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Main Authors: Schiebelbein-Zwack, Aryanna, van Son, L. A. C, Fishbach, Maya, Farr, Will M.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.07393
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author Schiebelbein-Zwack, Aryanna
van Son, L. A. C
Fishbach, Maya
Farr, Will M.
author_facet Schiebelbein-Zwack, Aryanna
van Son, L. A. C
Fishbach, Maya
Farr, Will M.
contents The mass distribution of neutron stars encodes information about their formation and binary evolution. We compare the masses of two distinct populations: I) the recently identified Gaia neutron stars in wide orbits with solar-like companions and, II) the assumed first-born recycled pulsar in Galactic double neutron star systems. Naively, one would expect their masses to differ due to both the presumed differences in their evolutionary histories, as well as astrophysical selection effects that can filter out configurations that would merge or be disrupted. Yet, we find that their mass distributions are strikingly similar. Using a two-component Gaussian model, we find that both populations exhibit a narrow component centred near $1.3 \text{ M}_\odot$, accompanied by a broader, higher-mass component that extends the distribution toward larger masses. The highest density regions of their fitted parameter posteriors coincide by over 91.6%. Statistical tests further confirm the agreement between these distributions with a Jensen-Shannon divergence $JS < 0.08$ and an earth mover's distance of $W <0.063 \text{ M}_\odot$ at 90% credibility. This finding seems to imply that both mass functions reflect the natal mass distribution of first-born neutron stars in binary systems, supporting the hypothesis that neutron stars can be born with high masses. Consequently and perhaps surprisingly, binary evolutionary processes need not impart features on the NS mass distribution.
format Preprint
id arxiv_https___arxiv_org_abs_2511_07393
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Surprisingly Similar: The Mass Function of Gaia Neutron Stars and First-Born Double Neutron Stars
Schiebelbein-Zwack, Aryanna
van Son, L. A. C
Fishbach, Maya
Farr, Will M.
Solar and Stellar Astrophysics
The mass distribution of neutron stars encodes information about their formation and binary evolution. We compare the masses of two distinct populations: I) the recently identified Gaia neutron stars in wide orbits with solar-like companions and, II) the assumed first-born recycled pulsar in Galactic double neutron star systems. Naively, one would expect their masses to differ due to both the presumed differences in their evolutionary histories, as well as astrophysical selection effects that can filter out configurations that would merge or be disrupted. Yet, we find that their mass distributions are strikingly similar. Using a two-component Gaussian model, we find that both populations exhibit a narrow component centred near $1.3 \text{ M}_\odot$, accompanied by a broader, higher-mass component that extends the distribution toward larger masses. The highest density regions of their fitted parameter posteriors coincide by over 91.6%. Statistical tests further confirm the agreement between these distributions with a Jensen-Shannon divergence $JS < 0.08$ and an earth mover's distance of $W <0.063 \text{ M}_\odot$ at 90% credibility. This finding seems to imply that both mass functions reflect the natal mass distribution of first-born neutron stars in binary systems, supporting the hypothesis that neutron stars can be born with high masses. Consequently and perhaps surprisingly, binary evolutionary processes need not impart features on the NS mass distribution.
title Surprisingly Similar: The Mass Function of Gaia Neutron Stars and First-Born Double Neutron Stars
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2511.07393