Past Events

Abstract
 

A bow-shock pulsar wind nebula (BSPWN) is a synchrotron bubble produced by a fast-moving pulsar, whose relativistic wind is shocked by the surrounding environment. BSPWNe are particle acceleration sites, and hence provide an ideal testing platform for the relativistic particle acceleration theories. In contrast to early-stage PWNe, parent supernova remnants do not contribute in the formation of BSPWNe, so BSPWNe have relatively steady structures, which allow simple spectral modelling. Particle acceleration mechanisms can be tested by inferring the injected particle distributions. Therefore, I carried out 3-GHz D-configuration deep Very Large Array radio searches for three BWPWNe, namely, PWN B0355+54, PWN J0357+3205, PWN J1740+1000, where no extended emission was observed. I used the measured 3σ flux density limits to constrain spectral models. In addition, we reanalysed multi-wavelength data of the Mouse (G359.23−0.82) in the literature. This object is a prototypical BSPWN, which is bright in both radio and X-ray, and hence favours multi-wavelength modelling. A spectral energy distribution of the Mouse was constructed with the radio, infrared, X-ray, and gamma-ray data. Then, I developed a one-zone static model to probe and compare three injected particle distributions resulted from different particle acceleration mechanisms, which are a single power law (PL), a broken power law (BPL), and a relativistic Maxwellian distribution with a high-energy power law tail. The results favour BPL as well as a relativistic Maxwellian distribution with a high-energy power law tail injected spectra, but not PL, indicating that simple predictions from conventional Fermi acceleration theory cannot explain the Mouse observations. Moreover, high-frequency radio and infrared observations are needed in order to provide a more complete wavelength coverage that enable more detailed modelling to be done. In this way, further statistical tests can be performed to determine the best-fit injected particle distribution, and therefore the most favourable particle acceleration mechanism.