Pulsars Do Not Produce Sharp Features in the Cosmic-Ray Electron and Positron Spectra

Abstract

Pulsars are considered to be the leading explanation for the excess in cosmic-ray positrons detected by PAMELA and AMS-02. A notable feature of standard pulsar models is the sharp spectral cutoff produced by the increasingly efficient cooling of very-high-energy electrons by synchrotron and inverse-Compton processes. This spectral break has been employed to: (1) constrain the age of pulsars that contribute to the excess, (2) argue that a large number of pulsars must significantly contribute to the positron flux, and (3) argue that spectral cutoffs cannot distinguish between dark matter and pulsar models. We prove that this spectral feature does not exist -- it appears due to approximations that treat inverse-Compton scattering as a continuous, instead of as a discrete and catastrophic, energy-loss process. Astrophysical sources do not produce sharp spectral features via cooling, reopening the possibility that such a feature would provide incontrovertible evidence for dark matter.

5 pages, 3 figures. Appendices add 7 pages, 13 figures. Revised version matches version accepted by PRD

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Cited by in corpus (6)

• $\gamma$-Cascade V4: A Semi-Analytical Code for Modeling Cosmological Gamma-Ray Propagation
• Constraining the Milky Way's Pulsar Population with the Cosmic-Ray Positron Fraction
• PHECT: A lightweight computation tool for pulsar halo emission
• Discrete treatment of inverse Compton scattering: implications on parameter estimation in gamma-ray astronomy
• Possible counterpart signal of the Fermi bubbles at the cosmic-ray positrons
• Possible spectral irregularities in the AMS-02 positron spectrum