arXiv subjects

Celeste Hagee

Publications and source records attributed to Celeste Hagee.

3 recordsLinked to original sources

arXiv2026

Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) IV: Analyzing CO2 Detections in the Near-IR to Determine the Long-Wavelength Cut-off for the Habitable Worlds Observatory Coronagraph

We present our analysis of how the detectability of carbon dioxide (CO2) on an Earth-like planet varies with respect to signal-to-noise ratio (SNR), wavelength, and molecular abundance. Using the Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) methodology, we can inform the optimal long-wavelength cut-off for the future Habitable Worlds Observatory (HWO) coronagraph. We test 25 evenly-spaced 20% bandpasses between 0.8-2.0μm, and simulate data spanning a range of SNRs and molecular abundance to analyze the relationship between wavelength and detectability for different planetary archetypes. We examine abundance levels from varying Earth epochs and a Venus-like archetype to investigate how detectability would change throughout the evolution of a rocky planet. Here, we present our results on the planetary conditions and technological requirements to strongly detect CO2. In addition, we analyze the degeneracy of CO2 with carbon monoxide (CO), methane (CH4), and water (H2O). We determine that any abundance of CO does not achieve strong detections and that CH4 and H2O play a pivotal role in the ability to detect CO2. We conclude that the optimal long-wavelength cut-off for the Habitable Worlds Observatory coronagraph should be 1.68μm.

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arXiv2025

Wavelength Requirements for Life Detection via Reflected Light Spectroscopy of Rocky Exoplanets

Searching for signs of life is a primary goal of the Habitable Worlds Observatory (HWO). However, merely detecting oxygen, methane, or other widely discussed biosignatures is insufficient evidence for a biosphere. In parallel with biosignature detection, exoplanet life detection additionally requires characterization of the broader physicochemical context to evaluate planetary habitability and the plausibility that life could produce a particular biosignature in a given environment. Life detection further requires that we can confidently rule out photochemical or geological phenomena that can mimic life. Evaluating false-positive scenarios may require different observatory specifications than biosignature detection surveys. Here, we explore the coronagraph requirements for assessing habitability and for excluding known false-positive (and false-negative) scenarios for oxygen and methane. We find that broad wavelength coverage ranging from the near ultraviolet (0.26 $\mu$m) and extending into the near infrared (1.7 $\mu$m) is necessary to contextualize these potential biosignatures with HWO. The short-wavelength cutoff is driven by the need to identify Proterozoic-like biospheres via O$_3$, whereas the long-wavelength cutoff is driven by the need to contextualize O$_2$ and CH$_4$ biosignatures via constraints on carbon-bearing atmospheric species. The ability to obtain spectra with signal-to-noise ratios of 20-40 across this 0.26-1.7 $\mu$m range (R=7 UV, R=140 VIS, and R=70 NIR) is also required. While not every Earth-analog biosignature and false positive can be unambiguously identified with these capabilities-and the plausibility and contextual clues of many biosignature false positives remain an area of active research-our minimal spectral recommendations would enable a broad search for Earth-like life assuming such observations are achievable for a meaningful number of HWO targets.

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arXiv2023

A Non-Detection of Iron in the First High-Resolution Emission Study of the Lava Planet 55 Cnc e

Close-in lava planets represent an extreme example of terrestrial worlds, but their high temperatures may allow us to probe a diversity of crustal compositions. The brightest and most well-studied of these objects is 55 Cancri e, a nearby super-Earth with a remarkably short 17-hour orbit. However, despite numerous studies, debate remains about the existence and composition of its atmosphere. We present upper limits on the atmospheric pressure of 55 Cnc e derived from high-resolution time-series spectra taken with Gemini-N/MAROON-X. Our results are consistent with current crustal evaporation models for this planet which predict a thin $\sim$ 100 mbar atmosphere. We conclude that, if a mineral atmosphere is present on 55 Cnc e, the atmospheric pressure is below 100 mbar.

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