Binary Neutron Star Mergers as the source of UHECRs

by Glennys R. Farrar (New York University)

Wednesday 2 Sept 2026, 11:30 → 12:30 Europe/Zurich

4/2-011 - TH common room (CERN)

Evidence in the Ultrahigh Energy Cosmic Ray data points to binary neutron star mergers as their source. I will review that evidence and report on several unique predictions that confirm this scenario:  

- The spectral shape including the cutoff rigidity, which agrees with observations.   

- A subdominant higher energy proton or helium component, seen at  >7-sigma significance in the Auger data.  Measuring the ratio between p and He in this high energy component will give a unique probe of r-process nucleosynthesis and the QCD quark matter equation of state, as will be explained. 

- A small population of particularly high energy events such as Telescope Array’s “Amaterasu”, several Auger events, and the earlier Fly’s Eye “OMG” event.

A prediction to be tested with future Gravitational Wave and neutrino observatories is that every EHE neutrino (above a few PeV) is accompanied by a co-directional gravitational wave from the BNS merger.