Astrophysical models to interpret the Pierre Auger Observatory data
Abstract
The Pierre Auger Observatory has measured the spectrum of ultra-high-energy cosmic rays with unprecedented precision, as well as the distribution of the depths of the maximum of the shower development in the atmosphere, which provide a reliable estimator of the mass composition. The measurements above 10[sup]17.8 eV can be interpreted assuming two populations of uniformly distributed sources, one with a soft spectrum dominating the flux below few EeV, and another one with a very hard spectrum dominating above that energy. When considering the presence of intense extragalactic magnetic fields between our Galaxy and the closest sources and a high-energy population with low spatial density, a magnetic horizon appears, suppressing the cosmic ray's flux at low-energies, which could explain the very hard spectrum observed at Earth. The distribution of arrival directions, which at energies above 32 EeV shows indications of a correlation with a population of starburst galaxies or the radio galaxy Centaurus A (Cen A), are also important to constrain the sources. It is shown that adding a fractional contribution from these sources of about 20% on top of an homogeneous background leads to an improvement of the model likelihood.
Keywords
ultra-high-energy cosmic rays;UHECR energy spectrum;UHECR mass composition;UHECR anisotropies;UHECR propagation;UHECR data interpretation;extragalactic magnetic fields;starburst galaxies;Centaurus A;Pierre Auger Observatory;
Data
| Language: | English |
|---|---|
| Year of publishing: | 2025 |
| Typology: | 1.08 - Published Scientific Conference Contribution |
| Organization: | UNG - University of Nova Gorica |
| UDC: | 539.1 |
| COBISS: |
230054147
|
| ISSN: | 1824-8039 |
| Views: | 346 |
| Downloads: | 7 |
| Average score: | 0 (0 votes) |
| Metadata: |
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Other data
| Pages: | 8 str. |
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| DOI: | 10.22323/1.484.0015 |
| ID: | 26106971 |
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