Remarks on astrophysical origin of the knee in the cosmic ray spectrum

Abstract

All astrophysical explanations of the knee in cosmic ray spectrum accept the hypothesis of its existence a priori without any doubt. But, there exist experimental evidences against this hypothesis. Experimental data on the knee in various secondary cosmic ray components obtained by KASCADE array as well as by many other arrays reveal the existence of the knee (∆γ ≈ 0.4 ÷ 0.5) in electromagnetic component (e and γ including Cherenkov light) and the absence of it or a very small knee (∆γ ≈ 0.1 ÷ 0.2) in muonic and hadronic components. But, one could expect the inverse relationship in case of the astrophysical knee origin. A brief review of experimental data concerning this problem is given.

EAS Longitudinal Development and the Knee

“…If ∆γ=0.5, then expected values are: ∆β e ≈0.44 for electrons and ∆β h ≈0.6 for hadrons and muons. But this contradicts observations (see [6] and references there) where the knee in muonic and in hadronic components is equal to only ∆β h ≈0.1-0.2.…”

“…Absolutely new approach to this problem has been proposed in 2003 and details of the approach can be found elsewhere [5]. It has been also shown [6,7] that a lot of experiments contradict the hypothesis of the "knee" in primary spectrum and its astrophysical origin.…”

The knee in the cosmic ray energy spectrum from the simultaneous EAS charged particles and muon density spectra

“…Since α µ < α e , change in β µ should be larger than β e for a change in γ. Observationally, however, no significant change in β µ is found. This is why Stenkin objected the existence of a knee in the primary energy spectrum [8,9].…”

“…However, such a proposal has not received any support from the LHC experiment against the expectations. On the other hand Stenkin [8,9] refuted the reality of the knee in the primary cosmic ray energy spectrum on the ground that the knee has been noticed observationally only in the electromagnetic component of EAS but not in the muonic and the hadronic components of EAS. In other words the knee feature in the primary cosmic ray energy spectrum is not consistently revealed from electromagnetic, muonic and hadronic components of EAS.…”

“…In other words the knee feature in the primary cosmic ray energy spectrum is not consistently revealed from electromagnetic, muonic and hadronic components of EAS. Stenkin proposed an alternative explanation of the break in shower size spectrum in terms of coreless EAS [8,9]. Further a new experiment PRISMA has been proposed to investigate the situation [10].…”