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arXiv 1708.09601astro-ph.SR
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后周期极小激变变星的空间密度

The Space Density of Post-Period Minimum Cataclysmic Variables

J. V. Hernandez Santisteban, C. Knigge, M. L. Pretorius, M. Sullivan, B. Warner

摘要:

双星演化理论预测,星系中激变变星(CV)的数量主要是由与亚恒星伴星吸积的白矮星组成。为了检验这些预测,有必要确定这些系统,如果吸积的特征变得太弱而无法检测到,这可能很困难。识别这种“死”简历的唯一机会是利用它们的接近二进制性质。因此,我们在斯隆数字巡天(SDSS)条纹82区域寻找明显孤立的白矮星,这些白矮星经历了暗伴星的食。我们在SDSS或帕洛玛瞬时工厂数据集中,在条纹82内通过光度测量选择的2264颗白矮星候选者的样本中,都没有发现这样的日食。这个空结果允许我们为死CV的空间密度$ρ_0$设置一个严格的上限。为了确定这个极限,我们使用了蒙特卡罗模拟,通过银河CV分布的简单模型来折叠我们的选择标准。假设一个$T_{WD}=7,500$ K,那么死亡CV的空间密度的2 $σ$极限是$ρ_0 \lesssim 2 \times 10^{-5}$ pc $^{-3}$,其中$T_{WD}$是这种系统中白矮星的典型有效温度。

英文摘要:

Binary evolution theory predicts that accreting white dwarfs with sub-stellar companions dominate the Galactic population of cataclysmic variables (CVs). In order to test these predictions, it is necessary to identify these systems, which may be difficult if the signatures of accretion become too weak to be detected. The only chance to identify such "dead" CVs is by exploiting their close binary nature. We have therefore searched the Sloan Digital Sky Survey (SDSS) Stripe 82 area for apparently isolated white dwarfs that undergo eclipses by a dark companion. We found no such eclipses in either the SDSS or Palomar Transient Factory data sets among our sample of 2264 photometrically selected white dwarf candidates within Stripe 82. This null result allows us to set a firm upper limit on the space density, $ρ_0$, of dead CVs. In order to determine this limit, we have used Monte-Carlo simulations to fold our selection criteria through a simple model of the Galactic CV distribution. Assuming a $T_{WD}=7,500$ K, the resulting 2$σ$ limit on the space density of dead CVs is $ρ_0 \lesssim 2 \times 10^{-5}$ pc$^{-3}$, where $T_{WD}$ is the typical effective temperature of the white dwarf in such systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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