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

这项研究将与系外行星科学领域的两名日本专家田村元藏教授和成田纪夫助理教授合作进行。两人都是东京大学天文学系的科学家。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)科学小组的成员。TESS是NASA的一项任务，将于2018年3月发射，在大部分天空中搜索相对较近的凌日系外行星。利用近期技术，人类找到可能拥有生命的系外行星的最好机会在于检查在其宜居带内凌日相对较冷、低质量的M矮星的超地行星的大气层(Charbonneau&Amp；Deming，2007)。模拟预测，TESS将在其两年的主要任务中探测到约1700颗系外行星，其中三分之一的行星的半径将不到地球的两倍，其中四分之三的超级地球绕着M矮星运行(Sullivan等人，2015年)。然而，模拟也表明，TESS将检测到超过1000个天体物理假阳性。因此，TESS的发现必须使用额外的仪器和/或技术来确认是否起源于真正的系外行星。日本人提议，他们最近在冈山天文台开发的用于研究凌日系外行星大气层的多色同步相机(Muscat)，可以作为区分TESS发现的系外行星与假阳性的工具。这项研究项目的目的是模拟使用马斯喀特对TESS探测的后续观测，从而揭示哪些候选行星可以使用马斯喀特有效地验证，哪些必须使用其他技术验证。这一认识将使天文学家能够更好地确定TESS探测的后续验证的优先顺序和优化，这反过来将导致对宝贵的空间资产的最佳利用，例如詹姆斯·韦伯空间望远镜(JWST)。通过确定凌日系外行星接收到的恒星光的波长/颜色依赖关系，可以将凌日系外行星与天体物理假阳性区分开来。因此，通过确定在地球上探测到的恒星光量的波长/颜色相关性，TESS的发现可以被证实是真正的凌日系外行星。PI将通过开发一个软件代码来模拟马斯喀特对TESS探测的观测，该软件代码模拟马斯喀特仪器的性能(Narita等人，2015)，并考虑所有重要的噪声源，如光子噪声、天空背景噪声和闪烁噪声。TESS候选行星在参数方面会有很大的不同，比如主星的温度和亮度，或者行星的大小和轨道距离。为了提供可能的候选行星的真实估计，PI将使用Sullivan等人发布的模拟TESS探测到的系外行星数据库。(2015)，以及TESS检测到的模拟假阳性(可供TESS科学团队使用)。该奖项根据东亚和太平洋夏季学院计划，支持一名美国研究生的暑期研究，由NSF和日本科学促进会(JSPS)联合资助。

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).