arXiv 1604.034442016-04-12astro-ph.EP

对LSST在测量近地物体群中的性能进行建模

Modeling the Performance of the LSST in Surveying the Near-Earth Object Population

Tommy Grav, Amy Mainzer, Tim Spahr

备注：: 11 page, 7 figures. Accepted for publication in Astronomical Journal
DOI：: 10.3847/0004-6256/151/6/172

摘要：

我们利用该项目目前的基线节奏，对LSST在近地天体方面的性能进行了详细的调查模拟。调查显示，如果项目能够可靠地生成位置和时间的链接集，（所谓的“轨迹片段”），其使用每晚对给定对象的两次检测，并且可以将这些轨迹片段链接到具有覆盖超过~12天弧长的最少3个轨迹片段的轨迹中，他们将能够在其预计的10年调查寿命内发现62%的大于140米的潜在危险小行星（PHAs）。如果该项目无法使用两个探测节奏实施一个管道，而不得不采用现有近地天体调查中更常用的四个探测节奏，则完整性将降至58%。当包括当前运行调查的估计性能时，假设这些将继续运行，直到LSST开始或之后，大于140 m的PHA的完整性分数对于基线节奏为73%，对于四个检测节奏为71%。该结果低于Ivezic等人（2007，2014）的估计值;但与Jones等人（2016）的估计值相当，后者显示完整性约为70$%。我们还表明，传统的方法，使用绝对星等H < 22等作为替代的人口直径大于140米的结果，在完整性值太高了~ 5%。我们的模拟利用了近地天体群物理和轨道特性的最新模型，以及LSST提供的模拟节奏和望远镜性能估计。我们进一步表明，虽然LSST或NEOCam等天基红外平台都无法单独完成对直径140米的近地天体的调查，但这些系统的组合可以在十年的观测后实现这一目标。

英文摘要：

We have performed a detailed survey simulation of the LSST performance with regards to near-Earth objects (NEOs) using the project's current baseline cadence. The survey shows that if the project is able to reliably generate linked sets of positions and times (a so-called "tracklet") using two detections of a given object per night and can link these tracklets into a track with a minimum of 3 tracklets covering more than a ~12 day length-of-arc, they would be able to discover 62% of the potentially hazardous asteroids (PHAs) larger than 140 m in its projected 10 year survey lifetime. This completeness would be reduced to 58% if the project is unable to implement a pipeline using the two detection cadence and has to adopt the four detection cadence more commonly used by existing NEO surveys. When including the estimated performance from the current operating surveys, assuming these would continue running until the start of LSST and perhaps beyond, the completeness fraction for PHAs larger than 140m would be 73% for the baseline cadence and 71% for the four detection cadence. This result is a lower than the estimate of Ivezic et al. (2007,2014); however it is comparable to that of Jones et al. (2016) who show completeness ~70$%. We also show that the traditional method of using absolute magnitude H < 22 mag as a proxy for the population with diameters larger than 140m results in completeness values that are too high by ~5%. Our simulation makes use of the most recent models of the physical and orbital properties of the NEO populations, as well as simulated cadences and telescope performance estimates provided by LSST. We further show that while neither LSST nor a space-based IR platform like NEOCam individually can complete the survey for 140m diameter NEOs, the combination of these systems can achieve that goal after a decade of observation.

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