Exoplanets detection limits using spectral cross-correlation with spectro-imaging. An analytical model applied to the case of ELT-HARMONI

The combination of high-contrast imaging and medium to high spectral resolution spectroscopy offers new possibilities for the detection and characterization of exoplanets. The molecular mapping technique uses the difference between the planetary and stellar spectra. While traditional post-processing techniques are quickly limited by speckle noise at short angular separation, it efficiently suppresses speckles. Its performance depends on multiple parameters such as the star magnitude, the adaptive optics residual halo, the companion spectrum, the telluric absorption, as well as the telescope and instrument properties. Exploring this parameter space through end-to-end simulations to predict potential science cases and to optimize future instrument designs is very time-consuming, making it difficult to draw conclusions. We propose to define an efficient methodology for such an analysis. Explicit expressions of the estimates of signal and noise are derived, and they are validated through comparisons with end-to-end simulations. They provide an understanding of the instrumental dependencies, and help to discuss optimal instrumental choices with regard to the targets of interest. They are applied in the case of ELT/HARMONI, as a tool to predict the contrast performance in various observational cases. We confirm the potential of molecular mapping for high-contrast detections, especially for cool planets at short separations. We provide guidelines based on quantified estimates for design trade-offs of future instruments. We discuss the planet detection performances of HARMONI observing modes. While they nicely cover the appropriate requirements for high detection capability of warm exoplanets, a transmission extended down to J band would be beneficial. A contrast of a few 1E-7 at 50mas should be within reach on bright targets in photon noise regime with molecular mapping.Comment: 19 page

Integrated photonic-based coronagraphic systems for future space telescopes

The detection and characterization of Earth-like exoplanets around Sun-like stars is a primary science motivation for the Habitable Worlds Observatory. However, the current best technology is not yet advanced enough to reach the 10^-10 contrasts at close angular separations and at the same time remain insensitive to low-order aberrations, as would be required to achieve high-contrast imaging of exo-Earths. Photonic technologies could fill this gap, potentially doubling exo-Earth yield. We review current work on photonic coronagraphs and investigate the potential of hybridized designs which combine both classical coronagraph designs and photonic technologies into a single optical system. We present two possible systems. First, a hybrid solution which splits the field of view spatially such that the photonics handle light within the inner working angle and a conventional coronagraph that suppresses starlight outside it. Second, a hybrid solution where the conventional coronagraph and photonics operate in series, complementing each other and thereby loosening requirements on each subsystem. As photonic technologies continue to advance, a hybrid or fully photonic coronagraph holds great potential for future exoplanet imaging from space.Comment: Conference Proceedings of SPIE: Techniques and Instrumentation for Detection of Exoplanets XI, vol. 12680 (2023

Visible extreme adaptive optics on extremely large telescopes: Towards detecting oxygen in Proxima Centauri b and analogs

Looking to the future of exo-Earth imaging from the ground, core technology developments are required in visible extreme adaptive optics (ExAO) to enable the observation of atmospheric features such as oxygen on rocky planets in visible light. UNDERGROUND (Ultra-fast AO techNology Determination for Exoplanet imageRs from the GROUND), a collaboration built in Feb. 2023 at the Optimal Exoplanet Imagers Lorentz Workshop, aims to (1) motivate oxygen detection in Proxima Centauri b and analogs as an informative science case for high-contrast imaging and direct spectroscopy, (2) overview the state of the field with respect to visible exoplanet imagers, and (3) set the instrumental requirements to achieve this goal and identify what key technologies require further development.Comment: SPIE Proceeding: 2023 / 12680-6

Détection et caractérisation des atmosphères exoplanétaires par couplage de l'imagerie directe et de la spectroscopie à moyenne ou haute résolution spectrale

