论文标题
双白矮人分离分布的差距是由公共 - 嵌入式演化引起的：盖亚的星体证据
A gap in the double white dwarf separation distribution caused by the common-envelope evolution: astrometric evidence from Gaia
论文作者
论文摘要
未解决的二进制的光中心的轨迹与质量中心的轨迹不同。因此，二进制引起的恒星质心摇摆可以被检测为单-Star星体模型的拟合度中的过量。我们在{\ it gaia}早期数据版本3中使用减少的$χ^2 $，以检测可能未解决的双白色矮人（DWDS）。使用基于视差的距离，我们将减少$χ^2 $的过量转换为质心摇摆$ΔA$的幅度，该质量与二进制分离$ a $成正比。测量的$ΔA$分布下降到更大的摇摆幅度，并显示出大约$ΔA\约0.2 $的休息时间。分配的积分产生的DWD分数为$ 6.5 \ pm 3.7 $ 3.7 $ 3.7 $ $ 0.01 <a（\ text {au}）<2 $。使用银河系DWD的合成模型，我们证明了$ΔA$分布中的断裂对应于DWD分离分布中深间隙的一侧，约为$ a \ a \ 1 $ au。由于（至少一个）共同的包络阶段（重塑原始的分离分布，清除缝隙并创建了$ a \ au \ au \ au \ $ΔA<0.01 $），因此具有分离型DWD少于几个AU缩小的收缩率少于几个AU收缩。我们的模型重现了观察到的$ΔA$分布及其归一化的整体形状，但是超出破裂之外的DWD的预测下降比数据陡峭。
The trajectory of the center of light of an unresolved binary is different from that of its center of mass. Binary-induced stellar centroid wobbling can therefore be detected as an excess in the goodness-of-fit of the single-star astrometric model. We use reduced $χ^2$ of the astrometric fit in the {\it Gaia} Early Data Release 3 to detect the likely unresolved double white dwarfs (DWDs). Using parallax-based distances we convert the excess of reduced $χ^2$ into the amplitude of the centroid wobble $δa$, which is proportional to the binary separation $a$. The measured $δa$ distribution drops towards larger wobble amplitudes and shows a break around $δa \approx 0.2$ where it steepens. The integral of the distribution yields DWD fraction of $6.5 \pm 3.7$ per cent in the range $0.01 < a (\text{au}) < 2$. Using synthetic models of the Galactic DWDs we demonstrate that the break in the $δa$ distribution corresponds to one side of a deep gap in the DWD separation distribution at around $a\approx 1$ au. Model DWDs with separations less than several au shrink dramatically due to (al least one) common envelope phase, reshaping the original separation distribution, clearing a gap and creating a pile-up of systems with $a\approx 0.01$ au and $δa < 0.01$. Our models reproduce the overall shape of the observed $δa$ distribution and its normalisation, however the predicted drop in the numbers of DWDs beyond the break is steeper than in the data.
