Description
The Great Oxidation Event (GOE) occurred 2.54 billion years ago and transformed the composition of the Early Archean Earth’s atmosphere from being less than 1ppm of O2 to approximately 2% (Catling, et al. 2017). We model the processes behind the GOE by incorporating the complete photochemical network detailed in Liu et al. 2019 with additional reactions describing the process of carbon burial made possible from oxygenic photosynthesis. The main goal of this research is to see how similar processes on exoplanets might be observable through transit spectroscopy. With this work I model with a kinetic equilibrium code, and create synthetic transit depth spectra at different points in the evolution using the petitRadtrans python package. Then, harnessing the tools in petitRadtrans, synthetic transit radii can be created from the model data and compared to current observation. By taking the outputs of the model at different time steps, there is a visible difference in the transit radii produced. Our preliminary results suggested that the most observable difference in the atmospheric composition is the decline in CO2 and CH4 caused by burial of carbon as organic material and consequently the creation of OH. We then expanded our research by increasing the chemical network to include more of the processes affecting the atmospheric O2, in particular the ability to detect O2 via the proxy of O3. Improving our understanding of O2 in the atmosphere might be a crucial next step in the search for complex life outside of Earth, both due to the role of O2 as a biosignature, and because complex life might be more dependent on high energy available in aerobic metabolism (Catling, et al. 2005).
| Field of study | Astrophysics |
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| Supervisor | Uffe G. Jørgensen |