XMM-Newton Observation and Optical Monitoring of the Candidate Redback Millisecond Pulsar 1FGL J0523.5-2529
- 1Columbia University
Abstract
1FGL J0523.5−2529 is a Fermi selected redback millisecond pulsar candidate that exhibited luminous optical and X-ray flares in 2020–2021. We obtained a simultaneous X-ray and U -band observation with XMM-Newton in 2025, the first to cover the 16.5 hr orbit of 1FGL J0523.5−2529. The X-ray luminosity was in an intermediate state with a power-law photon spectral index of Γ = 1.53 ± 0.02. Apparent fluctuations were superposed on a broad, single-peaked modulation, the latter characteristic of intrabinary shock models in which the shock front is wrapped around the pulsar. The U -band light curve was dominated by ellipsoidal modulation of the nearly Roche-lobe-filling companion star, similar to that seen in ground-based optical photometry. We also used this effect in 10 yr of ATLAS monitoring to improve the precision of the orbital period to 0.6881366(19) days. Considering that searches for radio pulsations from 1FGL J0523.5−2529 at all orbital phases have been unsuccessful, it may be that the shocked wind usually surrounds the pulsar.
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BibTeX
@article{halpern2026xmmnewton,
title = {{XMM-Newton Observation and Optical Monitoring of the Candidate Redback Millisecond Pulsar 1FGL J0523.5-2529}},
author = {Jules P. Halpern and Slavko Bogdanov},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/ae9d6a},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9d6a},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - XMM-Newton Observation and Optical Monitoring of the Candidate Redback Millisecond Pulsar 1FGL J0523.5-2529
AU - Jules P. Halpern
AU - Slavko Bogdanov
PY - 2026
DA - 2026/10/01
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/ae9d6a
UR - https://iopscience.iop.org/article/10.3847/1538-4357/ae9d6a
AB - 1FGL J0523.5−2529 is a Fermi selected redback millisecond pulsar candidate that exhibited luminous optical and X-ray flares in 2020–2021. We obtained a simultaneous X-ray and U -band observation with XMM-Newton in 2025, the first to cover the 16.5 hr orbit of 1FGL J0523.5−2529. The X-ray luminosity was in an intermediate state with a power-law photon spectral index of Γ = 1.53 ± 0.02. Apparent fluctuations were superposed on a broad, single-peaked modulation, the latter characteristic of intrabinary shock models in which the shock front is wrapped around the pulsar. The U -band light curve was dominated by ellipsoidal modulation of the nearly Roche-lobe-filling companion star, similar to that seen in ground-based optical photometry. We also used this effect in 10 yr of ATLAS monitoring to improve the precision of the orbital period to 0.6881366(19) days. Considering that searches for radio pulsations from 1FGL J0523.5−2529 at all orbital phases have been unsuccessful, it may be that the shocked wind usually surrounds the pulsar.
SN - 0004-637X
SN - 1538-4357
ER -