Medium or high spectral resolution is highly significant for characterizing the composition of planetary atmospheres, and is essential for the search for bio-signatures. Coupling techniques between spectroscopy and direct imaging instruments are emerging to meet these needs. These new instruments may also prove useful in facilitating detection and overcoming the current limitations of high-contrast imaging. A new dedicated detection technique was developed in 2017 known as molecular mapping.It is within this research framework that my thesis took place. Initially, I estimated the detection levels of the high-contrast arm on the future ELT/HARMONI instrument. These estimates led to the development of a general analytical method for predicting the detection levels of instruments combining high-contrast and high spectral resolution. I implemented a python code, FastCurves, enabling this method to be applied subsequently to other instruments, such as ERIS/SPIFFIER and SPHERE+/MedRES. This study demonstrated the benefits of equipping SPHERE with a medium spectral resolution field spectrograph. In the case of ERIS/SPIFFIER, I showed that the instrument's calibrations and data reduction performance were not yet sufficiently advanced to enable the effective detection of short-separation planets. Nevertheless, the data taken during the instrument's verification program enabled me to redetect a recently discovered planet, 2M0437 b. This detection also allows me to discuss the efficiency and dependencies of this new detection method. These latter limitations led me to discuss other detection methods that also make use of the spectral diversity of the data.Secondly, I present my work on the development at IPAG of a spectrometer optimized for characterizing exoplanets at high spectral resolution (R=80000). I worked on the development of alignment and calibration procedures to validate the spectrometer's operation. I then developed a signal extraction routine to extract the high-resolution spectrum of observed objects. The instrument was validated in real-life conditions by coupling it to the Hale telescope on Mount Palomar in March 2022. Since then, the VIPA spectrometer has entered a new phase of improvement in preparation for more ambitious future sky missions in 2024.La moyenne ou haute résolution spectrale a un intérêt scientifique fort pour caractériser la composition des atmosphères planétaires et s'avère nécessaire à la recherche de bio-signatures. Des techniques de couplage entre la spectroscopie et les instruments d'imagerie directe émergent pour répondre à ces besoins. Ces nouveaux instruments peuvent également s'avérer utiles pour faciliter les détections et dépasser les limites actuelles de l'imagerie haut-contraste. Une nouvelle technique de détection et de caractérisation dédiée a été élaborée en 2017 sous le nom de molecular mapping.C'est dans ce cadre de recherche que s'est déroulée ma thèse. Dans un premier temps, j'ai estimé les niveaux de détection du bras haut-contraste sur le futur instrument ELT/HARMONI. Ces estimations ont abouti au développement d'une méthode analytique générale pour prédire les niveaux de détection d'instruments mêlant haut-contraste et haute résolution spectrale. J'ai mis en place un code python, FastCurves, permettant d'appliquer cette méthode par la suite à d'autres instruments, comme notamment pour ERIS/SPIFFIER et SPHERE+/MedRES. Cette étude a permis de montrer l'intérêt d'équiper SPHERE d'un spectrographe de champ à moyenne résolution spectrale. Dans le cas d'ERIS/SPIFFIER, j'ai montré que les calibrations et les performances de réduction de données de l'instrument n'étaient pas encore assez perfectionnées pour permettre de détecter efficacement des planètes à courte séparation. Les données prises lors du programme de vérification de l'instrument m'ont tout de même permis de redétecter une planète, 2M0437 b, récemment découverte. Cette détection permet également de discuter de l'efficacité et des dépendances de cette nouvelle méthode de détection. Ces dernières limitations m'ont amené à discuter d'autres méthodes de détection utilisant également la diversité spectrale des données.Dans un second temps, je présente mes travaux sur le développement à l'IPAG d'un spectromètre optimisé pour la caractérisation d'exoplanètes à haute résolution spectrale (R=80000). J'ai travaillé sur la mise au point de procédures d'alignement et de calibration pour valider le fonctionnement du spectromètre. J'ai ensuite développé une routine d'extraction du signal pour extraire le spectre à haute résolution des objets observés. L'instrument a été validé en conditions réelles en le couplant au télescope de Hale du Mont Palomar en mars 2022. Depuis, le spectromètre VIPA entre dans une nouvelle phase d'amélioration pour la préparation de futures missions sur ciel plus ambitieuses à l'horizon 2024

