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位日本专家田村元hide教授和成田则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是美国宇航局的一项任务，将于2018年3月发射，用于搜索大部分天空中相对较近的过境系外行星。利用近期的技术，人类找到可能存在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域内运行相对较冷、低质量的m矮星宿主恒星（Charbonneau & Deming, 2007）。模拟预测，TESS将在其两年的主要任务中探测到大约1700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围绕m矮星运行（Sullivan et al., 2015）。然而，模拟也表明，TESS将探测到1000多个天体物理假阳性。因此，TESS的发现必须通过使用额外的仪器和/或技术来验证是否来自真正的系外行星。日本人提议将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的多色同步相机（MuSCAT）用作区分tess发现的系外行星与假阳性的工具。本研究项目的目的是模拟使用MuSCAT对TESS探测的后续观测，从而揭示哪些候选行星可以使用MuSCAT有效地验证，哪些必须使用其他技术进行验证。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，这反过来将导致宝贵的空间资产的最佳利用，例如詹姆斯韦伯太空望远镜（JWST）。通过确定接收到的恒星光的波长/颜色依赖性，可以将凌日系外行星与天体物理假阳性区分开来，在不同的波段观测时，凌日系外行星基本上是消色差的。因此，通过确定在地球上探测到的恒星光的波长/颜色依赖性，TESS的发现可以被验证为真正的凌日系外行星。PI将通过开发一个软件代码来模拟MuSCAT仪器的性能（Narita等人，2015年），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，来模拟TESS探测的MuSCAT观测。TESS候选行星的参数会有很大的不同，比如宿主恒星的温度和亮度，或者行星的大小和轨道距离。为了对可能的候选行星提供一个现实的估计，PI将使用Sullivan等人（2015）发表的模拟TESS探测到的系外行星数据库，以及TESS探测到的模拟假阳性（可供TESS科学团队使用）。该奖项由美国国家科学基金会和日本科学促进会（Japan Society for the Promotion of Science， JSPS）共同资助，隶属于东亚和太平洋暑期研究所项目，支持一名美国研究生进行暑期研究。

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).