Flux Evolution of PSR B0540--69 and the Spectral Energy Distribution of its Pulsar Wind Nebula
Abstract
The young Crab-like pulsar PSR B0540--69, located in the Large Magellanic Cloud, underwent a spin-down rate transition (SRT) in 2011 December, after which its pulsar wind nebula (PWN) was reported to brighten up to 2018. In this work, we extend the study of its X-ray and γ-ray flux evolution through 2026 by combining observations from multiple X-ray instruments with data from the Fermi Large Area Telescope, thereby constructing a flux history of the PSR+PWN system spanning more than two decades. We find that the enhanced X-ray luminosity of the PSR+PWN system has persisted for more than 14 yr after the SRT, up to early 2026, whereas the pulsed X-ray flux remains unchanged across all epochs. This confirms that the brightening originates from the PWN. In the γ-ray band, neither the pulsed nor the non-pulsed flux shows any detectable long-term variation between 2008 and 2025. Together, these results imply that the additional spin-down energy released at the SRT has been continuously injected into the PWN over decades, placing strong constraints on the energy budget and physical mechanism of the transition. Combining the non-pulsed X-ray and γ-ray fluxes measured here with previously published radio-to-UV data, we further construct a broadband spectral energy distribution of the PWN, which shows properties markedly different from those of the Crab Nebula.
Related
- Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula
- JWST observations of the planetary nebula NGC 6302 IV: PAH spectral characteristics, formation and evolution
- JWST observations of the planetary nebula NGC 6302 IV: PAH spectral characteristics, formation and evolution
- Origin of the high-energy spectral cutoff in gamma-ray pulsar halos
- Spectral energy-loss bump and γ-ray pulsar halos
BibTeX
@misc{zhang2026flux,
title = {{Flux Evolution of PSR B0540--69 and the Spectral Energy Distribution of its Pulsar Wind Nebula}},
author = {Juan Zhang and Xuezhi Liu and Junyang Zhang and Hanlong Peng and Mingyu Ge and Songzhan Chen and Shanshan Weng and Shijie Zheng and Shumei Jia and Chengkui Li and Haisheng Zhao and Ju Guan and Yong Chen and Liming Song and Fangjun Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.13182},
eprint = {2610.13182},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.13182},
}
RIS
TY - UNPB
TI - Flux Evolution of PSR B0540--69 and the Spectral Energy Distribution of its Pulsar Wind Nebula
AU - Juan Zhang
AU - Xuezhi Liu
AU - Junyang Zhang
AU - Hanlong Peng
AU - Mingyu Ge
AU - Songzhan Chen
AU - Shanshan Weng
AU - Shijie Zheng
AU - Shumei Jia
AU - Chengkui Li
AU - Haisheng Zhao
AU - Ju Guan
AU - Yong Chen
AU - Liming Song
AU - Fangjun Lu
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.13182
UR - https://arxiv.org/abs/2610.13182
AB - The young Crab-like pulsar PSR B0540--69, located in the Large Magellanic Cloud, underwent a spin-down rate transition (SRT) in 2011 December, after which its pulsar wind nebula (PWN) was reported to brighten up to 2018. In this work, we extend the study of its X-ray and γ-ray flux evolution through 2026 by combining observations from multiple X-ray instruments with data from the Fermi Large Area Telescope, thereby constructing a flux history of the PSR+PWN system spanning more than two decades. We find that the enhanced X-ray luminosity of the PSR+PWN system has persisted for more than 14 yr after the SRT, up to early 2026, whereas the pulsed X-ray flux remains unchanged across all epochs. This confirms that the brightening originates from the PWN. In the γ-ray band, neither the pulsed nor the non-pulsed flux shows any detectable long-term variation between 2008 and 2025. Together, these results imply that the additional spin-down energy released at the SRT has been continuously injected into the PWN over decades, placing strong constraints on the energy budget and physical mechanism of the transition. Combining the non-pulsed X-ray and γ-ray fluxes measured here with previously published radio-to-UV data, we further construct a broadband spectral energy distribution of the PWN, which shows properties markedly different from those of the Crab Nebula.
ER -