Ultra-high energy Inverse Compton emission from Galactic electron accelerators

Abstract

It is generally held that >100 TeV emission from astrophysical objects unambiguously demonstrates the presence of PeV protons or nuclei, due to the unavoidable Klein-Nishina suppression of inverse Compton emission from electrons. However, in the presence of inverse Compton dominated cooling, hard high-energy electron spectra are possible. We show that the environmental requirements for such spectra can naturally be met in spiral arms, and in particular in regions of enhanced star formation activity, the natural locations for the most promising electron accelerators: powerful young pulsars. Our scenario suggests a population of hard ultra-high energy sources is likely to be revealed in future searches, and may also provide a natural explanation for the 100 TeV sources recently reported by HAWC.

Accepted for publication in ApJL

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• Multi-wavelength study of the galactic PeVatron candidate LHAASO J2108+5157
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• Investigating $\gamma$-ray halos around three HAWC bright sources in Fermi-LAT data
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• Ultra-high Energy Gamma-rays from Past Explosions in our Galaxy
• LHAASO J2226+6057 as a pulsar wind nebula
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• Dissecting the emission from LHAASO J0341+5258: implications for future multi-wavelength observations
• Pulsar Wind Nebulae
• Multiwavelength Investigation of $\gamma$-ray Source MGRO J1908+06 Emission Using Fermi-LAT, VERITAS, and HAWC
• Testing the Molecular Cloud Paradigm for Ultra-High-Energy Gamma Ray Emission from the Direction of SNR G106.3+2.7
• Revisiting the propagation of highly-energetic gamma rays in the Galaxy
• The Potential for Hadronic Particle Acceleration in Galactic Pulsar Wind Nebulae
• Particle acceleration to PeV energies in Pulsar Wind Nebula: a two zone model
• The primary proton spectrum of the hadronic PeVatron candidate HAWC J1825-134
• Deciphering the gamma-ray emission in the Cygnus region
• HAWC Study of the Ultra-High-Energy Spectrum of MGRO J1908+06