Is the PAMELA anomaly caused by the supernova explosions near the Earth?

TL;DR

This paper proposes that the PAMELA positron anomaly is caused by recent supernova explosions near Earth within a dense gas cloud, producing a harder spectrum of electrons and positrons and predicting an anti-proton flux excess at high energies.

Contribution

It introduces a novel scenario linking nearby supernovae in dense gas clouds to the PAMELA positron excess, with specific spectral predictions.

Findings

Positron excess can be explained by supernovae in dense gas clouds.

Predicted anti-proton flux exceeds background above 100 GeV.

Results are consistent with observations from Fermi, HESS, PPB-BETS, and ATIC.

Abstract

We show that the anomaly of the positron fraction observed by the PAMELA experiment can be attributed to recent supernova explosion(s) in a dense gas cloud (DC) near the Earth. Protons are accelerated around the supernova remnant (SNR). Electrons and positrons are created through hadronic interactions inside the DC. Their spectrum is harder than that of the background because the SNR spends much time in a radiative phase. Our scenario predicts that the anti-proton flux dominates that of the background for >~100 GeV. We compare the results with observations (Fermi, HESS, PPB-BETS, and ATIC).