EAPSI: Multiband Photometry Simulations to Distinguish Transiting Exoplanets from False Positives

这项研究将与日本系外行星科学领域的两位专家Motohide Tamura教授和助理教授Norio Narita合作进行。 两人都是东京大学天文系的科学家。成田教授和该项目的首席研究员（PI）是凌日系外行星调查卫星（TESS）科学团队的成员。TESS是美国宇航局的一项使命，将于2018年3月发射，用于搜索大部分天空中相对较近的凌日系外行星。在近期技术的帮助下，人类找到可能承载生命的系外行星的最佳机会在于检查超级地球行星的大气层，这些行星在其可居住区内相对较冷，质量较低的M矮星宿主恒星（Charbonneau德明，2007）。模拟预测，TESS将在其为期两年的主要使命中探测到大约1,700颗系外行星，其中三分之一的行星半径将小于地球的两倍，其中四分之三的超级地球绕M矮星运行（Sullivan et al.，2015年）。然而，模拟也表明，TESS将检测到超过1,000个天体物理误报。因此，TESS的发现必须使用额外的仪器和/或技术来验证是否来自真实的系外行星。日本人提出，他们最近开发的用于研究凌日系外行星大气层的多色同步相机（麝香）在冈山天文台被用作区分TESS发现的系外行星与误报的工具。该研究项目的目的是使用麝香模拟TESS探测的后续观测，从而揭示哪些行星候选者可以使用麝香有效验证，哪些必须使用其他技术验证。这种理解将使天文学家能够更好地优先考虑和优化TESS探测的后续验证，这反过来将导致最佳利用宝贵的空间资产，如詹姆斯韦伯太空望远镜（JWST）。凌日系外行星可以通过确定接收到的恒星光的波长/颜色依赖性与天体物理学的误报区分开来，凌日系外行星在不同的带通中观察时基本上是消色差的。因此，TESS的发现可以通过确定在地球上探测到的恒星光的波长/颜色依赖性来验证为真正的凌日系外行星。PI将通过开发模拟麝香仪器性能的软件代码来模拟TESS检测的MuSCAT观测（Narita等人，2015），并考虑了所有重要的噪声源，例如光子噪声、天空背景噪声和闪烁噪声。TESS行星候选者在参数方面会有很大的差异，比如宿主星星的温度和亮度，或者行星的大小和轨道距离。为了提供对可能的候选行星的现实估计，PI将使用Sullivan等人（2015）发表的模拟TESS检测到的系外行星数据库，以及TESS检测到的模拟假阳性（TESS科学团队可用）。 该奖项，根据东亚和太平洋夏季研究所计划，支持美国研究生的夏季研究，并由NSF和日本科学促进协会（JSPS）共同资助。

This research will be conducted in collaboration with two Japanese experts in the field of exoplanetary science, Professor Motohide Tamura and Assistant Professor Norio Narita. Both are scientists at the University of Tokyo, Department of Astronomy. Professor Narita and this project's principal investigator (PI) are members of the Transiting Exoplanet Survey Satellite (TESS) Science Team. TESS is a NASA mission that will launch in March 2018 to search most of the sky for relatively nearby transiting exoplanets. With near-term technology, mankind's best chance of finding exoplanets that could host life lies in examining the atmospheres of super-Earth planets transiting relatively cool, low-mass M-dwarf host stars within their habitable zones (Charbonneau & Deming, 2007). Simulations predict that TESS will detect about 1,700 exoplanets over its two-year primary mission, and that one-third of those planets will have radii less than twice that of Earth, with three-quarters of these super-Earths orbiting M-dwarfs (Sullivan et al., 2015). However, simulations also show that TESS will detect over 1,000 astrophysical false positives. Thus, TESS discoveries must be validated as originating from real exoplanets using additional instruments and/or techniques. The Japanese have proposed that their recently-developed Multicolor Simultaneous Camera for Studying Atmospheres of Transiting Exoplanets (MuSCAT) at Okayama Observatory be used as a tool to distinguish TESS-discovered exoplanets from false positives. The purpose of this research project is to simulate follow-up observations of TESS detections using MuSCAT, thereby revealing which planet candidates can be efficiently validated using MUSCAT, and which must be validated using other techniques. This understanding will allow astronomers to better prioritize and optimize follow-up validations of TESS detections, which in turn will lead to optimal use of valuable space assets, such as the James Webb Space Telescope (JWST). Transiting exoplanets can be distinguished from astrophysical false positives by determining the wavelength/color-dependence of the amount of stellar light received transiting exoplanets are largely achromatic when observed in different bandpasses. Thus, TESS discoveries can be validated as true transiting exoplanets by determining the wavelength/color-dependence of the amount of stellar light detected on Earth. The PI will simulate MuSCAT observations of TESS detections by developing a software code that models the performance of the MuSCAT instrument (Narita et al., 2015) and accounts for all significant noise sources, such as photon noise, sky background noise, and scintillation noise. TESS planet candidates will vary tremendously in terms of parameters such as the temperature and brightness of the host star, or size and orbital distance of the planet. To provide a realistic estimate of likely candidate planets, the PI will use the database of simulated TESS-detected exoplanets published by Sullivan et al. (2015), as well as simulated false positives detected by TESS (available to the TESS Science team). This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science (JSPS).