Biosignatures & Paleobiology

Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) III: Introducing the KEN

By Keith Cowing
Status Report
astro-ph.EP
November 25, 2024
Filed under , , , , , , , , , , ,
Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) III: Introducing the KEN
In the top panel, we present a representative spectrum from our work where molecular contributions are visible, with the y-axis representing the geometric albedo. In the bottom panel, we present the absorbance contributions of every molecule available in the KEN grids, as well as the Rayleigh scattering also included: H2O, O2, O3, CH4, CO, CO2, SO2, and N2O, with the y-axis representing absorption. The x-axes are both the full wavelength range of the KEN grids (0.2–2µm). Note that SO2 and N2O absorb at 0.2 µm very minimally, without features in other locations in this wavelength range. — astro-ph.EP

We deploy a newly-generated set of geometric albedo spectral grids to examine the detectability of methane (CH4) in the reflected-light spectrum of an Earth-like exoplanet at visible and near-infrared wavelengths with a future exoplanet imaging mission.

By quantifying the detectability as a function of signal-to-noise ratio (SNR) and molecular abundance, we can constrain the best methods of detection with the high-contrast space-based coronagraphy slated for the next generation telescopes such as the Habitable Worlds Observatory (HWO).

We used 25 bandpasses between 0.8 and 1.5 microns. The abundances range from a modern-Earth level to an Archean-Earth level, driven by abundances found in available literature. We constrain the optimal 20%, 30%, and 40% bandpasses based on the effective SNR of the data, and investigate the impact of spectral confusion between CH4 and H2O on the detectability of each one. We find that a modern-Earth level of CH4 is not detectable, while an Archean Earth level of CH4 would be detectable at all SNRs and bandpass widths.

Crucially, we find that CH4 detectability is inversely correlated with H2O abundance, with required SNR increasing as H2O abundance increases, while H2O detectability depends on CH4 abundance and selected observational wavelength, implying that science requirements for the characterization of Earth-like planet atmospheres in the VIS/NIR should consider the abundances of both species in tandem.

Natasha Latouf, Michael D. Himes, Avi M. Mandell, Michael Dane Moore, Vincent Kofman, Geronimo L. Villanueva, Chris Stark

Comments: 15 pages, 10 figures, accepted for publication in the Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2411.15089 [astro-ph.EP] (or arXiv:2411.15089v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2411.15089
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Submission history
From: Natasha Latouf
[v1] Fri, 22 Nov 2024 17:33:32 UTC (12,385 KB)
https://arxiv.org/abs/2411.15089

Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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