White Dwarf Natal Kicks as Velocity-Space Random Walks. II. Binary Stellar Evolution and Observational Kick Constraints
Abstract
Wide binaries containing white dwarfs (WDs) provide a pathway to exploring post-main-sequence (MS) natal kicks associated with asymmetric mass loss. In this work, we develop a binary population synthesis model that involves episodic mass loss and velocity kicks during the thermally-pulsing asymptotic-giant-branch (TP-AGB) phase of stellar evolution, when mass loss is expected to be most significant. We compare our synthesized populations against the Gaia DR2 and DR3 data for wide WD-MS and WD-WD binaries, varying the number, strength, and directionality of TP-AGB kicks. We find that the observed separation distribution can constrain the kick strength, but it alone is insufficient to also constrain the kick number and dimensionality. We therefore additionally constrain our models using the observed eccentricity distributions. Models where mass loss induces a random walk in the star's velocity are most consistent with observed eccentricity constraints for WD-MS binaries. No models are found to agree with the WD-WD eccentricity constraint. Our results suggest that at least 10 randomly directed kicks take place during the TP-AGB phase, leading to a cumulative root-mean-square kick velocity of approximately 0.7 km/s. These findings constrain the nature of WD natal kicks, connecting the orbital distributions of evolved wide binaries to asymmetric mass loss during the final stages of stellar evolution.
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BibTeX
@misc{pham2026white,
title = {{White Dwarf Natal Kicks as Velocity-Space Random Walks. II. Binary Stellar Evolution and Observational Kick Constraints}},
author = {Dang Pham and Stephen Majeski and Taeho Ryu and Gabriel Tomassini and Andrea Chiavassa},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.20941},
eprint = {2609.20941},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.20941},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - White Dwarf Natal Kicks as Velocity-Space Random Walks. II. Binary Stellar Evolution and Observational Kick Constraints
AU - Dang Pham
AU - Stephen Majeski
AU - Taeho Ryu
AU - Gabriel Tomassini
AU - Andrea Chiavassa
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.20941
UR - https://arxiv.org/abs/2609.20941
AB - Wide binaries containing white dwarfs (WDs) provide a pathway to exploring post-main-sequence (MS) natal kicks associated with asymmetric mass loss. In this work, we develop a binary population synthesis model that involves episodic mass loss and velocity kicks during the thermally-pulsing asymptotic-giant-branch (TP-AGB) phase of stellar evolution, when mass loss is expected to be most significant. We compare our synthesized populations against the Gaia DR2 and DR3 data for wide WD-MS and WD-WD binaries, varying the number, strength, and directionality of TP-AGB kicks. We find that the observed separation distribution can constrain the kick strength, but it alone is insufficient to also constrain the kick number and dimensionality. We therefore additionally constrain our models using the observed eccentricity distributions. Models where mass loss induces a random walk in the star's velocity are most consistent with observed eccentricity constraints for WD-MS binaries. No models are found to agree with the WD-WD eccentricity constraint. Our results suggest that at least 10 randomly directed kicks take place during the TP-AGB phase, leading to a cumulative root-mean-square kick velocity of approximately 0.7 km/s. These findings constrain the nature of WD natal kicks, connecting the orbital distributions of evolved wide binaries to asymmetric mass loss during the final stages of stellar evolution.
ER -