A Simple Depth-of-Search Metric for Exoplanet Imaging Surveys

Garrett, Daniel; Savransky, Dmitry; Macintosh, Bruce

doi:10.3847/1538-3881/aa78f6

Cited by 29 publications

(7 citation statements)

References 41 publications

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“…1. Depth-of-search grid: Given a particular system, we obtain its imageable region by computing the depth-ofsearch grids as defined by Garrett et al (2017). For given values of a and R, the corresponding bin represents the conditional probability of detecting a hypothetically existing planet (i.e., completeness Brown (2005)) according to the considered instrument's design and capabilities.…”

Section: Single-planet Systems Prioritizationmentioning

confidence: 99%

“…where r has been replaced by a, since the depth-of-search grids are defined assuming that e " 0 (Garrett et al, 2017). Since the width of the imageable region increases with R, the maximum semi-major axis a max is consequently given by the upper bounding solution of the equation F pa | R max q " 0, where again R max is the largest planetary radius considered.…”

Section: Single-planet Systems Prioritizationmentioning

confidence: 99%

“…In particular, regarding the construction of an optimized target list, it is essential to previously identify which systems are more likely to host an imageable planet. Garrett et al (2017) addressed this problem by defining the depth-of-search grids in the (a, R) space, where the value of each bin represented the probability of detecting a planet with semi-major axis a and radius R. The resultant imageable region was obtained according only to the instrument's performance and capabilities, allowing for the estimation of the expected number of detected planets (i.e., total completeness) by convolution with the desired grid of occurrence rates.…”

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confidence: 99%

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Analytic Stability Maps of Unknown Exoplanet Companions for Imaging Prioritization

Gascón

Savransky

Sureda

2020

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Identifying which systems are more likely to host an imageable planet can play an important role in the construction of an optimized target list for future direct imaging missions, such as the planned technology demonstration for the Wide Field Infrared Survey Telescope (WFIRST). For single-planet systems, the presence of an already detected exoplanet can severely restrict the target's stable region and should therefore be considered when searching for unknown companions. To do so, we first analyze the performance and robustness of several two-planet stability criteria by comparing them with long-term numerical simulations. We then derive the necessary formulation for the computation of (a, R) analytic stability maps, which can be used in conjunction with depthof-search grids in order to define the stable-imageable region of a system. The dynamically stable completeness (i.e., the expected number of imageable and stable planets) can then be calculated via convolution with the selected occurrence grid, obtaining a metric that can be directly compared for imaging prioritization. Applying this procedure to all the currently known single-planet systems within a distance of 50 pc, we construct a ranked target list based on the WFIRST CGI's predicted performance and SAG13 occurrence rates.

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Section: Single-planet Systems Prioritizationmentioning

confidence: 99%

Section: Single-planet Systems Prioritizationmentioning

confidence: 99%

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confidence: 99%

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Analytic Stability Maps of Unknown Exoplanet Companions for Imaging Prioritization

Gascón

Savransky

Sureda

2020

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“…3,4,7 When completeness is evaluated for each star in a full target list, summed, and scaled by the expected number of planets from that population per star (η), we arrive at the expected number of planets to be detected from that population by that mission. 8 While this technique can be used to quickly evaluate a mission's performance, it abrogates temporal constraints and uncertainties, such as target visibility, variable overhead times, changing local zodiacal light intensity, and unscheduled characterizations of newly detected planets. Solely using completeness to evaluate a mission can therefore only provide an upper bound for expected performance.…”

Section: Introductionmentioning

confidence: 99%

Optimal scheduling of exoplanet direct imaging single-visit observations of a blind search survey

