Discovery of γ-Ray Pulsations from the Extreme-Spin-Down Millisecond Pulsar PSR J0435+3233
Abstract
Motivated by the recent discovery of PSR~J0435+3233, a millisecond pulsar with an exceptionally large period derivative of Ṗ=4.9×10−17 s s−1 and a high spin-down luminosity of Ė=5.89×1037 erg s−1, we analyze ∼17~yr of observations obtained with the \textit{Fermi} Large Area Telescope for the pulsar. We identify the cataloged source 4FGL~J0435.5+3232, located only 0.01∘ from the radio timing position, as the γ-ray counterpart of PSR~J0435+3233. Using γ-ray events collected within the validity interval of the radio timing ephemeris, we detect its γ-ray pulsations at a ∼6.8σ confidence level. In this interval, the phase-resolved analysis shows that the pulsed emission is concentrated predominantly within the rotational-phase of ϕ∼0.44--$0.69$. We also derive its γ-ray luminosity of Lγ=6.26×1032 erg s−1, assuming a distance of 1.2~kpc and isotropic emission. This luminosity corresponds to an apparent γ-ray efficiency of ηγ∼1.1×10−5, revealing an exceptionally low γ-ray output despite the pulsar's young-pulsar-like rotational-energy budget. Our detection establishes PSR~J0435+3233 as a γ-ray MSP, and the striking combination of its high spin-down power and low apparent γ-ray efficiency provides a new probe of particle acceleration, radiation beaming, and viewing geometry in the magnetospheres of millisecond pulsars with extreme rotational properties.
Versions
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BibTeX
@misc{zhang2026discovery,
title = {{Discovery of $γ$-Ray Pulsations from the Extreme-Spin-Down Millisecond Pulsar PSR J0435+3233}},
author = {Mengqing Zhang and Shengbin Pei and Pengfei Zhang},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.16119},
eprint = {2607.16119},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.16119},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Discovery of γ-Ray Pulsations from the Extreme-Spin-Down Millisecond Pulsar PSR J0435+3233
AU - Mengqing Zhang
AU - Shengbin Pei
AU - Pengfei Zhang
PY - 2026
DA - 2026/07/17
PB - arXiv
DO - 10.48550/arxiv.2607.16119
UR - https://arxiv.org/abs/2607.16119
AB - Motivated by the recent discovery of PSR~J0435+3233, a millisecond pulsar with an exceptionally large period derivative of Ṗ=4.9×10^−17 s s^−1 and a high spin-down luminosity of Ė=5.89×10^37 erg s^−1, we analyze ∼17~yr of observations obtained with the \textit{Fermi} Large Area Telescope for the pulsar. We identify the cataloged source 4FGL~J0435.5+3232, located only 0.01^∘ from the radio timing position, as the γ-ray counterpart of PSR~J0435+3233. Using γ-ray events collected within the validity interval of the radio timing ephemeris, we detect its γ-ray pulsations at a ∼6.8σ confidence level. In this interval, the phase-resolved analysis shows that the pulsed emission is concentrated predominantly within the rotational-phase of ϕ∼0.44--$0.69$. We also derive its γ-ray luminosity of L_γ=6.26×10^32 erg s^−1, assuming a distance of 1.2~kpc and isotropic emission. This luminosity corresponds to an apparent γ-ray efficiency of η_γ∼1.1×10^−5, revealing an exceptionally low γ-ray output despite the pulsar's young-pulsar-like rotational-energy budget. Our detection establishes PSR~J0435+3233 as a γ-ray MSP, and the striking combination of its high spin-down power and low apparent γ-ray efficiency provides a new probe of particle acceleration, radiation beaming, and viewing geometry in the magnetospheres of millisecond pulsars with extreme rotational properties.
ER -