Detection of Carbon Monoxide in the Atmosphere of WASP-39b Applying Standard Cross-Correlation Techniques to JWST NIRSpec G395H Data

TL;DR

This paper confirms the detection of carbon monoxide in the atmosphere of exoplanet WASP-39b using JWST NIRSpec G395H data and cross-correlation techniques, demonstrating the method's effectiveness in analyzing medium-resolution spectra.

Contribution

The study applies standard cross-correlation techniques to high-resolution JWST data to confirm CO detection and identify isotopologues in an exoplanet atmosphere, advancing atmospheric characterization methods.

Findings

CO detected with 6.6 sigma significance using ${ m ^{12}C^{16}O}$ lines

Significance increases to 7.5 sigma when including isotopologues, especially ${ m ^{13}C^{16}O}$

Highlights the effectiveness of cross-correlation in analyzing medium-resolution spectra for atmospheric composition

Abstract

Carbon monoxide was recently reported in the atmosphere of the hot Jupiter WASP-39b using the NIRSpec PRISM transit observation of this planet, collected as part of the JWST Transiting Exoplanet Community Early Release Science (JTEC ERS) Program. This detection, however, could not be confidently confirmed in the initial analysis of the higher resolution observations with NIRSpec G395H disperser. Here we confirm the detection of CO in the atmosphere of WASP-39b using the NIRSpec G395H data and cross-correlation techniques. We do this by searching for the CO signal in the unbinned transmission spectrum of the planet between 4.6 and 5.0 $\mu$m, where the contribution of CO is expected to be higher than that of other anticipated molecules in the planet's atmosphere. Our search results in a detection of CO with a cross-correlation function (CCF) significance of $6.6 \sigma$ when using a template with only ${\rm ^{12}C^{16}O}$ lines. The CCF significance of the CO signal increases to $7.5 \sigma$ when including in the template lines from additional CO isotopologues, with the largest contribution being from ${\rm ^{13}C^{16}O}$. Our results highlight how cross-correlation techniques can be a powerful tool for unveiling the chemical composition of exoplanetary atmospheres from medium-resolution transmission spectra, including the detection of isotopologues.