Klein-Nishina steps in the energy spectrum of galactic cosmic ray electrons

Abstract

The full Klein-Nishina cross section for the inverse Compton scattering interactions of electrons implies a significant reduction of the electron energy loss rate compared to the Thomson limit when the electron energy exceeds the critical Klein-Nishina energy E_K = gamma_K * m_e c^2 = 0.27 m_e^2 c^2/(k_BT), where T denotes the temperature of the photon graybody distribution. As a consequence the total radiative energy loss rate of single electrons exhibits sudden drops in the overall energy loss rate ~ gamma ^2 - dependence when the electron energy reaches the critical Klein-Nishina energy. The strength of the drop is proportional to the energy density of the photon radiation field. The diffuse galactic optical photon fields from stars of spectral type B and G-K lead to critical Klein-Nishina energies of 40 and 161 GeV, respectively. Associated with the drop in the loss rate are sudden increases (Klein-Nishina steps) in the equilibrium spectrum of cosmic ray electrons. Because the radiative loss rate of electrons is the main ingredient in any transport model of high-energy cosmic ray electrons, Klein-Nishina steps will modify any calculated electron equilibrium spectrum irrespective of the electron sources and spatial transport mode. To delineate most clearly the consequences of the Klein-Nishina drops in the radiative loss rate, we chose as illustrative example the simplest realistic model for cosmic ray electron dynamics in the Galaxy, consisting of the competition of radiative losses and secondary production by inelastic hadron-hadron collisions. We demonstrate that the spectral structure in the FERMI and H.E.S.S. data is well described and even the excess measured by ATIC might be explained by Klein-Nishina steps.

References in corpus (6)

• Observation of an anomalous positron abundance in the cosmic radiation
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Probing the ATIC peak in the cosmic-ray electron spectrum with H.E.S.S
• Galactic secondary positron flux at the Earth
• On the Energy Spectra of GeV/TeV Cosmic Ray Leptons
• Astrophysical Uncertainties in the Cosmic Ray Electron and Positron Spectrum From Annihilating Dark Matter

Cited by in corpus (45)

• Galactic electrons and positrons at the Earth:new estimate of the primary and secondary fluxes
• Two-zone diffusion of electrons and positrons from Geminga explains the positron anomaly
• $e^{\pm }$ Excesses in the Cosmic Ray Spectrum and Possible Interpretations
• AMS02 results support the secondary origin of cosmic ray positrons
• Constraints on Decaying Dark Matter from the Isotropic Gamma-Ray Background
• The very-high energy emission from pulsars: a case for inverse Compton scattering
• Galactic factories of cosmic-ray electrons and positrons
• White Dwarf Pulsars as Possible Cosmic Ray Electron-Positron Factories
• Diffuse Hard X-ray Emission in Starburst Galaxies as Synchrotron from Very High Energy Electrons
• The diffuse gamma-ray flux associated with sub-PeV/PeV neutrinos from starburst galaxies
• Self-Generated Cosmic-Ray Turbulence Can Explain the Morphology of TeV Halos
• Galactic outflow driven by the active nucleus and the origin of the gamma-ray emission in NGC 1068
• Explanation of the knee-like feature in the DAMPE cosmic $e^{-}+e^{+}$ energy spectrum
• Cosmic-ray positrons from millisecond pulsars
• X-ray Through Very-High-Energy Intrabinary Shock Emission from Black Widows and Redbacks
• Non-thermal radio emission from O-type stars. IV. Cyg OB2 No. 8A
• The Highest Energy HAWC Sources are Likely Leptonic and Powered by Pulsars
• Klein-Nishina effect and the cosmic ray electron spectrum
• Signature of Energy Losses on the Cosmic Ray Electron Spectrum
• Constraints on dark matter models from a Fermi LAT search for high-energy cosmic-ray electrons from the Sun
• Perspective on the cosmic-ray electron spectrum above TeV
• Numerical study of Kelvin-Helmholtz instability and its impact on synthetic emission from magnetized jets
• Reanalyze the pulsar scenario to explain the cosmic positron excess considering the recent developments
• Anisotropic diffusion cannot explain TeV halo observations
• Hadronuclear interactions in the jet of low TeV luminosity AGN: Implications for the low-state very-high-energy gamma-ray emission
• Novel interpretation of the latest AMS-02 cosmic-ray electron spectrum
• Breaking the Radio - Gamma-Ray Connection in Arp 220
• Pulsars Do Not Produce Sharp Features in the Cosmic-Ray Electron and Positron Spectra
• Discriminating Local Sources of High-Energy Cosmic Electrons and Positrons by Current and Future Anisotropy Measurements
• Constraining the Emission Geometry and Mass of the White Dwarf Pulsar AR Sco using the Rotating Vector Model
• Cosmic Ray Anomalies from the MSSM?
• High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies
• Study of maximum electron energy of sub-PeV pulsar wind nebulae by multiwavelength modelling
• On the PeV knee of cosmic rays spectrum and TeV cutoff of electron spectrum
• A Broadband Emission Model of Magnetar Wind Nebulae
• Pamela, FGST and Sub-Tev Dark Matter
• Probing the pulsar population of Terzan 5 via spectral modeling
• Synchrotron and Compton Spectra from a Steady-State Electron Distribution
• The Contribution of Millisecond Pulsars to the Galactic Cosmic-Ray Lepton Spectrum
• Determination of Acceleration Mechanism Characteristics Directly and Non-Parametrically from Observations: Application to Supernova Remnants
• The physical properties of $\gamma$-ray quiet flat-spectrum radio quasars: why are they undetected by $Fermi$-LAT?
• The Cherenkov Telescope Array Will Test Whether Pulsars Generate the Galactic Center Gamma-Ray Excess
• Probing the astrophysical origin of high-energy cosmic-ray electrons with Monte Carlo simulation
• Origin Of The Cosmic Ray Positrons Observed Near Earth- Meson Decay Or Dark Matter Decay?
• Discrete treatment of inverse Compton scattering: implications on parameter estimation in gamma-ray astronomy