The radio emission, X-ray emission, and hydrodynamics of G328.4+0.2: A comprehensive analysis of a luminous pulsar wind nebula, its neutron star, and the progenitor supernova explosion

We present new observational and modeling results obtained for the Galactic nonthermal radio source G328.4+0.2. Using X-ray data obtained by XMM-Newton, we confirm that its X-ray emission is heavily absorbed, has a spectrum best fitted by a power-law model of photon index Gamma = 2 with no evidence for a thermal component, comes from a region significantly smaller than the radio emission, and that the X-ray and radio emissions are significantly offset from each other. We also present the results of a new high-resolution (7") 1.4 GHz image of G328.4+0.2 obtained using ATCA and a deep search for radio pulsations using the Parkes radio telescope. By comparing this 1.4 GHz image with a similar resolution image at 4.8 GHz, we find that the radio emission has a flat spectrum (alpha approximate to 0; S-v alpha v(alpha)). Additionally, we are able to limit the pseudoluminosity of any pulsar to L-1400 equivalent to S(1400)400d(2) less than or similar to 30 mJy kpc(2) for the central radio pulsar, assuming a distance of 17 kpc. In light of these observational results, we test whether G328.4+0.2 is a pulsar wind nebula or an SNR that contains a large pulsar wind nebula using a simple hydrodynamic model for the evolution of a pulsar wind nebula inside an SNR. As a result of this analysis, we conclude that G328.4+0.2 is a young (less than or similar to 10,000 years old) pulsar wind nebula formed by a low magnetic field (less than or similar to 10(12) G) neutron star born spinning rapidly (less than or similar to 10 ms) expanding into an undetected SNR formed by an energetic (greater than or similar to 10(51) ergs), low ejecta mass (M-ej less than or similar to 5 M-circle dot) supernova explosion that occurred in a low-density (n similar to 0.03 cm(-3)) environment.