Benoît Cerutti (University of Colorado)
Jeudi 20 Septembre - 11 h 00
Salle Manuel Forestini - IPAG
The unexpected detection of bright short-lived gamma-ray flares in the Crab Nebula in 2010, has attracted considerable interests among observers and theorists. This discovery implies that electrons and positrons are accelerated to PeV (10^15 eV) energies in a milliGauss magnetic field, challenging the most established models of particle acceleration and pulsar wind nebulae. In this talk, I will argue that the flares could be powered by the rapid dissipation of magnetic energy via magnetic reconnection in the nebula. Using Particle-In-Cell simulations, I will show that relativistic reconnection accelerates and focuses particles into a narrow beam wiggling in the plane of the reconnection layer. The expected high-energy synchrotron emission is highly beamed, and exhibits ultra-rapid time variability. This scenario provides a viable explanation for the flares in the Crab Nebula. This study suggests that reconnection could be at the origin of other astrophysical flares, such as e.g., TeV gamma-ray flares in blazars. I will discuss a few examples.
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