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arXiv · 2608.25497

Energy-dependent extension of the Crab Nebula as a diagnostic of ultrahigh-energy hadronic emission

Fang-Wu Lu·Bo-Tao Zhu·Ji-Yang Ren·Li Zhang
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Abstract

The energy-dependent apparent extension of the Crab Nebula, inconsistent with leptonic expectations between X-ray and TeV bands, can be naturally accounted for in a spatially resolved lepto-hadronic scenario. A transition to hadronic dominance occurs above $\sim400~\rm{TeV}$, with nearly pure hadronic emission at PeV energies. The predicted $68\%$ containment radius at $1.1~\rm{PeV}$ is $\sim1.4'$, about six times larger than in purely leptonic scenarios. This energy-dependent extension therefore provides an observable discriminator of the origin of ultra-high-energy gamma-ray emission in pulsar wind nebulae, offering a diagnostic of PeV hadronic acceleration in the Crab Nebula.

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Fang-Wu Lu, Bo-Tao Zhu, Ji-Yang Ren, Li Zhang. 2026-08-26. Energy-dependent extension of the Crab Nebula as a diagnostic of ultrahigh-energy hadronic emission. https://doi.org/10.1103/dnsv-plc9

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