# Universal cosmic rays energy spectrum and the mass composition at the 'ankle' and above

## TL;DR

This paper combines data from major observatories to analyze the energy spectrum and composition of ultra high-energy cosmic rays, emphasizing the transition from Galactic to extragalactic sources at the 'ankle' and exploring source distribution effects.

## Contribution

It introduces a combined 'world average' spectrum and analyzes mass composition and source distribution, highlighting the Galactic source deficit near Earth.

## Key findings

- Evidence of a transition from Galactic to extragalactic cosmic rays at the ankle.
- Identification of a deficit of nearby extragalactic sources of UHECRs.
- Analysis of the impact of source distribution on cosmic ray composition.

## Abstract

We have used recently published data from the Pierre Auger Observatory and the Telescope Array Project to conclude some inferences concerning the origin and composition of ultra high-energy cosmic rays (UHECR). We advocate for model the UHECR flux as a combination of the Galactic and Extragalactic components exchanging the dominant role at the famous feature of the energy spectrum called 'the ankle'. We put a special emphasis on the individual experiment energy resolution and possible biases it introduces. We have eventually combined the data from both big experiments to the one 'world average' UHECR spectrum and we used it, supported by the analysis of the distribution of the Extensive Air Shower (EAS) development maximum depth to find the UHECR mass composition of both: Galactic and Extragalactic components. We studied the dependence of the on mass composition on the cosmic ray source distribution in space. We present results for some models existing in the literature. We found the evidence of the deficit of Extragalactic sources in the vicinity of the Galaxy of the the UHECR, what is in concordance with the small scale anisotropy analysis results.