Characterizing Transiting Exoplanet Atmospheres With JWST

Greene, Thomas P.; Line, Michael R.; Montero, Cezar; Fortney, Jonathan J.; Lustig‐Yaeger, Jacob; Luther, Kyle

doi:10.3847/0004-637x/817/1/17

Cited by 497 publications

(574 citation statements)

References 98 publications

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“…Therefore we do not adopt these same noise floors and leave it up to the observer to input their own. In contrast to Greene et al (2016), noise floors are not added to σ prop,λ in quadrature. Instead, PandExo sets σ prop,λ (σ prop,λ < σ f,λ ) = σ f,λ .…”

Section: Pandexo: Simulating Jwst Observationsmentioning

confidence: 99%

“…The 1σ propagated error on the final spectrum, σ prop is: Greene et al (2016) argue that a systematic noise floor might inhibit JWST observations to get below 20 ppm, 30 ppm, and 50 ppm, for NIRISS SOSS, NIRCam grism, and MIRI LRS, respectively. This argument was based off of a comparison of the lowest noise achieved with an HST WFC3 G141 observations (Kreidberg et al 2014b) for the NIR instruments and the lowest noise achieved with a Spitzer Si:As observation (Knutson et al 2009) for MIRI.…”

Section: Pandexo: Simulating Jwst Observationsmentioning

confidence: 99%

“…Since then, many have sought to baseline the performance of JWST using independent sensitivity models (Kaltenegger & Traub 2009;Beichman et al 2014;Batalha et al 2015;Cowan et al 2015;Barstow et al 2015Barstow et al , 2016Greene et al 2016;Mordasini et al 2016;Mollière et al 2016,in press;Howe et al 2017;Batalha et al 2017). For example, Batalha et al (2015) reported that primary transit spectroscopy with NIRSpec of 1-10 M ⊕ , 400-1000 K planets orbiting M dwarfs would result in high SNR spectra if the planets were within ∼50 pc and if 25 transits were co-added.…”

Section: Introductionmentioning

confidence: 99%

“…Barstow et al (2015) explored these effects by including time varying astrophysical and instrumental systematics in their observational simulations. Greene et al (2016) used a retrieval algorithm with an independent noise simulator for NIRISS, NIRCam, and MIRI in order to determine what atmospheric properties could be retrieved from a hot Jupiter, warm Neptune, warm sub-Neptune and cool super-Earth. All of these were pivotal to our knowledge and understanding of the functionality of JWST observing modes and all of these relied on simulating noise sources.…”

Section: Introductionmentioning

confidence: 99%

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PandExo: A Community Tool for Transiting Exoplanet Science withJWST&HST

Batalha¹,

Mandell²,

Pontoppidan³

et al. 2017

PASP

323

250

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As we approach the James Webb Space Telescope (JWST) era, several studies have emerged that aim to: 1) characterize how the instruments will perform and 2) determine what atmospheric spectral features could theoretically be detected using transmission and emission spectroscopy. To some degree, all these studies have relied on modeling of JWST's theoretical instrument noise. With under two years left until launch, it is imperative that the exoplanet community begins to digest and integrate these studies into their observing plans, as well as think about how to leverage the Hubble Space Telescope (HST) to optimize JWST observations. In order to encourage this and to allow all members of the community access to JWST & HST noise simulations, we present here an open-source Python package and online interface for creating observation simulations of all observatory-supported timeseries spectroscopy modes. This noise simulator, called PandExo, relies on some aspects of Space Telescope Science Institute's Exposure Time Calculator, Pandeia. We describe PandExo and the formalism for computing noise sources for JWST. Then, we benchmark PandExo's performance against each instrument team's independently written noise simulator for JWST, and previous observations for HST. We find that PandExo is within 10% agreement for HST/WFC3 and for all JWST instruments.

