Repeatability of Spitzer/Irac Exoplanetary Eclipses With Independent Component Analysis

Morello, Giuseppe; Waldmann, I. P.; Tinetti, Giovanna

doi:10.3847/0004-637x/820/2/86

Cited by 50 publications

(41 citation statements)

References 58 publications

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“…We take square arrays of pixels with the stellar centroid at their centers as fixed photometric apertures during each observation, following the same procedure as adopted by, e.g., Morello et al (2015Morello et al ( , 2016, and Ingalls et al (2016). The centroid position varies within the same pixel during each observation.…”

Section: Detrending Spitzer /Irac Datamentioning

confidence: 99%

A SEA BASS on the Exoplanet HD 209458b

Morello¹

2018

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We present here the first application of Stellar and Exoplanetary Atmospheres Bayesian Analysis Simultaneous Spectroscopy (SEA BASS) on real datasets. SEA BASS is a scheme that enables the simultaneous derivation of four-coefficient stellar limb-darkening profiles, transit depths, and orbital parameters from exoplanetary transits at multiple wavelengths. It relies on the wavelength-independence of the system geometry and on the reduced limb-darkening effect in the infrared. This approach has been introduced by Morello et al. (2017) (without the SEA BASS acronym), who discuss several tests on synthetic datasets. Here, we (1) improve on the original algorithm by using multiple Spitzer /InfraRed Array Camera passbands and a more effective set of geometric parameters, (2) demonstrate its ability with Hubble Space Telescope/Space Telescope Imaging Spectrograph datasets, by (3) measuring the HD209458 stellar limb-darkening profile over multiple passbands in the 290-570 nm range with sufficient precision to rule out some theoretical models that have been adopted previously in theliterature, and (4) simultaneously extracting the transmission spectrum of the exoplanet atmosphere. The higher photometric precision of the next-generation instruments, such as those onboard the James Webb Space Telescope, will enable modeling the star-planet systems with unprecedented detail, and increase the importance of SEA BASS for avoiding the potential biases introduced by inaccurate stellar limb-darkening models.

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Section: Detrending Spitzer /Irac Datamentioning

confidence: 99%

A SEA BASS on the Exoplanet HD 209458b

Morello¹

2018

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“…The original source signals are retrieved through a linear transformation that maximizes their Morello et al 2014Morello et al , 2015Morello et al , 2016Morello 2015) with excellent results. We refer the reader to those publications and the relevant cited literature for more technical details about ICA and the different implementations.…”

Section: Icamentioning

confidence: 99%

“…Following a standard ICA algorithm (e.g., Morello 2015; Morello et al 2016), we simultaneously fitted a transit model (with the same parameters as in Section 2.3) and a linear combination of the non-transit components to the relevant raw light curves. We computed the "stacked" and a "weighted" spectra, as described in Section 2.3.…”

Section: Fittingmentioning

confidence: 99%

“…Simply put, the ICA s term is the weighted sum of the errors attributed to the independent components extracted with ICA. We refer the reader to Morello et al (2015Morello et al ( , 2016 for additional details. The error bars for the weighted spectrum are calculated as the simple arithmetic means of the error bars derived from fitting the independent components to the single stripes.…”

Section: Final Error Barsmentioning

confidence: 99%

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Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3

Damiano

Morello

Tsiaras

et al. 2017

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We report here the analysis of the near-infrared transit spectrum of the hot Jupiter HAT-P-32b, which was recorded with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. HAT-P-32bis one of the most inflated exoplanets discovered, making it an excellent candidate for transit spectroscopic measurements. To obtain the transit spectrum, we have adopted different analysis methods, both parametric and non-parametric (Independent Component Analysis, ICA), and compared the results. The final spectra are all consistent within 0.5σ. The uncertainties obtained with ICA are larger than those obtained with the parametric method by a factor of ∼1.6-1.8. This difference is the tradeoff for higher objectivity due to the lack of any assumption about the instrument systematics compared to the parametric approach. The ICA error bars are therefore worst-case estimates. To interpret the spectrum of HAT-P-32b we used  -REx, our fully Bayesian spectral retrieval code. As for other hot Jupiters, the results are consistent with the presence of water vapor (log H O 3.45 2 1.65, clouds (top pressure between 5.16 and 1.73 bar). Spectroscopic data over a broader wavelength range are needed to de-correlate the mixing ratio of water vapor from clouds and identify other possible molecular species in the atmosphere of HAT-P-32b.

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“…In this paper we present an independent reanalysis of the three Spitzer /IRAC phase curves of WASP43 b using the wavelet pixel-Independent Component Analysis (ICA) pipeline (Morello et al 2016). We repeated the analysis by adopting different stellar limb-darkening models, which affect the retrieved transit parameters.…”

Section: Introductionmentioning

confidence: 99%

An Independent Analysis of the Spitzer/IRAC Phase Curves of WASP43 b

Morello

Danielski

Dickens

et al. 2019

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We present here a reanalysis of the Spitzer Space Telescope phase curves of the hot Jupiter WASP43 b, using the wavelet pixel-Independent Component Analysis, a blind signal-source separation method. The data analyzed were recorded with the InfraRed Array Camera and consisted of two visits at 3.6 µm, and one visit at 4.5 µm, each visit covering one transit and two eclipse events. To test the robustness of our technique we repeated the analysis on smaller portions of the phase curves, and by employing different instrument ramp models. Our reanalysis presents significant updates of the planetary parameters compared to those reported in the original phase curve study of WASP43 b. In particular, we found (1) higher nightside temperatures, (2) smaller hotspot offsets, (3) a greater consistency (∼1 σ) between the two 3.6 µm visits, and (4) a greater similarity with the predictions of the atmospheric circulation models. Our parameter results are consistent within 1 σ with those reported by a recent reanalysis of the same data sets. For each visit we studied the variation of the retrieved transit parameters as a function of various sets of stellar limb-darkening coefficients, finding significant degeneracy between the limb-darkening models and the analysis output. Furthermore, we performed the analysis of the single transit and eclipse events, and we examined the differences between these results with the ones obtained with the whole phase curve. Finally we provide a formula useful to optimize the trade-off between precision and duration of observations of transiting exoplanets.

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Repeatability of Spitzer/Irac Exoplanetary Eclipses With Independent Component Analysis

Cited by 50 publications

References 58 publications

A SEA BASS on the Exoplanet HD 209458b

A SEA BASS on the Exoplanet HD 209458b

Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3

An Independent Analysis of the Spitzer/IRAC Phase Curves of WASP43 b

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