A recent article from the Pierre Auger Collaboration links the direction of charged cosmic rays to possible extragalactic sites of emission. The correlation of the direction of such particles with the direction of the emitter allows constraining the value of large-scale magnetic fields B. Assuming for B a coherence length in the range between 1 Mpc and 10 Mpc, we find values of B between 0.3 and 0.9 nG.
@article{arxiv.0711.3346,
title = {Constraints on Large-Scale Magnetic Fields from the Auger Results},
author = {Alessandro De Angelis and Massimo Persic and Marco Roncadelli},
journal= {arXiv preprint arXiv:0711.3346},
year = {2008}
}