Détection et caractérisation des atmosphères exoplanétaires par couplage de l'imagerie directe et de la spectroscopie à moyenne ou haute résolution spectrale

Medium or high spectral resolution is highly significant for characterizing the composition of planetary atmospheres, and is essential for the search for bio-signatures. Coupling techniques between spectroscopy and direct imaging instruments are emerging to meet these needs. These new instruments may also prove useful in facilitating detection and overcoming the current limitations of high-contrast imaging. A new dedicated detection technique was developed in 2017 known as molecular mapping.It is within this research framework that my thesis took place. Initially, I estimated the detection levels of the high-contrast arm on the future ELT/HARMONI instrument. These estimates led to the development of a general analytical method for predicting the detection levels of instruments combining high-contrast and high spectral resolution. I implemented a python code, FastCurves, enabling this method to be applied subsequently to other instruments, such as ERIS/SPIFFIER and SPHERE+/MedRES. This study demonstrated the benefits of equipping SPHERE with a medium spectral resolution field spectrograph. In the case of ERIS/SPIFFIER, I showed that the instrument's calibrations and data reduction performance were not yet sufficiently advanced to enable the effective detection of short-separation planets. Nevertheless, the data taken during the instrument's verification program enabled me to redetect a recently discovered planet, 2M0437 b. This detection also allows me to discuss the efficiency and dependencies of this new detection method. These latter limitations led me to discuss other detection methods that also make use of the spectral diversity of the data.Secondly, I present my work on the development at IPAG of a spectrometer optimized for characterizing exoplanets at high spectral resolution (R=80000). I worked on the development of alignment and calibration procedures to validate the spectrometer's operation. I then developed a signal extraction routine to extract the high-resolution spectrum of observed objects. The instrument was validated in real-life conditions by coupling it to the Hale telescope on Mount Palomar in March 2022. Since then, the VIPA spectrometer has entered a new phase of improvement in preparation for more ambitious future sky missions in 2024.La moyenne ou haute résolution spectrale a un intérêt scientifique fort pour caractériser la composition des atmosphères planétaires et s'avère nécessaire à la recherche de bio-signatures. Des techniques de couplage entre la spectroscopie et les instruments d'imagerie directe émergent pour répondre à ces besoins. Ces nouveaux instruments peuvent également s'avérer utiles pour faciliter les détections et dépasser les limites actuelles de l'imagerie haut-contraste. Une nouvelle technique de détection et de caractérisation dédiée a été élaborée en 2017 sous le nom de molecular mapping.C'est dans ce cadre de recherche que s'est déroulée ma thèse. Dans un premier temps, j'ai estimé les niveaux de détection du bras haut-contraste sur le futur instrument ELT/HARMONI. Ces estimations ont abouti au développement d'une méthode analytique générale pour prédire les niveaux de détection d'instruments mêlant haut-contraste et haute résolution spectrale. J'ai mis en place un code python, FastCurves, permettant d'appliquer cette méthode par la suite à d'autres instruments, comme notamment pour ERIS/SPIFFIER et SPHERE+/MedRES. Cette étude a permis de montrer l'intérêt d'équiper SPHERE d'un spectrographe de champ à moyenne résolution spectrale. Dans le cas d'ERIS/SPIFFIER, j'ai montré que les calibrations et les performances de réduction de données de l'instrument n'étaient pas encore assez perfectionnées pour permettre de détecter efficacement des planètes à courte séparation. Les données prises lors du programme de vérification de l'instrument m'ont tout de même permis de redétecter une planète, 2M0437 b, récemment découverte. Cette détection permet également de discuter de l'efficacité et des dépendances de cette nouvelle méthode de détection. Ces dernières limitations m'ont amené à discuter d'autres méthodes de détection utilisant également la diversité spectrale des données.Dans un second temps, je présente mes travaux sur le développement à l'IPAG d'un spectromètre optimisé pour la caractérisation d'exoplanètes à haute résolution spectrale (R=80000). J'ai travaillé sur la mise au point de procédures d'alignement et de calibration pour valider le fonctionnement du spectromètre. J'ai ensuite développé une routine d'extraction du signal pour extraire le spectre à haute résolution des objets observés. L'instrument a été validé en conditions réelles en le couplant au télescope de Hale du Mont Palomar en mars 2022. Depuis, le spectromètre VIPA entre dans une nouvelle phase d'amélioration pour la préparation de futures missions sur ciel plus ambitieuses à l'horizon 2024

