Reanalysis of the Pulsar Scenario to Explain the Cosmic Positron Excess Considering the Recent Developments
The slow diffusion of cosmic rays could be common around pulsars as indicated by the recent observations of HAWC, which can significantly change the pulsar interpretation of the well-known positron excess. Meanwhile, the latest measurement by AMS-02 shows a clear high-energy cutoff in the positron spectrum. Here, we check all the identified pulsars under the two-zone diffusion model to explain the new AMS-02 data. We find that the candidates must be nearby and middle-aged. Geminga, which was generally believed to be a very likely candidate, has recently been disfavored by Fermi-LAT observations of the GeV γ-ray flux. Following recent studies which indicate that PSR B1055−52 is much closer to the Earth than previously assumed, we propose for the first time that PSR B1055−52 is the most promising source of the positron excess. PSR B1055−52 can well reproduce both the intensity and the high-energy cutoff of the AMS-02 positron spectrum.