Probability of Detecting a Planetary Companion during a Microlensing Event
Probability of Detecting a Planetary Companion during a Microlensing Event
复制标题
在微透镜事件期间检测到行星伴星的概率
DOI：
10.1086/320562
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
S. Peale
中科院分区：
文献类型：
--
作者：
S. Peale
当行星与星星质量比q = 0.001时，在朝向银河系中心的微透镜事件期间，检测到透镜星星的行星伴星的平均概率在轨道半长轴接近1.5 Au时具有最大值超过10%撞击参数的均匀分布。这个峰值比Gould & Loeb在1992年获得的最大值17%稍低，但对于由事件探测效率确定的源透镜撞击参数分布，它被提高到20%以上。虽然这些概率，基于信噪比（S/N）的检测标准，是模型和假设依赖的，事实上，它们的变化在可预测的方式作为轨道半长轴的功能，但保持稳健的所有相关的银河系参数的合理变化意味着他们是真实的值的代表。此外，平均程序被仔细定义，它们决定了检测概率对银河系几个属性的依赖性。其他行星与星星质量比的概率可以通过q1/2的近似比例来估计。如果单镜头光变曲线的扰动在事件期间的某个时间超过2/（S/N），则假设行星是可检测的，其中可以理解的是，在扰动期间至少需要20个连续的测光点来确认检测。S/N是放大源的瞬时值。此外，2米望远镜与60秒的积分在I波段与高时间分辨率测光整个持续时间的一个正在进行的事件被假定。概率是作为行星轨道半长轴a的函数导出的，其中峰值概率发生在a近似为透镜沿着视线分布的平均爱因斯坦环半径的地方。对于0.6 μ a/10 Au，概率仍然显著。探测概率对透镜质量函数、经消光修正的源星光度函数、源-透镜碰撞参数分布和源视线的依赖性也被确定，并且概率在行星在透镜平面上的投影位置分布、透镜质量函数、碰撞参数分布、在透镜和源沿着视线的分布上，以及在针对源距离和消光而调整的源的I波段光度函数上。特定撞击参数和特定源I量级的概率，但对其余退化参数取平均值，也可从分析中得出。在后一种情况下，指示从来自特定事件的经验数据中提取作为特定q的a的函数的概率。
The averaged probability of detecting a planetary companion of a lensing star during a microlensing event toward the Galactic center when the planet to star mass ratio q = 0.001 is shown to have a maximum exceeding 10% at an orbit semimajor axis near 1.5 AU for a uniform distribution of impact parameters. This peak value is somewhat lower than the maximum of 17% obtained by Gould & Loeb in 1992, but it is raised to more than 20% for a distribution of source-lens impact parameters that is determined by the efficiency of event detection. Although these probabilities, based on a signal-to-noise ratio (S/N) detection criterion, are model and assumption dependent, the fact that they change in predictable ways as functions of the orbit semimajor axes but remain robust for plausible variations of all the relevant Galactic parameters implies that they are representative of real values. In addition, the averaging procedures are carefully defined, and they determine the dependence of the detection probabilities on several properties of the Galaxy. The probabilities for other planet to star mass ratios can be estimated from an approximate scaling of q1/2. A planet is assumed detectable if the perturbation of the single-lens light curve exceeds 2/(S/N) sometime during the event, where it is understood that at least 20 consecutive photometric points during the perturbation are necessary to confirm the detection. S/N is the instantaneous value for the amplified source. In addition, 2 m telescopes with 60 s integrations in I band with high time resolution photometry throughout the duration of an ongoing event are assumed. The probabilities are derived as a function of semimajor axis a of the planetary orbit, where the peak probability occurs where a is approximately the mean Einstein ring radius of the distribution of lenses along the line of sight. The probabilities remain significant for 0.6 ≲ a ≲ 10 AU. Dependence of the detection probabilities on the lens mass function, luminosity function of the source stars as modified by extinction, distribution of source-lens impact parameters, and the line of sight to the source are also determined, and the probabilities are averaged over the distribution of the projected position of the planet onto the lens plane, over the lens mass function, over the distribution of impact parameters, over the distribution of lens and sources along the line of sight, and over the I-band luminosity function of the sources adjusted for the source distance and extinction. The probability for a particular impact parameter and particular source I magnitude but averaged over remaining degenerate parameters also follows from the analysis. In the latter case, the extraction of the probability as a function of a for a particular q from the empirical data from a particular event is indicated.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell