Acceleration of ultrahigh-energy cosmic rays in starburst superwinds

TL;DR

This paper explores the potential of starburst galaxy superwinds as sources of ultrahigh-energy cosmic rays, analyzing constraints, spectral compatibility, and neutrino emissions to support this acceleration mechanism.

Contribution

It provides new constraints and parameter adjustments for the starburst superwind acceleration model, demonstrating its consistency with observed UHECR energies and spectra.

Findings

UHECR acceleration above 10^{11} GeV is compatible with observations.

The model can produce hard source spectra matching Auger data.

Neutrino emission can distinguish between different acceleration models.

Abstract

The sources of ultrahigh-energy cosmic rays (UHECRs) have been stubbornly elusive. However, the latest report of the Pierre Auger Observatory provides a compelling indication for a possible correlation between the arrival directions of UHECRs and nearby starburst galaxies. We argue that if starbursts are sources of UHECRs, then particle acceleration in the large-scale terminal shock of the superwind that flows from the starburst engine represents the best known concept model in the market. We investigate new constraints on the model and readjust free parameters accordingly. We show that UHECR acceleration above about 10^{11} GeV remains consistent with observation. We also show that the model could accommodate hard source spectra as required by Auger data. We demonstrate how neutrino emission can be used as a discriminator among acceleration models.