A two-zone diffusion model fitted to HAWC morphology and spectrum data constrains Geminga's slow-diffusion zone to 30-70 pc and injection index p ≤ 2.17, reproducing AMS-02 positrons as a derived outcome.
Measurement of separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope
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abstract
We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting the Earth's shadow, which is offset in opposite directions for opposite charges due to the Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 GeV and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.
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astro-ph.HE 1years
2023 1verdicts
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Constraining the slow-diffusion zone size and electron injection spectral index for the Geminga pulsar halo
A two-zone diffusion model fitted to HAWC morphology and spectrum data constrains Geminga's slow-diffusion zone to 30-70 pc and injection index p ≤ 2.17, reproducing AMS-02 positrons as a derived outcome.