Toward a robust inference method for the likelihood of low-luminosity gamma-ray bursts to be progenitors of ultrahigh-energy cosmic rays correlating with starburst galaxies

TL;DR

This paper evaluates the likelihood that low-luminosity gamma-ray bursts are the sources of ultrahigh-energy cosmic rays correlated with starburst galaxies, concluding that such an association is unlikely at a 90% confidence level.

Contribution

It introduces a robust inference method to assess the connection between llGRBs and cosmic rays, challenging previous hypotheses of their association with starburst galaxies.

Findings

The correlation between llGRBs and starburst galaxies is statistically excluded at 90% confidence.

The proposed method provides a more reliable way to test the llGRB-UHECR connection.

Results suggest alternative sources should be considered for ultrahigh-energy cosmic rays.

Abstract

Very recently, the Pierre Auger Collaboration reported a $4.5\sigma$ correlation between the arrival directions of the highest energy cosmic rays and nearby starburst galaxies. The cosmic rays producing the anisotropy signal have been proposed to originate in low-luminosity gamma-ray bursts (llGRBs). On the basis of the well-justified assumption that at redshift $z<0.3$ the host metallicity is a good indicator of the llGRB production rate, we show that the association of llGRBs and the starbursts correlating with Auger data is excluded at the 90% confidence level.