Nucleonic gamma-ray production in Vela X

Abstract

Context. The recently discovered extended very high energy gamma-ray (E > 0.1 = 10 11 eV) emission from at least three pulsar wind nebula systems (MSH 15-52, G18.0-07, and Vela X) could be hinting at a possibly new class of objects which is called in the following TeV plerions. In some of these systems, particle acceleration could be driven by ions in the relativistic pulsar wind. These ions are expected to produce gamma-ray emission via inelastic scattering with the ambient medium. Aims. The gamma-ray emission from the Vela plerion associated with the pulsar PSR B0833-45 is investigated Methods. We calculate the gamma-ray emission in the framework of nucleonic gamma-ray production including the synchrotron and inverse Compton emission from primary and secondary electrons and compare the model with observational data. Results. The spectra calculated in this model give a very good description of the gamma-ray data. The required energy in nuclei is W p = 1.3 x 10 49 (n/0.6 cm -3 ) -1 erg for protons and W Fe ≈ 10 48 erg for iron nuclei released in the pulsar wind. The secondary electrons produce optical to soft X-ray emission at the level of ≈10 32 erg/s. We give a prediction for the ν μ and V e neutrino emission including a simple parameterization of the ν μ flux useful for calculating detection rates in next generation neutrino telescopes. Conclusions. The observed gamma-ray emission can be produced by a pulsar wind which carries a large fraction of the spin down luminosity in the form of relativistic nuclei. We predict the neutrino flux as a unique signature for this model. Based upon this prediction, the Vela plerion would be one of the best known candidates for detection with next generation neutrino telescopes.