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Section: Pandexo: Simulating Jwst Observationsmentioning

confidence: 99%

Section: Pandexo: Simulating Jwst Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

PandExo: A Community Tool for Transiting Exoplanet Science withJWST&HST

Batalha¹,

Mandell²,

Pontoppidan³

et al. 2017

PASP

323

250

View full text Add to dashboard Cite

show abstract

“…We use the CHIMERA transmission model (Line et al 2013a;Kreidberg et al 2014aKreidberg et al , 2015Swain et al 2014;Greene et al 2016;. For transit geometry, the code solves the radiative-transfer equation for parallel rays across the terminator of the planet (Brown 2001;Tinetti et al 2012).…”

Section: Linementioning

confidence: 99%

Community Targets of JWST’s Early Release Science Program: Evaluation of WASP-63b

Kilpatrick

Cubillos

Stevenson

et al. 2018

Self Cite

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We present observations of WASP-63b by the Hubble Space Telescope (HST) as part of "A Preparatory Program to Identify the Single Best Transiting Exoplanet for James Webb Space Telescope (JWST) Early Release Science (ERS)." WASP-63b is one of the community targets under consideration for the JWST ERS program. We present a spectrum derived from a single observation by HST Wide Field Camera3 in the near-infrared. We engaged groups across the transiting exoplanet community to participate in the analysis of the data and present results from each. Extraction of the transmission spectrum by several independent analyses find an H 2 O absorption feature with varying degrees of significance ranging from 1σ to 3σ. The feature, in all cases, is muted in comparison to a clear atmosphere at solar composition. The reasons for the muting of this feature are ambiguous due to a degeneracy between clouds and composition. The data does not yield robust detections of any molecular species other than H 2 O. The group was motivated to perform an additional set of retrieval exercises to investigate an apparent bump in the spectrum at ∼1.55 μm. We explore possible disequilibrium chemistry and find this feature is consistent with super-solar HCN abundance but it is questionable if the required mixing ratio of HCN is chemically and physically plausible. The ultimate goal of this study is to vet WASP-63b as a potential community target to best demonstrate the capabilities and systematics of JWST instruments for transiting exoplanet science. In the case of WASP-63b, the presence of a detectable water feature indicates that WASP-63b remains a plausible target for JWST observations.

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Illusion and reality in the atmospheres of exoplanets

2017

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The atmospheres of exoplanets reveal all their properties beyond mass, radius, and orbit. Based on bulk densities, we know that exoplanets larger than 1.5 Earth radii must have gaseous envelopes and, hence, atmospheres. We discuss contemporary techniques for characterization of exoplanetary atmospheres. The measurements are difficult, because—even in current favorable cases—the signals can be as small as 0.001% of the host star's flux. Consequently, some early results have been illusory and not confirmed by subsequent investigations. Prominent illusions to date include polarized scattered light, temperature inversions, and the existence of carbon planets. The field moves from the first tentative and often incorrect conclusions, converging to the reality of exoplanetary atmospheres. That reality is revealed using transits for close‐in exoplanets and direct imaging for young or massive exoplanets in distant orbits. Several atomic and molecular constituents have now been robustly detected in exoplanets as small as Neptune. In our current observations, the effects of clouds and haze appear ubiquitous. Topics at the current frontier include the measurement of heavy element abundances in giant planets, detection of carbon‐based molecules, measurement of atmospheric temperature profiles, definition of heat circulation efficiencies for tidally locked planets, and the push to detect and characterize the atmospheres of super‐Earths. Future observatories for this quest include the James Webb Space Telescope and the new generation of extremely large telescopes on the ground. On a more distant horizon, NASA's study concepts for the Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/Infrared Surveyor (LUVOIR) missions could extend the study of exoplanetary atmospheres to true twins of Earth.

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Characterizing Transiting Exoplanet Atmospheres With JWST

Cited by 497 publications

References 98 publications

PandExo: A Community Tool for Transiting Exoplanet Science withJWST&HST

PandExo: A Community Tool for Transiting Exoplanet Science withJWST&HST

Community Targets of JWST’s Early Release Science Program: Evaluation of WASP-63b

Illusion and reality in the atmospheres of exoplanets

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