Large Interferometer For Exoplanets (LIFE): XII. The Detectability of Capstone Biosignatures in the Mid-Infrared — Sniffing Exoplanetary Laughing Gas and Methylated Halogens
This study aims to identify exemplary science cases for observing N2O, CH3Cl, and CH3Br in exoplanet atmospheres at abundances consistent with biogenic production using a space-based mid-infrared nulling interferometric observatory, such as the LIFE (Large Interferometer For Exoplanets) mission concept.
Distance distribution of HZ planet populations around M and FGK-type stars detectable with LIFE in the current baseline setup (see Table 1). Left: Detection yield predictions for planets around M-type stars with an underlying AFGKM exoplanet population following occurrence rate estimates from NASA’s ExoPaG SAG13 (Kopparapu et al. 2018) and Dressing & Charbonneau (2015). Right: Detection yield predictions around FGK-type stars with an underlying FGK exoplanet population based on occurence rates from Bryson et al. (2021). We differentiate between three HZ definitions: optimistic (opt) HZ, conservative (con) HZ and exo-Earth candidates (EECs). The bars show the predicted median planet yields and 1-σ uncertainties derived from the Monte Carlo simulations. — astro-ph.EP
This study aims to identify exemplary science cases for observing N2O, CH3Cl, and CH3Br in exoplanet atmospheres at abundances consistent with biogenic production using a space-based mid-infrared nulling interferometric observatory, such as the LIFE (Large Interferometer For Exoplanets) mission concept.
We use a set of scenarios derived from chemical kinetics models that simulate the atmospheric response of varied levels of biogenic production of N2O, CH3Cl and CH3Br in O2-rich terrestrial planet atmospheres to produce forward models for our LIFEsim observation simulator software. In addition we demonstrate the connection to retrievals for selected cases.
We use the results to derive observation times needed for the detection of these scenarios and apply them to define science requirements for the mission. Our analysis shows that in order to detect relevant abundances with a mission like LIFE in it’s current baseline setup, we require:
(i) only a few days of observation time for certain very near-by “Golden Target” scenarios, which also motivate future studies of “spectral-temporal” observations
(ii) ∼10 days in certain standard scenarios such as temperate, terrestrial planets around M star hosts at 5 pc,
(iii) ∼50 – 100 days in the most challenging but still feasible cases, such as an Earth twin at 5pc. A few cases for very low fluxes around specific host stars are not detectable.
In summary, abundances of these capstone biosignatures are detectable at plausible biological production fluxes for most cases examined and for a significant number of potential targets.
Detectability of various fluxes of N2O in the emission spectrum of an Earth-like planet around a (from top left to bottom right:) Sun-like, K6V, Proxima Centauri type and Trappist-like star at 5pc, after 50 days of observation with LIFE.Top: planet flux for atmospheres with and without N2O . The grey area represents the 1-σ sensitivity; the dark grey error bars show an individual simulated observation. Bottom: Statistical significance of the detected differences between an atmospheric models with and without N2O. For the Sun-like case the main contribution to the detectability is in the 16-18 µm band. For the later type star cases the differences especially in the 8-9 µm (see also discussion in Section 4.1. — astro-ph.EP
Daniel Angerhausen, Daria Pidhorodetska, Michaela Leung, Janina Hansen, Eleonora Alei, Felix Dannert, Jens Kammerer, Sascha P. Quanz, Edward W. Schwieterman
Comments: Accepted to be published in AJ. 42 pages, 23 figures, 14 tables. Accepted for publication
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2401.08492 [astro-ph.EP] (or arXiv:2401.08492v1 [astro-ph.EP] for this version) https://doi.org/10.48550/arXiv.2401.08492
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From: Daniel Angerhausen
[v1] Tue, 16 Jan 2024 16:50:31 UTC (7,346 KB)
https://arxiv.org/abs/2401.08492
Astrobiology,
