| In this thesis, information concerning the energetics and environments of isolated young neutron star is used to study the formation and physical properties of these objects. I first present evidence that compact X-ray source, 1E 1547.0--5408, is a magnetar---a neutron star with an extremely strong magnetic field. I then present the results of radio observations of SGR 1806--20 after the 2004 December 27 giant flare which detected a new, variable radio source at the position of this magnetar. Measurements of the flux, position, size, and orientation of this source suggest that the observed radio emission is being powered by the interaction between material ablated off the surface of this neutron star during the giant flare and the surrounding ambient medium, and that this emission is now dominated by hotspots in the layer of shocked ambient material which surrounds the neutron star ejecta. Lastly, I present a hydrodynamic model for the evolution of a pulsar wind nebula (PWN) inside a supernova remnant (SNR), and use this model to infer the properties of the progenitor supernova and central neutron star for three objects---SNR G292.0+1.8, PWN 3C 58, and non-thermal Galactic radio source G328.4+0.2. I find that, if G292.0+1.8 is a SNR where the PWN has not yet collided with the reverse shock, as suggested by the weakness of S, Si, and Fe lines in the thermal X-ray spectrum of this source, G292.0+1.8 was most likely created in a low kinetic energy ( ≲ 1051 ergs), high ejecta mass ( ≳ 10 M⊙ ) explosion. For 3C 58, I am unable to find a combination of supernova explosion energy and ejecta mass, ambient density, and neutron star initial period and braking index which can reproduced the observed size, expansion velocity, and mass of thermal X-ray emitting material of this PWN if it was created during SN 1181. If I relax this restriction on the age of 3C 58, we find that the observed properties of this source, along with the X-ray non-detection of a SNR around this source, implies that 3C 58 is being powered by a neutron star with a braking index < 2.4 and an initial period ≈ 30--40 ms that was produced in a supernova explosion with a very low kinetic energy (∼ 1049--1050 ergs) and average-to-high ejecta mass (∼ 4--10 M⊙ ). Finally, for G328.4+0.2, I find that this source is a PWN inside an undetected SNR powered by a neutron star with a lower than average strength dipole component to the surface magnetic field < 1012 G born spinning rapidly ( ≲ 10 ms) produced in an average kinetic energy ( ≳ 1051 ergs) but low ejecta mass ( ≲ 4 M⊙ ) supernova. |
