TY  - JOUR
A1  - Fraschetti, F.
A1  - Pohl, Martin
T1  - Particle acceleration model for the broad-band baseline spectrum of the Crab nebula
JF  - Monthly notices of the Royal Astronomical Society
N2  - We develop a simple one-zone model of the steady-state Crab nebula spectrum encompassing both the radio/soft X-ray and the GeV/multi-TeV observations. By solving the transport equation for GeV-TeV electrons injected at the wind termination shock as a log-parabola momentum distribution and evolved via energy losses, we determine analytically the resulting differential energy spectrum of photons. We find an impressive agreement with the observed spectrum of synchrotron emission, and the synchrotron self-Compton component reproduces the previously unexplained broad 200-GeV peak that matches the Fermi/Large Area Telescope (LAT) data beyond 1 GeV with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) data. We determine the parameters of the single log-parabola electron injection distribution, in contrast with multiple broken power-law electron spectra proposed in the literature. The resulting photon differential spectrum provides a natural interpretation of the deviation from power law customarily fitted with empirical multiple broken power laws. Our model can be applied to the radio-to-multi-TeV spectrum of a variety of astrophysical outflows, including pulsar wind nebulae and supernova remnants, as well as to interplanetary shocks.
KW  - acceleration of particles
KW  - shock waves
KW  - cosmic rays
KW  - ISM: supernova remnants
Y1  - 2017
U6  - https://doi.org/10.1093/mnras/stx1833
SN  - 0035-8711
SN  - 1365-2966
VL  - 471
SP  - 4866
EP  - 4874
PB  - Oxford Univ. Press
CY  - Oxford
ER  -