Spectral evolution of non-thermal electron distributions in intense radiation fields
arXiv:0708.1516 · doi:10.1051/0004-6361:20078298
Abstract
(abridged) Models of many astrophysical gamma-ray sources assume they contain a homogeneous distribution of electrons that are injected as a power-law in energy and evolve by interacting with radiation fields, magnetic fields and particles in the source and by escaping. This problem is particularly complicated if the radiation fields have higher energy density than the magnetic field and are sufficiently energetic that inverse Compton scattering is not limited to the Thomson regime. We present a simple, time-dependent, semi-analytical solution of the electron kinetic equation that treats both continuous and impulsive injection, cooling via synchrotron and inverse Compton radiation, (taking into account Klein-Nishina effects) and energy dependent particle escape. The kinetic equation for an arbitrary, time-dependent source function is solved by the method of Laplace transformations. Using an approximate expression for the energy loss rate that takes into account synchrotron and inverse Compton losses including Klein-Nishina effects for scattering off an isotropic photon field with either a power-law or black-body distribution, we find explicit expressions for the cooling time and escape probability of individual electrons. This enables the full, time-dependent solution to be reduced to a single quadrature. From the electron distribution, we then construct the time-dependent, multi-wavelength emission spectrum. We compare our solutions with several limiting cases and discuss the general appearance and temporal behaviour of spectral features (i.e., cooling breaks, bumps etc.). As a specific example, we model the broad-band energy spectrum of the open stellar association Westerlund-2 at different times of its evolution, and compare it with observations.
arXiv comment14 pages, 8 figures, acccepted for publication in A&A
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Cited by in corpus (17)
- On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
- Discovery of extended VHE γ-ray emission from the vicinity of the young massive stellar cluster Westerlund 1
- On the evolution of the Gamma- and X-ray luminosities of Pulsar Wind Nebulae
- Revisiting the Westerlund 2 Field with the H.E.S.S. Telescope Array
- Evolving Nonthermal Electrons in Simulations of Black Hole Accretion
- A method for localizing energy dissipation in blazars using Fermi variability
- Suzaku Observation of the Diffuse X-Ray Emission from the Open Cluster Westerlund 2: a Hypernova Remnant?
- Colliding-wind binary systems: Diffusive shock acceleration and non-thermal emission
- Probing the hadronic nature of the gamma-ray emission associated with Westerlund 2
- The jet and arc molecular clouds toward Westerlund 2, RCW 49, and HESS J1023-575; 12CO and 13CO (J=2-1 and J=1-0) observations with NANTEN2 and Mopra Telescope
- Evolution of non-thermal emission from shell associated with AGN jets
- X-ray emission from Westerlund 2 detected by SRG/ART-XC and Chandra: search for radiation of TeV leptons
- A 3D Diffusive and Advective Model of Electron Transport Applied to the Pulsar Wind Nebula HESS J1825-137
- High-(Energy)-Lights -- The Very High Energy Gamma-Ray Sky
- Locating the VHE source in the Galactic Centre with milli-arcsecond accuracy
- Explaining the extended GeV gamma-ray emission adjacent to HESS J1825-137
- Non-Thermal emissions from shocked shells driven by powerful AGN jets