On the Contribution of Unresolved Pulsars to the Ultra-high-energy Galactic Diffuse Gamma-Ray Emission

Abstract

The ultra high-energy (UHE) Galactic diffuse gamma-ray emission holds important information on the propagation of cosmic rays in the Galaxy. However, its measurements suffer from a contamination from unresolved sources whose contribution remains unclear. In this Letter, we propose a novel data-driven estimate of the contribution of unresolved pulsar wind nebulae and TeV halos based on the information present in the ATNF and the LHAASO catalogs. We find that in the inner Galaxy, this contribution is limited to $\sim 38\%\pm 10\%$ of the diffuse flux measured by LHAASO at $\sim 20\mathrm{TeV}$ in the case where all sources associated to pulsars contribute as unresolved sources, and this fraction drops with energy to less than $21\%\pm 6\%$ above $100\mathrm{TeV}$. In the outer Galaxy, this contribution is always subdominant. In particular, it reaches at most $\sim 18\%\pm 2\%$ at $10\mathrm{TeV}$ and is less than $\sim 7\%\pm 1\%$ above $\sim 25\mathrm{TeV}$. We conclude that the UHE Galactic diffuse gamma-ray emission cannot be dominated by unresolved pulsar sources above a few tens of $\mathrm{TeV}$.

Published in ApJL, 8 pages, 4 figures

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Cited by in corpus (7)

• Imprints of PeV cosmic-ray sources on the diffuse gamma-ray emission
• A discussion on the origin of the sub-PeV Galactic gamma-ray emission
• Quantitative constraint on the contribution of resolved gamma-ray sources to the sub-PeV Galactic diffuse gamma-ray flux measured by the Tibet ASγ experiment
• Leptonic and hadronic models of high-energy nebula around V4641 Sgr
• Particle Astrophysics with High and Ultrahigh Energy Neutrinos
• Interpreting the LHAASO Galactic diffuse emission data
• TeV-PeV Gamma-ray and Neutrino Emission in the Galactic Plane