New Methods for the Detection and Characterization of Exoplanets

Citation

Llop-Sayson, Jorge Domingo (2022) New Methods for the Detection and Characterization of Exoplanets. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/sxz3-d927. https://resolver.caltech.edu/CaltechTHESIS:04052022-230213679

Abstract

Advancements in detection technologies have allowed the discovery of thousands of exoplanets. These discoveries have revolutionized our understanding of the Universe; not only are planets ubiquitous, but the planetary systems they populate are as diverse as the complex processes that govern their formation allow. This thesis compiles several studies on the development and application of exoplanet detection and characterization methods, in particular for direct imaging and spectroscopy. From all the planets discovered to date, only a marginal portion have been imaged. This is due to the limited access of high contrast instruments into the parameter space where most exoplanets habitate. Developments in high contrast are key to reaching a full understanding of the exoplanet population. In particular, direct methods allow for an effective characterization of the atmospheric compositions, making it possible to probe exoplanet atmospheres in search of biosignatures.

A sure pathway to enhance exoplanet characterization capabilities is by taking full advantage of synergies between detection methods. In Chapter 2 these synergies are explored in the context of ε Eridani's elusive companion: three different methods are combined to constrain its mass and orbital parameters. Combining astrometry, radial velocity, and direct imaging data offers a complementarity that enhances the overall constraining power. In Chapter 3, the α Centauri system is reviewed regarding the possibility of imaging an exoplanet with the JWST observatory in the infrared. The following chapters deal with technological development for high contrast imaging and spectroscopy instruments. In Chapter 4 a coronagraph design study is presented in which new design tools are discussed and evaluated, demonstrating better coronagraph performance. In this chapter the case study is the Nancy Grace Roman Space Telescope Coronagraph Instrument, in which its heavily obstructed pupil constitutes a huge challenge for coronagraph design. Along the same lines, Chapter 5 presents the technology demonstration of the apodized vortex coronagraph (AVC). The AVC is a coronagraph concept that effectively deals with the telescope pupil discontinuities. Chapters 6 and 7 introduce a novel wavefront sensing and control algorithm for the high contrast concept of a fiber injection unit in the image plane of a coronagraph. A single mode fiber (SMF) is placed in the position of the planet to extract its light and feed it into a spectrograph. Our algorithm leverages the synergies of the coronagraph and the mode selectivity of the SMF to maximize the signal-to-noise ratio of the planet.

Thesis Files