Pulsar interpretation for the AMS-02 result

TL;DR

This paper explores whether nearby pulsars like Geminga or Monogem can explain the AMS-02 observed positron excess, fitting the data with single or multiple pulsar contributions and emphasizing the importance of future spectral measurements.

Contribution

It demonstrates that both single and multiple nearby pulsars can account for the AMS-02 positron data, supporting the pulsar origin hypothesis for high-energy positrons.

Findings

Single pulsars like Geminga can fit the data with spectral index ~2.

Multiple known pulsars can collectively explain the positron excess.

Future spectral measurements could confirm the pulsar contribution.

Abstract

The AMS-02 collaboration has just published a high precision measurement of the cosmic positron fraction $e^+/(e^- + e^+)$, which rises with energy from $\sim 5$ GeV to $\sim 350$ GeV. The result indicates the existence of primary electron/positron sources to account for the positron excess. In this work, we investigate the possibility that the nearby mature pulsars are the primary positron sources. By fitting the data we find that the positrons from a single nearby pulsar, such as Geminga or Monogem, with the spectral index $\alpha \sim 2$ can interpret the AMS-02 result. We also investigate the possibility that high energy positrons are generated by multiple known pulsars in the ATNF catalogue. Such a scenario can also fit the AMS-02 data well. Future precise measurements of fine structures in the positron spectrum would be a support to the pulsar scenario.