Strangelets and the TeV-PeV cosmic-ray anisotropies

TL;DR

This paper explores how strangelets emitted from neutron star transitions, neutralized in molecular clouds, could explain the observed cosmic-ray anisotropies in the TeV-PeV range.

Contribution

It proposes a novel model linking strangelet emission and neutralization in molecular clouds to cosmic-ray hotspots, matching observations.

Findings

Strangelet emission can produce anisotropies consistent with observations.

Neutralization in molecular clouds explains the localized hotspots.

Model reproduces the distribution and size of observed cosmic-ray excess regions.

Abstract

Several experiments (e.g., Milagro and IceCube) have reported the presence in the sky of regions with significant excess in the arrival direction distributions of Galactic cosmic rays in the TeV to PeV energy range. Here we study the possibility that these hotspots are a manifestation of the peculiar nature of these cosmic rays, and of the presence of molecular clouds near the sources. We propose that stable quark matter lumps or so-called "strangelets" can be emitted in the course of the transition of a neutron star to a more compact astrophysical object. A fraction of these massive particles would lose their charge by spallation or electron capture in molecular clouds located in the immediate neighborhood of their source, and propagate rectilinearly without decaying further, hence inducing anisotropies of the order of the cloud size. With reasonable astrophysical assumptions regarding the neutron star transition rate, strangelet injection and neutralization rates, we can reproduce successfully the observed hotspot characteristics and their distribution in the sky.