Large Interferometer For Exoplanets (LIFE): XIII. The Value of Combining Thermal Emission and Reflected Light for the Characterization of Earth Twins
Following the recommendations to NASA and ESA, the search for life on exoplanets will be a priority in the next decades. Two direct imaging space mission concepts are being developed: the Habitable Worlds Observatory (HWO) and the Large Interferometer for Exoplanets (LIFE).
HWO focuses on reflected light spectra in the ultraviolet/visible/near-infrared (UV/VIS/NIR), while LIFE captures the mid-infrared (MIR) emission of temperate exoplanets. We assess the potential of HWO and LIFE in characterizing a cloud-free Earth twin orbiting a Sun-like star at 10 pc, both separately and synergistically, aiming to quantify the increase in information from joint atmospheric retrievals on a habitable planet.
Retrieved pressure-temperature profiles for the second retrieval set (simplified noise): Left panel: pure HWO retrieval (magenta); Central panel: pure LIFE retrieval (blue); Right panel: HWO+LIFE retrieval (yellow). In all panels, the 2-σ and the 1-σ intervals are shown in increasingly darker hues, as well as the input profiles (black lines) for comparison. Inside each panel, the inset plot shows the 2D posterior space of the ground pressure and temperature. In all panels and the inset plots, the surface pressure and temperature point in the P−T space is shown as a red square marker. — astro-ph.EP
We perform Bayesian retrievals on simulated data from an HWO-like and a LIFE-like mission separately, then jointly, considering the baseline spectral resolutions currently assumed for these concepts and using two increasingly complex noise simulations. HWO would constrain H2O, O2, and O3, in the atmosphere, with ~ 100 K uncertainty on the temperature profile. LIFE would constrain CO2, H2O, O3 and provide constraints on the thermal atmospheric structure and surface temperature (~ 10 K uncertainty).
Both missions would provide an upper limit on CH4. Joint retrievals on HWO and LIFE data would accurately define the atmospheric thermal profile and planetary parameters, decisively constrain CO2, H2O, O2, and O3, and weakly constrain CO and CH4. The detection significance is greater or equal to single-instrument retrievals. Both missions provide specific information to characterize a terrestrial habitable exoplanet, but the scientific yield is maximized with synergistic UV/VIS/NIR+MIR observations.
Using HWO and LIFE together will provide stronger constraints on biosignatures and life indicators, potentially transforming the search for life in the universe.
Corner plot for the posterior distributions from the second set of retrievals (simplified noise). The black lines indicate the expected values for every parameter. The median and 1-σ uncertainties for relevant retrieved and derived parameters are shown in the table in the top right corner. The scenarios are color-coded according to Table 3. — astro-ph.EP
E. Alei, S. P. Quanz, B. S. Konrad, E. O. Garvin, V. Kofman, A. Mandell, D. Angerhausen, P. Mollière, M. R. Meyer, T. Robinson, S. Rugheimer, the LIFE Collaboration
Comments: 16 pages (main text, incl. 12 figures) + appendix; accepted for publication in A&A (current version: post 1st revision). Thirteenth paper of LIFE telescope series
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2406.13037 [astro-ph.EP] (or arXiv:2406.13037v1 [astro-ph.EP] for this version)
Submission history
From: Eleonora Alei
[v1] Tue, 18 Jun 2024 20:04:35 UTC (1,697 KB)
https://arxiv.org/abs/2406.13037
Astrobiology, Astrochemistry,
