Exoplanets & Exomoons

Large Interferometer For Exoplanets (LIFE): XI. Phase-space Synthesis Decomposition For Planet Detection And Characterization

By Keith Cowing
Status Report
August 3, 2023
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Large Interferometer For Exoplanets (LIFE): XI. Phase-space Synthesis Decomposition For Planet Detection And Characterization
Image and spectrum reconstruction under photon-noise limited condition. (a) Reconstructed two-dimensional image. The white arrows denote positions of planet P1, planet P2, planet P3, respectively. The integration time was set to 55 h. The unit of the color bar is the number of photoelectrons. Reconstructed spectra of three planets (b) P1, (c) P2, and (d) P3 for an integration time of 75 days. The grey line and grey vertical bar of each panel show the input model and the standard deviation of each data point derived through 100 numerical simulations, respectively — astro-ph.IM

A mid-infrared nulling-space interferometer is a promising way to characterize thermal light from habitable planet candidates around Sun-like stars.

However, one of the main challenges for achieving this ambitious goal is a high-precision stability of the optical path difference (OPD) and amplitude over a few days for planet detection and up to a few weeks for in-depth characterization.

Here we propose a new method called phase-space synthesis decomposition (PSSD) to shorten the stability requirement to minutes, significantly relaxing the technological challenges of the mission. Focusing on what exactly modulates the planet signal in the presence of the stellar leak and systematic error, PSSD prioritizes the modulation of the signals along the wavelength domain rather than baseline rotation.

Modulation along the wavelength domain allows us to extract source positions in parallel to the baseline vector for each exposure. The sum of the one-dimensional data converts into two-dimensional information. Based on the reconstructed image, we construct a continuous equation and extract the spectra through the singular value decomposition (SVD) while efficiently separating them from a long-term systematic stellar leak.

We performed numerical simulations to investigate the feasibility of PSSD for the LIFE mission concept. We confirm that multiple terrestrial planets in the habitable zone around a Sun-like star at 10 pc can be detected and characterized despite high levels and long durations of systematic noise.

We also find that PSSD is more robust against a sparse sampling of the array rotation compared to purely rotation-based signal extraction. Using PSSD as signal extraction method significantly relaxes the technical requirements on signal stability and further increases the feasibility of the LIFE mission.

Taro Matsuo, Felix Dannert, Romain Laugier, Sascha P. Quanz, Andjelka B. Kovacevic, LIFE collaboration

Comments: Accepted for publication by A&A – 14 pages main text including 10 Figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2308.01478 [astro-ph.IM] (or arXiv:2308.01478v1 [astro-ph.IM] for this version)
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Submission history
From: Taro Matsuo
[v1] Thu, 3 Aug 2023 00:07:59 UTC (1,335 KB)

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) 🖖🏻