Ultra High Energy Cosmic Rays from Axion Stars

Abstract

We propose a model in which ultra high energy cosmic rays are produced by collisions between neutron stars and axion stars. The acceleration of such a cosmic ray is made by the electric field, $\sim 10^{15}(B/10^{12}G)eV{cm}^{-1}$, which is induced in an axion star by the strong magnetic field $B>10^{12}$ G of a neutron star. As we have shown previously, similar collisions generate gamma ray bursts when the magnetic field is much smaller, e.g. $\sim 10^{10}$ G. If we assume that the axion mass is $\sim 10^{-9}$ eV, we can explain huge energies of the gamma ray bursts $\sim 10^{54}$ erg as well as the ultra high energies of the cosmic rays $\sim 10^{20}$ eV. In addition, it turns out that these axion stars are plausible candidates for MACHOs. We point out a possibility of observing monochromatic radiations emitted from the axion stars.

A corrected numerical result on page 7

References in corpus (6)

• Extension of the Cosmic-Ray Energy Spectrum Beyond the Predicted Greisen-Zatsepin-Kuz'min Cutoff
• Probing the Cosmic Star Formation History by Brightness Distribution of Gamma-Ray Bursts
• Axionic Boson Stars in Magnetized Conducting Media
• A Possible Origin of Gamma Ray Bursts and Axionic Boson Stars
• Radiations from Oscillating Axionic Boson Stars in an External Magnetic Field
• Energy Dissipation of Axionic Boson Stars in Magnetized Conducting Media

Cited by in corpus (6)

• TOPICAL REVIEW: General relativistic boson stars
• Self-gravitating system made of axions
• Axion Stars and Fast Radio Bursts
• Can the dark matter halo be a collisionless ensemble of axion stars?
• Low mode approximation in the axion magnetohydrodynamics
• Electric and magnetic axion quark nuggets, their stability and their detection