Closing the net on transient sources of ultra-high-energy cosmic rays

Understand

Arrival directions of ultra-high-energy cosmic rays (UHECRs) observed above $4\times10^{19}\,$eV provide evidence of localized excesses that are key to identifying their sources.

• We leverage the 3D matter distribution from optical and infrared surveys as a density model of UHECR sources, which are considered to be transient.
• Agreement of the sky model with UHECR data imposes constraints on both the emission rate per unit matter and the time spread induced by encountered turbulent magnetic fields.
• Based on radio measurements of cosmic magnetism, we identify the Local Sheet as the magnetized structure responsible for the kiloyear duration of UHECR bursts for an observer on Earth and find that the turbulence amplitude must be within $0.5-20\,$nG for a coherence length of $10\,$kpc.