Cosmic magnetic fields and implications for HE particle anisotropies

TL;DR

This review explores cosmic magnetic fields across different scales, their influence on high-energy cosmic ray propagation, and implications for anisotropies and source identification in the universe.

Contribution

It provides a comprehensive overview of magnetic fields in space and discusses their impact on ultra-high-energy cosmic ray anisotropies and source localization.

Findings

Magnetic fields influence cosmic ray propagation up to 100 Mpc.

Potential for cosmic ray source pointing above 10^19 eV.

Identification of candidate sources like AGN and starburst galaxies.

Abstract

I review what is known and surmised about magnetic fields in space, from our Milky Way environment to the distant Universe beyond the GZK horizon. This includes our gradually improving specification of the CR propagation environment within the Milky Way, the nearby universe within ~ 10 Mpc, and out to the GZK "horizon" near 100Mpc. Within these modest intergalactic distances we hope for some pointing capability for CR energies above ~ 1019eV, and for different species, as the observed event numbers accumulate in this range over the near future. The wider intergalactic propagation environment beyond the GZK horizon is also discussed. It sets a useful context for understanding other types of anisotropies, including sources of HE photons, neutrinos, leptons, etc. and for understanding relative time of arrival differences, such as those produced by lepton-photon cascades in the intergalactic medium. The global layout of potential UHECR sources is likely connected with the large scale structure (LSS) of cosmic filaments and voids, at least within ~ 100 Mpc. Possible source candidates for UHECR production are discussed, at various redshift ranges up to z ~ 2. Candidates discussed are AGN-jet sources, Centaurus A and more distant giant radio galaxies, and the possible indirect role of galaxies having a strong magnetized CR gas outflow that is driven by "starbursts" involving multiple supernovae and other energetic stellar events. Various analysis methods are described. I also discuss the current state of the results and near-future prospects for improving them.