Large Hadron Collider, as it would require conditions similar to those of the Big Bang.[8]
References

Hansson, J; Sandin, F (2005). "Preon stars: a new class of cosmic compact objects". Physics Letters B. 616 (1–2): 1–7. arXiv:astro-ph/0410417. Bibcode:2005PhLB..616....1H. doi:10.1016/j.physletb.2005.04.034. S2CID 119063004.
D'Souza, I.A.; Kalman, C.S. (1992). Preons: Models of Leptons, Quarks and Gauge Bosons as Composite Objects. World Scientific. ISBN 978-981-02-1019-9.
Dorminey, Bruce (20 November 2007). "Focus: Nuggets of New Physics". Physics. Retrieved 19 January 2017.
Ball, Philip (30 November 2007). "Splitting the quark". Nature. doi:10.1038/news.2007.292. Retrieved 20 January 2017.
Sandin, Fredrik (2007). "1" (PDF). Exotic Phases of Matter in Compact Stars (Thesis). Luleå University of Technology. OCLC 185216905. Retrieved 20 January 2017.
Wilkins, Alasdair. "Stars so weird that they make black holes look boring". io9. Retrieved 19 January 2017.
O'Luanaigh, C. (14 March 2013). "New results indicate that new particle is a Higgs boson". CERN. Retrieved 19 January 2017.

"The Odd Case of Preon Stars". Great Discoveries Channel. The Daily Galaxy. Retrieved 20 January 2017.

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