论文标题
KMT-2019-BLG-2073：$θ_\ rm e <10 \rmμas$的第四个自由浮动行星候选者
KMT-2019-BLG-2073: Fourth Free-Floating-Planet Candidate with $θ_\rm E < 10 \rmμas$
论文作者
论文摘要
我们分析了非常简短的爱因斯坦时间尺度（$ t_ \ rm e \ simeq 7 \，{\ rm hr} $）事件kmt-2019-blg-2073。利用巨大源产生的明显有限源效应，我们测量了爱因斯坦半径$θ_\ rm e \ rm e \ simeq 4.8 \，\ rmμas$，因此推断质量$ $ $ m = 59 \ \，m_ \ oplus（m_ \ oplus） $π_\ rm {rel} $是镜头源相对视差。我们没有发现这个行星质量物体的主机的显着证据，尽管可以在足够宽的分离处存在。如果是这样，大约10年后将可以检测到。这是具有测得的爱因斯坦半径$θ_\ rm {e} <10 \，\ rmμas$的第四个孤立的微丝片，我们认为这是“可能自由浮动行星（FFP）”候选者的有用阈值。我们概述了一种新的方法，用于构建巨型巨星有限源/点透镜（FSPL）事件的均匀样本，其中可以对FFP候选者的子样本进行统计分析。我们使用2019 kmtnet数据说明了这种方法，并表明两个FFP候选人与其他11个FSPL事件之间存在大型$θ_\ rm {e} $差距。我们认为，与基于简短$ t_ \ rm {e} $识别候选人的传统方法相比，在$θ_\ rm {e} $中选择的样本中更加可识别这种敏锐的功能。
We analyze the very short Einstein timescale ($t_\rm E \simeq 7\,{\rm hr}$) event KMT-2019-BLG-2073. Making use of the pronounced finite-source effects generated by the clump-giant source, we measure the Einstein radius $θ_\rm E \simeq 4.8\,\rm μas$, and so infer a mass $M = 59\,M_\oplus (π_\rm{rel}/16 \,\rm μas)^{-1}$, where $π_\rm{rel}$ is the lens-source relative parallax. We find no significant evidence for a host of this planetary mass object, though one could be present at sufficiently wide separation. If so, it would be detectable after about 10 years. This is the fourth isolated microlens with a measured Einstein radius $θ_\rm{E}<10\,\rm μas$, which we argue is a useful threshold for a "likely free-floating planet (FFP)" candidate. We outline a new approach to constructing a homogeneous sample of giant-star finite-source/point-lens (FSPL) events, within which the subsample of FFP candidates can be statistically analyzed. We illustrate this approach using 2019 KMTNet data and show that there is a large $θ_\rm{E}$ gap between the two FFP candidates and the 11 other FSPL events. We argue that such sharp features are more identifiable in a sample selected on $θ_\rm{E}$ compared to the traditional approach of identifying candidates based on short $t_\rm{E}$.
