The ELM Survey. VIII. Ninety-eight Double White Dwarf Binaries
The ELM Survey. VIII. Ninety-eight Double White Dwarf Binaries
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DOI：
10.3847/1538-4357/ab63cd
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发表时间：
2020-01
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影响因子：
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通讯作者：
Warren R. Brown;M. Kilic;A. Kosakowski;J. Andrews;C. Heinke;M. Agueros;F. Camilo;A. Gianninas
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作者：
Warren R. Brown;M. Kilic;A. Kosakowski;J. Andrews;C. Heinke;M. Agueros;F. Camilo;A. Gianninas
我们提出了98个分离的双白色矮星（WD）的最后一个样本中发现的极低质量（ELM）调查，光谱调查针对<0.3 M的氦芯WD完成的斯隆数字巡天足迹。在调查的过程中，我们观察到辅助的低质量WD候选者，如GD 278，我们显示它是一个P = 0.19天的双WD双星，以及候选者，结果是场蓝离散星/亚矮星A型恒星，亮度太高，因为它们的盖亚星系太大。在这里，我们定义了一个干净的ELM WD样本，它在我们的目标选择和星等范围15 <g 0 < 20 mag. The测量是一致的100%的ELM WD为0.0089 < P < 1.5天双WD双星，其中35%属于银河系晕。我们推断，这些主要是他+CO WD二进制的测量限制。所观察到的他+CO WD二进制的合并率超过了稳定的质量传递AM CVn二进制的形成率的一个因素为25，所以大多数的他+CO WD二进制必须经历不稳定的质量传递和合并。具有最短周期的系统，如J 0651 +2844，是可以用引力波和光进行研究的签名丽莎验证二进制。
We present the final sample of 98 detached double white dwarf (WD) binaries found in the Extremely Low Mass (ELM) Survey, a spectroscopic survey targeting <0.3 M⊙ He-core WDs completed in the Sloan Digital Sky Survey footprint. Over the course of the survey we observed ancillary low-mass WD candidates like GD 278, which we show is a P = 0.19 day double WD binary, as well as candidates that turn out to be field blue straggler/subdwarf A-type stars with luminosities too high to be WDs given their Gaia parallaxes. Here, we define a clean sample of ELM WDs that is complete within our target selection and magnitude range 15 < g0 < 20 mag. The measurements are consistent with 100% of ELM WDs being 0.0089 < P < 1.5 day double WD binaries, 35% of which belong to the Galactic halo. We infer that these are mostly He+CO WD binaries given the measurement constraints. The merger rate of the observed He+CO WD binaries exceeds the formation rate of stable mass-transfer AM CVn binaries by a factor of 25, and so the majority of He+CO WD binaries must experience unstable mass transfer and merge. The systems with the shortest periods, such as J0651+2844, are signature LISA verification binaries that can be studied with gravitational waves and light.