Ultra-High Energy Cosmic Rays from the Galactic Center

TL;DR

This paper proposes that past accretion events and associated shocks in the Galactic center could explain the origin of ultra-high energy cosmic rays above 1 PeV, with confinement in a large Galactic halo.

Contribution

It introduces a model linking Galactic center activity to ultra-high energy cosmic rays and discusses the magnetic field conditions for their confinement.

Findings

Cosmic rays above 1 PeV can be explained by past Galactic center activity.

Galactic halo magnetic field as low as 2×10^{-7} G can effectively confine these cosmic rays.

Extended Galactic halo of several hundred kiloparsecs is crucial for cosmic ray confinement.

Abstract

It is shown that Eddington-like accretion event in the Galactic center several million years ago and particle acceleration at accompanying shocks and jets could explain the observed cosmic ray spectrum at energies above 1 PeV. Cosmic ray particles are confined in extended (several hundred kiloparsec in size) Galactic halo. It is shown that the halo magnetic field could be as small as $2\times 10^{-7}$ G for the effective confinement.