Formation and Detectability of PSR J0653+0443-like Extremely Eccentric Binary Neutron Stars in the Milky Way
Abstract
Recently, the Five-hundred-meter-Aperture-Spherical-radio-Telescope (FAST) Galactic Plane Pulsar Snapshot (GPPS) survey discovers an extraordinary binary neutron star (BNS) system, PSR J0653+0443, possessing the highest known orbital eccentricity (e≈0.992) among Galactic BNSs (Yang et al., 2026), which provides a unique probe into the formation and evolution of BNSs. In this Letter, we perform compact binary population synthesis calculations with self-consistent neutron star spin evolution to model extremely eccentric BNS population detectable by the FAST GPPS survey, explicitly incorporating observational selection effects. We find that BNSs with e>0.99 constitute only ∼0.6% of the detectable population, with an expected detection number of λGPPS≈0.31 over the full planned footprint. Thus, although rare, systems as eccentric as PSR J0653+0443 are compatible with standard binary evolution. We further demonstrate that extremely eccentric BNSs arise preferentially from core-collapse supernovae, whereas imposing P≲0.1 s select older, more frequently recycled systems, which naturally reproduce the observed properties of PSR J0653+0443. We further predict that the completed GPPS sample has a ∼15% chance of finding another e>0.99 BNS, but a much higher ∼88% chance for e>0.90 systems. By contrast, future facilities are expected to enlarge the detectable highly eccentric BNS population, with SKA potentially detecting PSR J0653+0443-like systems and sub-mHz gravitational-wave detectors probing a larger population with e>0.9, enabling much more in-depth population-level constraints.
Related
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- A Massive and Eccentric Binary Millisecond Pulsar in the Globular Cluster M10
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BibTeX
@misc{chen2026formation,
title = {{Formation and Detectability of PSR J0653+0443-like Extremely Eccentric Binary Neutron Stars in the Milky Way}},
author = {Zhiwei Chen and Jihui Zhang and Youjun Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31583},
eprint = {2610.31583},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31583},
}
RIS
TY - UNPB
TI - Formation and Detectability of PSR J0653+0443-like Extremely Eccentric Binary Neutron Stars in the Milky Way
AU - Zhiwei Chen
AU - Jihui Zhang
AU - Youjun Lu
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31583
UR - https://arxiv.org/abs/2610.31583
AB - Recently, the Five-hundred-meter-Aperture-Spherical-radio-Telescope (FAST) Galactic Plane Pulsar Snapshot (GPPS) survey discovers an extraordinary binary neutron star (BNS) system, PSR J0653+0443, possessing the highest known orbital eccentricity (e≈0.992) among Galactic BNSs (Yang et al., 2026), which provides a unique probe into the formation and evolution of BNSs. In this Letter, we perform compact binary population synthesis calculations with self-consistent neutron star spin evolution to model extremely eccentric BNS population detectable by the FAST GPPS survey, explicitly incorporating observational selection effects. We find that BNSs with e>0.99 constitute only ∼0.6% of the detectable population, with an expected detection number of λ_GPPS≈0.31 over the full planned footprint. Thus, although rare, systems as eccentric as PSR J0653+0443 are compatible with standard binary evolution. We further demonstrate that extremely eccentric BNSs arise preferentially from core-collapse supernovae, whereas imposing P≲0.1 s select older, more frequently recycled systems, which naturally reproduce the observed properties of PSR J0653+0443. We further predict that the completed GPPS sample has a ∼15% chance of finding another e>0.99 BNS, but a much higher ∼88% chance for e>0.90 systems. By contrast, future facilities are expected to enlarge the detectable highly eccentric BNS population, with SKA potentially detecting PSR J0653+0443-like systems and sub-mHz gravitational-wave detectors probing a larger population with e>0.9, enabling much more in-depth population-level constraints.
ER -