12-23 July 2021
Online
Europe/Berlin timezone

A combined fit of energy spectrum, shower depth distribution and arrival directions to constrain astrophysical models of UHECR sources

13 Jul 2021, 12:00
1h 30m
03

03

Talk CRI | Cosmic Ray Indirect Discussion

Speaker

Teresa Bister (RWTH Aachen University)

Description

The combined fit of the measured energy spectrum and shower depth distribution of ultra-high-energy cosmic rays is known to constrain the parameters of astrophysical scenarios with homogeneous source distributions. Further measurements show that the cosmic-ray arrival directions agree better with the directions and fluxes of catalogs of starburst galaxies and active galactic nuclei than with isotropy.
Here, we present a novel combination of both analyses. For that, a three-dimensional universe model containing a nearby source population and a homogeneous background source distribution is built, and its parameters are adapted using a combined fit of energy spectrum, shower depth distribution and energy-dependent arrival directions. The model takes into account a symmetric magnetic field blurring, source evolution and interactions during propagation.
We use simulated data, which resemble measurements of the Pierre Auger Observatory, to evaluate the method’s sensitivity. By that, we are able to verify that the source parameters as well as the fraction of events from the nearby source population and the size of the magnetic field blurring are determined correctly, and that the data is described by the fitted model including the catalog sources with their respective fluxes and three-dimensional positions. We demonstrate that by combining all three measurements we reach the sensitivity necessary to discriminate between the catalogs of starburst galaxies and active galactic nuclei.

Keywords

UHECR sources, SBG, AGN, combined fit

Collaboration Auger
Subcategory Experimental Results

Primary author

Teresa Bister (RWTH Aachen University)

Co-author

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