Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE). II. Using Grid-based Nested Sampling in Coronagraphy Observation Simulations for O<sub>2</sub> and O<sub>3</sub>
Natasha Latouf, Avi M. Mandell, Gerónimo Villanueva, Michael D. Himes, Michael Dane Moore, Nicholas Susemiehl, Jaime Crouse, Shawn Domagal‐Goldman, Giada Arney, Vincent Kofman, Amber V. Young
Abstract
Abstract We present the results for the detectability of the O 2 and O 3 molecular species in the atmosphere of an Earth-like planet using reflected light at visible wavelengths. By quantifying the detectability as a function of the signal-to-noise ratio (S/N), we can constrain the best methods to detect these biosignatures with next-generation telescopes designed for high-contrast coronagraphy. Using 25 bandpasses between 0.515 and 1 μ m and a preconstructed grid of geometric albedo spectra, we examined the spectral sensitivity needed to detect these species for a range of molecular abundances. We first replicate a modern-Earth twin atmosphere to study the detectability of current O 2 and O 3 levels, and then expand to a wider range of literature-driven abundances for each molecule. We constrain the optimal 20%, 30%, and 40% bandpasses based on the effective S/N of the data, and define the requirements for the possibility of simultaneous molecular detection. We present our findings of O 2 and O 3 detectability as functions of the S/N, wavelength, and abundance, and discuss how to use these results for optimizing future instrument designs. We find that O 2 is detectable between 0.64 and 0.83 μ m with moderate-S/N data for abundances near that of modern Earth and greater, but undetectable for lower abundances consistent with a Proterozoic Earth. O 3 is detectable only at very high S/N data in the case of modern-Earth abundances; however, it is detectable at low-S/N data for higher O 3 abundances that can occur from efficient abiotic O 3 production mechanisms.