Kachelriess will review the status of ultrahigh-energy cosmic ray (UHECR) physics. After introducing the main experimental results and summarizing possible interpretations, he will discuss observational and theoretical constraints on the sources of UHECRs. He will also briefly comment on the role of magnetic fields, then discuss a recent analysis of radio galaxies as the dominant extragalactic UHECR sources. In particular, Kachelriess argues that scenarios where few local sources like Fornax A and Virgo A dominate the flux above the ankle, while low-luminosity radio galaxies contribute an isotropic background dominating below the ankle, provide a good fit to the spectrum, composition and anisotropy data.

Sponsored by the McDonnell Center for the Space Sciences.

Contact physics@wustl.edu for Zoom link.

Kachelriess will review the status of ultrahigh-energy cosmic ray (UHECR) physics. After introducing the main experimental results and summarizing possible interpretations, he will discuss observational and theoretical constraints on the sources of UHECRs. He will also briefly comment on the role of magnetic fields, then discuss a recent analysis of radio galaxies as the dominant extragalactic UHECR sources. In particular, Kachelriess argues that scenarios where few local sources like Fornax A and Virgo A dominate the flux above the ankle, while low-luminosity radio galaxies contribute an isotropic background dominating below the ankle, provide a good fit to the spectrum, composition and anisotropy data.

Sponsored by the McDonnell Center for the Space Sciences.

Contact physics@wustl.edu for Zoom link.