UHECR Signatures and Sources

Abstract

We discuss recent results on the clustering, composition and distribution of Ultra-High Energy Cosmic Rays (UHECR) in the sky; from the energy of several tens of EeV in the dipole anisotropy, up to the highest energy of a few narrow clusters, those of Hot Spots. Following the early UHECR composition records deviations from proton we noted that the UHECR events above 40 EeV can be made not just by any light or heavy nuclei, but mainly by the lightest ones as He,D, Li,Be. The remarkable Virgo absence and the few localized nearby extragalactic sources, such as CenA, NGC 253 and M82, are naturally understood: lightest UHECR nuclei cannot reach us from the Virgo distance of twenty Mpc, due to their nuclei fragility above a few Mpc distances. Their deflection and smearing in wide hot spots is better tuned to the lighter nuclei than to the preferred proton or heavy nuclei candidate courier. We note that these lightest nuclei still suffer of a partial photodistruction even from such close sources. Therefore, their distruption in fragments, within few tens EeV multiplet chain of events, have been expected and later on observed by Auger collaboration, nearly a decade ago. These multiplet presences, strongly correlate with the same CenA, NGC253 sources. The statistical weight of such correlation is reminded. We conclude that the same role of NGC 253 clustering at lower energies could also feed the Auger dipole anisotropy at lower energy ranges. Such lower energy anisotropy could be fed and integrated by nearest Vela, Crab, LMC and Cas A contributes. In our present UHECR model, based on lightest nuclei in local volumes of a few Mpcs, closest AGN, Star-Burst or very close SNR are superimposing their signals, frozen in different epochs, distances and directions, feeding small and wide anisotropy. Possible tests to confirm, or untangle the current model from alternative ones, are suggested and updated.

UHECR multiplets versus Hot spots clustering in AUGER sky: the forgotten signals

“…These first candidate sources, as well as NGC 253, have been discussed since 2015 [10], [11]. In particular we noted the growing signals around , LMC, SMC and Crab in nearby sky, possibly explained, (now, also or mainly) by NGC 253 multiplets, that are feeding the low energy dipole Auger anisotropy [5]. There is, nevertheless, still much attention and suggestions for a far (> hundred Mpc) UHECR candidature.…”

“…The UHECR fragmentation in multiplets ,forseen for lightest nuclei before the observations, toward two main AGN sources is an obvious confirm of this scenario. The presence at edge energies of heavy (like Ni, Co, Fe) nuclei, might explain , by their largest bending, (originated mostly within our galaxy), bending able to smear and uncorrelate UHECR -to their sources events, possibly in correlation with tens TeV anisotropy sky [7] [5].…”

“…At higher energies, > 60 EeV, UHECR light or even heavy nuclei rise their role, ruling at 70− > 100 EeV energy edges. These changes may explain the complex evolution in UHECR clustering [5,6]. The absence of proton at UHECR at 40 EeV, explain the absence of narrow angle hot spot clustering, and justify the mysterious missing of Virgo.…”