arXiv 2202.041992022-02-08astro-ph.SRastro-ph.GA

$Gaia$的粒子数合成拟合在100 pc以内分辨的白矮星双星粒子数

A population synthesis fitting of the $Gaia$ resolved white dwarf binary population within 100 pc

S. Torres, P. Canals, F. M. Jiménez-Esteban, A. Rebassa-Mansergas, E. Solano

备注：: 14 pages, 8 figures, 5 tables, accepted for publication in MNRAS
DOI：: 10.1093/mnras/stac374

摘要：

$Gaia$任务提供了关于我们银河系白矮星数量的前所未有的丰富信息。特别是，我们的研究表明，来自太阳的高达100pc的样本可以被认为是实际上完整的。这一事实使我们能够通过共动对的识别来估计双简并星（$1.18\pm 0.10$ \%）和白矮星加主序星（$6.31\pm0.23$ \%）在所有白矮星中的精确比例。借助于详细的人口合成代码，我们能够再现合成白矮星人口与几乎相同的分数作为观察到的，从而获得有价值的信息的二进制部分，$f_{\rm b}$，初始质量比分布，$n(q)$，和初始分离分布，$f(a)$，以及其他参数。我们的最佳拟合模型在$f(a)\propto a^{-1}$、$n(q)\propto q^{n_q}$、$n_q=-1.13^{+0.12}_{-0.10}$和$f_{\rm b}=0.32\pm 0.02$的$1σ$置信水平内实现。由这个模型产生的部分白矮星合并是$9\sim16\%$，取决于共同的包络处理。作为我们的模型的子产品，我们发现周围的PDMATHAMBMY的白矮星人口是未解决的双简并，只有PDMATHAMBMZ的所有白矮星包含一个氦核心。最后，在白矮星的形成过程中，只有一个温和的踢似乎是必要的拟合观测到的天空分离的双简并系统。

英文摘要：

The $Gaia$ mission has provided an unprecedented wealth of information about the white dwarf population of our Galaxy. In particular, our studies show that the sample up to 100\,pc from the Sun can be considered as practically complete. This fact allows us to estimate a precise fraction of double-degenerate ($1.18\pm 0.10$\%) and white dwarf plus main-sequence stars ($6.31\pm0.23$\%) among all white dwarfs through comoving pairs identification. With the aid of a detailed population synthesis code we are able to reproduce synthetic white dwarf populations with nearly identical fractions as the observed ones, thus obtaining valuable information about the binary fraction, $f_{\rm b}$, initial mass ratio distribution, $n(q)$, and initial separation distribution, $f(a)$, among other parameters. Our best-fit model is achieved within a $1σ$ confidence level for $f(a)\propto a^{-1}$, $n(q)\propto q^{n_q}$, with $n_q=-1.13^{+0.12}_{-0.10}$ and $f_{\rm b}=0.32\pm 0.02$. The fraction of white dwarf mergers generated by this model is $9\sim16\%$, depending on the common-envelope treatment. As sub-products of our modelling we find that around $1\sim3\%$ of the white dwarf population are unresolved double-degenerates and that only $\sim1\%$ of all white dwarfs contain a He-core. Finally, only a mild kick during white dwarf formation seems to be necessary for fitting the observed sky separation of double-degenerate systems.

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