High energy cosmic ray self-confinement close to extragalactic sources

TL;DR

This paper demonstrates that ultra-high energy cosmic rays are self-confined near extragalactic sources due to plasma instabilities, with confinement energies depending on source luminosity and background magnetic fields.

Contribution

It introduces a model showing cosmic ray self-confinement near sources driven by plasma instabilities, linking confinement energies to source luminosity and magnetic field strength.

Findings

Cosmic rays are self-confined near sources for energies below a certain cutoff.

The confinement energy depends on source luminosity and magnetic field parameters.

Plasma instabilities create magnetic fluctuations that scatter and confine cosmic rays.

Abstract

The ultra-high energy cosmic rays observed at the Earth are most likely accelerated in extra-galactic sources. For the typical luminosities invoked for such sources, the electric current associated to the flux of cosmic rays that leave them is large. The associated plasma instabilities create magnetic fluctuations that can efficiently scatter particles. We argue that this phenomenon forces cosmic rays to be self-confined in the source proximity for energies $E<E_{\rm cut}$, where $E_{\rm cut}\approx 10^{7} L_{44}^{2/3}$ GeV for low background magnetic fields ($B_{0}\ll nG$). For larger values of $B_{0}$, cosmic rays are confined close to their sources for energies $E<E_{\rm cut}\approx 2\times 10^{8} \lambda_{10} L_{44}^{1/4} B_{-10}^{1/2}$ GeV, where $B_{-10}$ is the field in units of $0.1$ nG, $\lambda_{10}$ is its coherence lengths in units of 10 Mpc and $L_{44}$ is the source luminosity in units of $10^{44}$ erg/s.