The exoplanet microlensing survey by the proposed WFIRST Observatory

Barry, Richard; Kruk, J.; Anderson, Jay; Beaulieu, J. P.; Bennett, D. P.; Catanzarite, J.; Cheng, E. S.; Gaudi, Scott; Gehrels, N.; Kane, Stephen R.; Lunine, Jonathan I.; Sumi, T.; Tanner, Angelle; Traub, Wesley A.

doi:10.1117/12.898574

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…This work relies on extrapolation from Kepler occurrence rates for shorter period planets, but ice giants in the habitable zone and beyond could be a significant source of false positives for EEC detection. WFIRST could detect hundreds of wide-orbit planets through its microlensing survey, some with masses lower than the Earth (Barry et al 2011;Penny et al 2019). PLATO will also detect a number of transiting planets on orbits as wide as the Earth's (ESA 2017).…”

Section: What Is the Period Distribution For Planets On Wide Orbits?mentioning

confidence: 99%

Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification

Bixel

Apai

2019

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Future space telescopes may be able to directly image ∼10 -100 planets with sizes and orbits consistent with habitable surface conditions ("exo-Earth candidates" or EECs), but observers will face difficulty in distinguishing these from the potentially hundreds of non-habitable "false positives" which will also be detected. To maximize the efficiency of follow-up observations, a prioritization scheme must be developed to determine which planets are most likely to be EECs. In this paper, we present a Bayesian method for estimating the likelihood that any directly imaged extrasolar planet is a true exo-Earth candidate by interpreting the planet's apparent magnitude and separation in light of existing exoplanet statistics. As a specific application of this general framework, we use published estimates of the discovery yield of future space-based direct imaging mission concepts to conduct "mock surveys" in which we compute the likelihood that each detected planet is an EEC. We find that it will be difficult to determine which planets are EECs with > 50% confidence using single-band photometry immediately upon their detection. The best way to reduce this ambiguity would be to constrain the planet's orbit by revisiting the system multiple times or through a radial velocity precursor survey. Astrometric or radial velocity constraints on the planet's mass would offer a lesser benefit. Finally, we show that a Bayesian approach to prioritizing targets would improve the follow-up efficiency of a direct imaging survey versus a blind approach using the same data. For example, the prioritized approach could reduce the amount of integration time required for the spectral detection (or rejection) of water absorption in most EECs by a factor of two.

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Section: What Is the Period Distribution For Planets On Wide Orbits?mentioning

confidence: 99%

Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification

Bixel

Apai

2019

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“…Euclid provides a 0.55 deg 2 field of view (FOV) with a 1.2-m mirror, whereas WFIRST would provide a 0.28 deg 2 FOV with a 2.4-m mirror, as compared to a 0.17 deg 2 FOV with a 3.6-m mirror for GravityCam with CMOS detectors on the ESO NTT. The microlensing campaigns with the space telescopes would be restricted to observing windows lasting one or two months only, substantially reducing the planet detection capabilities, given that the median timescale of microlensing events is around a month (Penny et al 2013;Barry et al 2011).…”

Section: The Gravitycam Microlensing Surveymentioning

confidence: 99%

GravityCam: Wide-field high-resolution high-cadence imaging surveys in the visible from the ground

Mackay

Dominik

Steele

et al. 2018

Publ. Astron. Soc. Aust.

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GravityCam is a new concept of ground-based imaging instrument capable of delivering significantly sharper images from the ground than is normally possible without adaptive optics. Advances in optical and near infrared imaging technologies allow images to be acquired at high speed without significant noise penalty. Aligning these images before they are combined can yield a 3-5 fold improvement in image resolution. By using arrays of such detectors, survey fields may be as wide as the telescope optics allows. We describe the instrument and detail its application to accelerate greatly the rate of detection of Earth size planets by gravitational microlensing. GravityCam will improve substantially the quality of weak shear studies of dark matter distribution in distant clusters of galaxies. An extensive microlensing survey will also provide a vast dataset for asteroseismology studies, and GravityCam promises to generate a unique data set on the population of the Kuiper belt and possibly the Oort cloud.

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“…Therefore, a dedicated space telescope that can achieve diffraction-limited, high photometric precision observations is required (Bennett and Rhie 2002;Bennett 2008). Such aspirations may eventually be realized in the form of the Euclid mission , the Wide Field InfraRed Space Telescope (WFIRST) (Barry et al 2011) mission, or the NEW-WFIRST mission (Dressler et al 2012), which should be capable of detecting planets as small as Mars (∼0.1 M ⊕ ). In particular, two 2.4 m telescopes, built by the US National Reconnaissance Office and transfered to NASA offer diffraction limited imaging of 0.16 arc-seconds at λ = 1.6 µm and might triple the yield of Mars-size planets compared to the design reference mission of WFIRST (Dressler et al 2012).…”

Section: Microlensingmentioning

confidence: 99%

Below One Earth: The Detection, Formation, and Properties of Subterrestrial Worlds

et al. 2013

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The Solar System includes two planets -Mercury and Mars -significantly less massive than Earth, and all evidence indicates that planets of similar size orbit many stars. In fact, one of the first exoplanets to be discovered is a lunar-mass planet around a millisecond pulsar. Novel classes of exoplanets have inspired new ideas about planet formation and evolution, and these "sub-Earths" should be no exception: they include planets with masses between Mars and Venus for which there are no Solar System analogs. Advances in astronomical instrumentation and recent space missions have opened the sub-Earth frontier for exploration: the Kepler mission has discovered dozens of confirmed or candidate sub-Earths transiting their host stars. It can detect Mars-size planets around its smallest stellar targets, as well as exomoons of comparable size. Although the application of the Doppler method is currently limited by instrument stability, future spectrographs may detect equivalent planets orbiting close to nearby bright stars. Future space-based microlensing missions should be able to probe the sub-Earth population on much wider orbits. A census of sub-Earths will complete the reconnaissance of the exoplanet mass spectrum and test predictions of planet formation models, including whether low-mass M dwarf stars preferentially host the smallest planets. The properties of sub-Earths may reflect their low gravity, diverse origins, and environment, but they will be elusive: Observations of eclipsing systems by the James Webb Space Telescope may give us our first clues to the properties of these small worlds.

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The exoplanet microlensing survey by the proposed WFIRST Observatory

Cited by 8 publications

References 13 publications

Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification

Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification

GravityCam: Wide-field high-resolution high-cadence imaging surveys in the visible from the ground

Below One Earth: The Detection, Formation, and Properties of Subterrestrial Worlds

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