I think that there exist neutronic stars, but do they emit? Do we receive neutron radiation from those stars? If not, are there other sources of fermions?
Sofia,
I know of no evidence for the detection of neutrons in space. There are several reasons why this is not surprising.
Any lone neutron has a short half-life, of the order of minutes, and thus one would need to postulate exceedingly fast-moving neutrons for them to survive the journey from their presumed origin to a detector.
Secondly, I know of no process in a star-like environment that can generate fast moving neutrons.
James,
You are right and thank you very much. My question was naïve and I should have though of this. So, I modified it. Are there maybe, intense sources of other types of fermions?
With many thanks for correcting me,
Sofia
Sofia, your question is not so naive if we consider the high energy neutrons. Despite the short mean life time (t=882 s), the neutron with kinetic energy 2 EeV (2x10^9 GeV), being produced by ultrahigh energy proton (p+p-->n+X) in the galactic central region, has a high chance of escaping from our galaxy due to relativistic time dilation. Moreover, a newborn supernova remnant, being opaque for protons due to strong magnetic field in the shockwave region for about a month, is transparent for neutrons produced by proton interactions in the remnant media. Thus, the very young supernova remnant can be considered as a high energy neutron source along with gamma and neutrino accompaniment. At present, provided that the corresponding relativistic time dilation is enough to reach the Earth, the detection of very high energy neutrons from nearby newborn supernova or ultrahigh energy neutrons produced in the galactic center is impossible due to high cosmic ray proton background flux and an identity of very high energy proton and neutron detector responses at the observation level.
Dear Samvel,
Thanks for your answer. So, I understand from you that we don't have the chance to "see" on the Earth a cosmic source of neutrons.
Best regards,
Sofia
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