Very high energy emission as a probe of relativistic magnetic reconnection in pulsar winds

Iwona Mochol; Jerome Petri

doi:10.1093/mnrasl/slv018

paper

Very high energy emission as a probe of relativistic magnetic reconnection in pulsar winds

arXiv:1501.07123 · doi:10.1093/mnrasl/slv018

Abstract

The population of gamma-ray pulsars, including Crab observed in the TeV range, and Vela detected above 50 GeV, challenges existing models of pulsed high-energy emission. Such models should be universally applicable, yet they should account for spectral differences among the pulsars. We show that the gamma-ray emission of Crab and Vela can be explained by synchrotron radiation from the current sheet of a striped wind, expanding with a modest Lorentz factor $Γ ≲ 100$ in the Crab case, and $Γ ≲ 50$ in the Vela case. In the Crab spectrum a new synchrotron self-Compton component is expected to be detected by the upcoming experiment CTA. We suggest that the gamma-ray spectrum directly probes the physics of relativistic magnetic reconnection in the striped wind. In the most energetic pulsars, like Crab, with $E ˙_{38}^{3/2} / P_{- 2} ≳ 0.002$ (where $E ˙$ is the spin down power, $P$ is the pulsar period, and $X = X_{i} \times 1 0^{i}$ in CGS units), reconnection proceeds in the radiative cooling regime and results in a soft power-law distribution of cooling particles; in less powerful pulsars, like Vela, particle energization is limited by the current sheet size, and a hard particle spectrum reflects the acceleration mechanism. A strict lower limit on the number density of radiating particles corresponds to emission close to the light cylinder, and, in units of the GJ density, it is $≳ 0.5$ in the Crab wind, and $≳ 0.05$ in the Vela wind.

arXiv commentpublished version; corrected typo, added reference

Very high energy emission as a probe of relativistic magnetic reconnection in pulsar winds

Abstract

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