ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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The detectability and constraints of biosignature gasses in the near & mid-infrared from transit transmission spectroscopy

Description
The James Webb Space Telescope (JWST) is expected to revolutionize the current understanding of Jovian worlds over the coming decade. However, as the field pushes towards characterizing cooler, smaller, “terrestrial-like” planets, dedicated next-generation facilities will be required to tease out the small spectral signatures indicative of biological activity. Here, the…

The James Webb Space Telescope (JWST) is expected to revolutionize the current understanding of Jovian worlds over the coming decade. However, as the field pushes towards characterizing cooler, smaller, “terrestrial-like” planets, dedicated next-generation facilities will be required to tease out the small spectral signatures indicative of biological activity. Here, the feasibility of determining atmospheric properties, from near to mid-infrared transmission spectra, of transiting temperate terrestrial M-dwarf companions, has been evaluated. Specifically, atmospheric retrievals were utilized to explore the trade space between spectral resolution, wavelength coverage, and signal-to-noise on the ability to both detect molecular species and constrain their abundances. Increasing spectral resolution beyond R=100 for near-infrared wavelengths, shorter than 5um, proves to reduce the degeneracy between spectral features of different molecules and thus greatly benefits the abundance constraints. However, this benefit is greatly diminished beyond 5um as any overlap between broad features in the mid-infrared does not deconvolve with higher resolutions. Additionally, the inclusion of features beyond 11um did not meaningfully improve the detection significance nor abundance constraints results. The findings of this study indicate that an instrument with continuous wavelength coverage from approximately 2-11um and with a resolution of R~50-300, would be capable of detecting H2O, CO2, CH4, O3, and N2O in the atmosphere of an Earth-analog transiting an M-dwarf (magK=8.0) within 50 transits, and obtain better than an order-of-magnitude constraint on each of their abundances.

The Origins Space Telescope (Origins) is one of four flagship mission concepts, under review by the 2020 Decadal Survey, that may take the mantle of the next-generation space-based observatory. In conjunction with this research, a secondary trade space study was performed on behalf of the Origins Exoplanets Working Group. The primary purpose of this collaboration was to provide a scientific basis to the technical specifications for the mid-infrared detectors onboard the Mid-Infrared Spectrometer Camera Transit Spectrometer (MISC-T) instrument. The results of this work directly contributed to the alteration of the official technical specifications of the instrument design concept.
ContributorsTremblay, Luke (Author) / Line, Michael R (Thesis advisor) / Schkolnik, Evgenya (Committee member) / Walker, Sarah (Committee member) / Arizona State University (Publisher)
Created2019