# On the Gamma-ray Nebula of Vela Pulsar. II. the Soft Spectrum of the Extended Radio Nebula

## TL;DR

This paper explains the broadband gamma-ray spectrum of the Vela X pulsar wind nebula's extended radio nebula by modeling shock interactions and electron dynamics, revealing how reverberation phases influence the observed spectrum.

## Contribution

It provides a detailed interpretation of the ERN's broadband spectrum, emphasizing the role of reverse shock interactions and nebula compression in shaping the electron spectrum.

## Key findings

- The GeV cutoff is due to reverse shock-PWN interaction.
- Reverberation compresses the ERN, enhancing magnetic fields.
- Electron spectrum explains the broadband emission satisfactorily.

## Abstract

The Vela\,X pulsar wind nebula (PWN) is characterized by the extended radio nebula (ERN) and the central X-ray "cocoon". We have interpreted the $\gamma$-ray spectral properties of the cocoon in the sibling paper (Bao et al.\,2019); here, we account for the broadband photon spectrum of the ERN. Since the diffusive escape of the electrons from the TeV emitting region is expected to play an insignificant role in shaping the spectrum of the ERN, we attribute the GeV cutoff of the ERN to the reverse shock-PWN interaction. Due to the disruption of the reverse shock, most of plasma of the PWN is driven into the ERN. During the subsequent reverberation phase, the ERN could be compressed by a large factor in radius, and the magnetic field in the ERN is thus significantly enhanced, burning off the high energy electrons. We thus obtain the electron spectrum of the ERN and the broadband spectrum of the ERN are explained satisfactorily.