High-Statistics Measurement of the Cosmic-Ray Electron Spectrum with H.E.S.S.

Area of Science:

• Astrophysics
• Particle Physics
• Cosmic Ray Physics

Background:

• Cosmic-ray electrons and positrons (CRe) at very high energies are crucial for probing local accelerators.
• Their rapid cooling limits propagation, making them sensitive probes of nearby sources and exotic physics like dark matter annihilation.
• Understanding the CRe spectrum provides insights into astrophysical processes and fundamental physics.

Purpose of the Study:

• To present a high-statistics measurement of the cosmic-ray electron and positron spectrum from 0.3 to 40 TeV.
• To search for spectral features that could indicate nearby CRe accelerators or exotic production mechanisms.
• To constrain models of CRe propagation and potential dark matter signals.

Main Methods:

• Utilized the High Energy Stereoscopic System (H.E.S.S.) for data collection.
• Achieved a proton rejection power exceeding 10^4.
• Analyzed the CRe spectrum over two orders of magnitude in energy.

Main Results:

• The measured CRe spectrum from 0.3 to 40 TeV is well-described by a broken power law.
• A spectral break was observed around 1 TeV, with the spectral index changing from 3.25±0.02(stat)±0.2(sys) to 4.49±0.04(stat)±0.2(sys).
• No other distinct spectral features were found at multi-TeV energies.

Conclusions:

• The observed spectral break provides information about the energy spectrum of local cosmic-ray sources.
• The absence of additional features constrains the existence of nearby CRe accelerators and exotic propagation models.
• The results place limits on dark matter annihilation scenarios contributing to the local CRe flux.