Keithly

Savransky

Garrett

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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We present an algorithm, effective over a broad range of planet populations and instruments, for optimizing integration times of an exoplanet direct imaging observation schedule, to maximize the number of unique exoplanet detections under realistic mission constraints. Our planning process uses "completeness" as a reward metric and the nonlinear combination of optimal integration time per target and constant overhead time per target as a cost metric constrained by a total mission time. We validate our planned target list and integration times for a specific telescope by running a Monte Carlo of full mission simulations using EXOSIMS, a code base for simulating telescope survey missions. These simulations encapsulate dynamic details such as time-varying local zodiacal light for each star, planet keep-out regions, exoplanet positions, and strict enforcement of observatory use over time. We test our methods on the Wide-Field Infrared Survey Telescope (WFIRST) coronagraphic instrument (CGI). We find that planet, Sun, and solar panel keep-out regions limit some target per-annum visibility to <28% and that the mean local zodiacal light flux for optimally scheduled observations is 22.79 mag arcsec −2. Both these values are more pessimistic than previous approximations and impact the simulated mission yield. We find that the WFIRST CGI detects 5.48 AE 0.17 and 16.26 AE 0.51 exoplanets, on average, when observing two different planet populations based on Kepler Q1-Q6 data and the full Kepler data release, respectively. Optimizing our planned observations using completeness derived from the more pessimistic planet population (in terms of overall planet occurrence rates) results in a more robust yield than optimization based on the more optimistic planet population. We also find optimization based on the more pessimistic population results in more small planet detections than optimization with the more optimistic population. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Given an mission lifetime and a survey strategy (which include a fraction of the time for follow up observations), the former can be quantified using the methods described in the literature. 6,43,44 Note that the latter is somewhat more qualitative since it depends on how much of the followup/characterization time is dedicated to a given system. Because detection will be carried out in the Optical channel, nearby stars will be observed using the APLC since these sources will not suffer from the relatively large IW A DH and benefit from the robustness to stellar angular size.…”

Section: Impact On Performancementioning

confidence: 99%

The LUVOIR architecture ``A'' coronagraph instrument

Pueyo

Zimmerman

Bolcar

et al. 2017

UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VIII

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In preparation for the Astro 2020 Decadal Survey NASA has commissioned the study four flagship missions spanning to a wide range of observable wavelengths: the Origins Space Telescope (OST, formerly the Far-Infrared Surveyor), Lynx (formerly the X-ray Surveyor), the Large UV/Optical/Infrared Surveyor (LUVOIR) and the Habitable Exoplanet Imager (HabEx). One of the key scientific objectives of the latter two is the detection and characterization of the earth-like planets around nearby stars using the direct imaging technique (along with a broad range of investigations regarding the architecture of and atmospheric composition exoplanetary systems using this technique). As a consequence dedicated exoplanet instruments are being studied for these mission concepts. This paper discusses the design of the coronagraph instrument for the architecture "A" (15 meters aperture) of LUVOIR. The material presented in this paper is aimed at providing an overview of the LUVOIR coronagraph instrument. It is the result of four months of discussions with various community stakeholders (scientists and technologists) regarding the instrument's basic parameters followed by meticulous design work by the the GSFC Instrument Design Laboratory team. In the first section we review the main science drivers, presents the overall parameters of the instrument (general architecture and backend instrument) and delve into the details of the currently envisioned coronagraph masks along with a description of the wavefront control architecture. Throughout the manuscript we describe the trades we made during the design process. Because the vocation of this study is to provide a baseline design for the most ambitious earth-like finding instrument that could be possibly launched into the 2030's, we have designed an complex system privileged that meets the ambitious science goals out team was chartered by the LUVOIR STDT exoplanet Working Group. However in an effort to minimize technological risk we tried to maximize the number of technologies that will be matured by the WFIRST coronagraph instruments.

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A Simple Depth-of-Search Metric for Exoplanet Imaging Surveys

Cited by 29 publications

References 41 publications

Analytic Stability Maps of Unknown Exoplanet Companions for Imaging Prioritization

Analytic Stability Maps of Unknown Exoplanet Companions for Imaging Prioritization

Optimal scheduling of exoplanet direct imaging single-visit observations of a blind search survey

The LUVOIR architecture ``A'' coronagraph instrument

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