疏散星团中逃逸的白矮星候选体

中文摘要 AI 辅助

观测显示疏散星团中的白矮星相对于理论预期明显不足，这表明很大一部分白矮星可能在形成后从其母星团逃逸。在这项工作中，我们通过追溯盖亚DR3目录中白矮星和星团的运动，对疏散星团中逃逸的白矮星候选体进行了系统搜索。我们识别出476颗候选白矮星，其运动学与从175个疏散星团之一逃逸一致。控制场蒙特卡罗测试得出污染率为87.6%±4.3%。鉴于此高污染率，我们通过确保每颗白矮星的总年龄与其宿主星团年龄一致来筛选候选体，从而建立了一个更可靠的109颗恒星的后续样本。被排除的年龄异常的候选体更可能是场闯入者或加速双星演化的产物。其中，低质量区域的场双星合并率明显高于预期，而高质量区域仍与双星种群合成预测大致一致。最后，将逃逸的白矮星与星团性质进行比较，绝对逃逸计数似乎受盖亚距离依赖性不完整性的限制。归一化逃逸率对星团年龄的依赖性很小，可能更倾向于形成时的白矮星损失而非逐渐蒸发，但与星团质量强烈负相关，可能是因为大质量星团更深的势阱保留了更多的白矮星。

英文摘要

Observations reveal a pronounced deficit of white dwarfs (WDs) in open clusters (OCs) relative to theoretical expectations, suggesting that a significant fraction of WDs may have escaped from their parent clusters after formation. In this work, we perform a systematic search for escaped WD candidates from OCs by back-tracing the motions of WDs and star clusters from Gaia DR3 catalogs. We identify 476 candidate WDs with kinematics consistent with having escaped from one of 175 OCs. A control-field Monte Carlo (MC) test yields a contamination rate of 87.6% +/- 4.3%. Given this high contamination rate, we filter the candidates by ensuring each WD's total age is consistent with its host cluster age, thereby establishing a more reliable follow-up sample of 109 stars. The excluded candidates with anomalous ages are more likely field interlopers or products of accelerated binary evolution. Among these, the low-mass regime exhibits a clear excess over expected field binary merger rates, whereas the high-mass regime remains broadly consistent with binary population synthesis predictions. Finally, comparing escaped WDs with cluster properties, absolute escape counts appear limited by Gaia's distance-dependent incompleteness. The normalized escape fraction shows little dependence on cluster age, possibly favouring WD loss near formation over gradual evaporation, but is strongly anticorrelated with cluster mass, plausibly because deeper potential wells of massive clusters retain more of their WDs.

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Accepted by ApJS