Modeling the spectral evolution of PWNe inside SNRs

TL;DR

This paper introduces a simplified model for the spectral evolution of Pulsar Wind Nebulae within Supernova Remnants, aiming to constrain system properties and understand particle acceleration mechanisms.

Contribution

It couples 1-D dynamical modeling with a 1-zone spectral description, providing a preliminary tool for analyzing PWN-SNR systems and revealing a common spectral break energy across sources.

Findings

Broken-power law injection spectrum fits all systems

Spectral break energy is similar across different sources

Implications for pulsar magnetospheres and particle acceleration

Abstract

We present a new model for the spectral evolution of Pulsar Wind Nebulae inside Supernova Remnants. The model couples the long-term dynamics of these systems, as derived in the 1-D approximation, with a 1-zone description of the spectral evolution of the emitting plasma. Our goal is to provide a simplified theoretical description that can be used as a tool to put constraints on unknown properties of PWN-SNR systems: a piece of work that is preliminary to any more accurate and sophisticated modeling. In the present paper we apply the newly developed model to a few objects of different ages and luminosities. We find that an injection spectrum in the form of a broken-power law gives a satisfactory description of the emission for all the systems we consider. More surprisingly, we also find that the intrinsic spectral break turns out to be at a similar energy for all sources, in spite of the differences mentioned above. We discuss the implications of our findings on the workings of pulsar magnetospheres, pair multiplicity and on the particle acceleration mechanism(s) that might be at work at the pulsar wind termination shock.