The evolution of a pulsar wind nebula ( PWN ) inside a supernova remnant ( SNR ) is sensitive to properties of the central neutron star , pulsar wind , progenitor supernova , and interstellar medium .
These properties are both difficult to measure directly and critical for understanding the formation of neutron stars and their interaction with the surrounding medium .
In this paper , we determine these properties for PWN G54.1+0.3 by fitting its observed properties with a model for the dynamical and radiative evolution of a PWN inside an SNR .
Our modeling suggests that the progenitor of G54.1+0.3 was an isolated \sim 15 - 20 M _ { \odot } star which exploded inside a massive star cluster , creating a neutron star initially spinning with period P _ { 0 } \sim 30 - 80 ~ { } { ms } .
We also find that \gtrsim 99.9 \% of the pulsar ’ s rotational energy is injected into the PWN as relativistic electrons and positrons whose energy spectrum is well characterized by a broken power-law .
Lastly , we propose future observations which can both test the validity of this model and better determine the properties of this source – in particular , its distance and the initial spin period of the central pulsar .