HARMONI at ELT: system analysis and performance estimation of the high-contrast module

International audienc

High-resolution spectroscopy of diffraction-limited sources: laboratory tests of an innovative near-IR demonstrator

Current high-resolution spectrometers have been designed for seeing-limited sources. Designing a spectrometer for diffraction-limited sources makes it possible to significantly improves its compacity and cost, but it also opens up new concepts, including better efficiency, and adaptability to various spectral domains, and up to very high resolution (several 10⁵). A novel, near-IR, R~80000 spectrometer has been developed at IPAG to characterize two sources at once in the H or K bands. Its design is based on a virtually imaged phased array instead of an échelle grating, which allows the spectrometer to fit inside a 0.2 m³ cryostat, and results in a gain in throughput with respect to usual échelle spectrographs. One specific science case that can benefit from this new type of design is the characterization of exoplanets' atmosphere. This paper presents the results of its test in the laboratory, as well as the preparation for an on-sky demonstration tentatively scheduled for summer 2020

Chasing rainbows and ocean glints: Inner working angle constraints for the Habitable Worlds Observatory

NASA is engaged in planning for a Habitable Worlds Observatory (HabWorlds ), a coronagraphic space mission to detect rocky planets in habitable zones and establish their habitability. Surface liquid water is central to the definition of planetary habitability. Photometric and polarimetric phase curves of starlight reflected by an exoplanet can reveal ocean glint, rainbows, and other phenomena caused by scattering by clouds or atmospheric gas. Direct imaging missions are optimized for planets near quadrature, but HabWorlds ’ coronagraph may obscure the phase angles where such optical features are strongest. The range of accessible phase angles for a given exoplanet will depend on the planet’s orbital inclination and/or the coronagraph’s inner working angle (IWA). We use a recently created catalog relevant to HabWorlds of 164 stars to estimate the number of exo-Earths that could be searched for ocean glint, rainbows, and polarization effects due to Rayleigh scattering. We find that the polarimetric Rayleigh scattering peak is accessible in most of the exo-Earth planetary systems. The rainbow due to water clouds at phase angles of ∼20° − 60° would be accessible with HabWorlds  for a planet with an Earth equivalent instellation in ∼46 systems, while the ocean glint signature at phase angles of ∼130° − 170° would be accessible in ∼16 systems, assuming an IWA = 62 mas (3λ/D). Improving the IWA = 41 mas (2λ/D) increases accessibility to rainbows and glints by factors of approximately 2 and 3, respectively. By observing these scattering features, HabWorlds could detect a surface ocean and water cycle, key indicators of habitability.ISSN:0035-8711ISSN:1365-296

Visible extreme adaptive optics on extremely large telescopes: towards detecting oxygen in Proxima Centauri b and analogs

International audienceLooking to the future of exo-Earth imaging from the ground, core technology developments are required in visible Extreme Adaptive Optics (ExAO) to enable the observation of atmospheric features such as oxygen on rocky planets in visible light. UNDERGROUND (Ultra-fast AO techNology Determination for Exoplanet imageRs from the GROUND), a collaboration built in Feb. 2023 at the Optimal Exoplanet Imagers Lorentz Workshop, aims to (1) motivate oxygen detection in Proxima Centauri b and analogs as an informative science case for high-contrast imaging and direct spectroscopy, (2) overview the state of the field with respect to visible exoplanet imagers, and (3) set the instrumental requirements to achieve this goal and identify what key technologies require further development