Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula
Abstract
Bow-shock pulsar wind nebulae (PWNe) are synchrotron sources formed when the outflow of supersonic pulsars is confined by the surrounding interstellar medium. These sources are dominated by freshly injected particles, thus providing a unique laboratory for studying particle acceleration in relativistic outflows. The Mouse is a prototypical bow-shock PWN and is bright in the radio and X-ray bands, enabling detailed multi-wavelength spectral modeling. With data from 17 telescopes, the Mouse is detected from 118 MHz to 353 GHz, covering over 3 decades in frequency, and in X-rays from 0.5 to 30 keV. A clear spectral break is identified at 3.7 GHz. The radio spectrum exhibits a rising trend at low frequency, peaks at the break, and then declines. We find a change in spectral index Δα=0.65±0.05 across the break. We attribute this to an intrinsic cutoff or steepening in the injected particle distribution. This could indicate the characteristic energy of leptons leaving the pulsar magnetosphere, or energy dissipation after the particles cross the termination shock.
Versions
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BibTeX
@misc{shi2026evidence,
title = {{Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula}},
author = {Zhihong Shi and C. -Y. Ng and Niccol`o Bucciantini and B. M. Gaensler and Zhen Yan and David J. Wilner and Douglas C. -J. Bock and Hua-bai Li},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10041},
eprint = {2609.10041},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10041},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula
AU - Zhihong Shi
AU - C. -Y. Ng
AU - Niccol`o Bucciantini
AU - B. M. Gaensler
AU - Zhen Yan
AU - David J. Wilner
AU - Douglas C. -J. Bock
AU - Hua-bai Li
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.10041
UR - https://arxiv.org/abs/2609.10041
AB - Bow-shock pulsar wind nebulae (PWNe) are synchrotron sources formed when the outflow of supersonic pulsars is confined by the surrounding interstellar medium. These sources are dominated by freshly injected particles, thus providing a unique laboratory for studying particle acceleration in relativistic outflows. The Mouse is a prototypical bow-shock PWN and is bright in the radio and X-ray bands, enabling detailed multi-wavelength spectral modeling. With data from 17 telescopes, the Mouse is detected from 118 MHz to 353 GHz, covering over 3 decades in frequency, and in X-rays from 0.5 to 30 keV. A clear spectral break is identified at 3.7 GHz. The radio spectrum exhibits a rising trend at low frequency, peaks at the break, and then declines. We find a change in spectral index Δα=0.65±0.05 across the break. We attribute this to an intrinsic cutoff or steepening in the injected particle distribution. This could indicate the characteristic energy of leptons leaving the pulsar magnetosphere, or energy dissipation after the particles cross the termination shock.
ER -