Greg Cooke

This poster compares 1D and 3D atmospheric models for ozone production across Earth's oxygenated history and for exoplanets such as Proxima Centauri b. It highlights how model dimensionality affects predictions relevant to future observatories including LIFE and HWO. A manuscript describing this work is in preparation; Akhil Kumar is the first author and I supervised the project.

This poster presents the first application of Lotka–Volterra equations to microbial ecology on habitable hycean exoplanets, modelling anoxic bacterial communities in a vertical water column inspired by worlds such as K2-18 b. We find that a wide range of ecological diversity is possible, with surface phototrophs out-competing deeper species, bacteriophages able to trigger ecosystem collapse, and tidally locked oceans potentially supporting more stable but less dense populations. The paper is published in MNRAS.

This poster is based on ongoing work.

This poster uses independent photochemical modeling to assess whether JWST's detections of CH₄ and CO₂ in the habitable-zone sub-Neptune K2-18 b are better explained by a Hycean world or a mini-Neptune scenario. We find that the mini-Neptune interpretation is incompatible with most of the retrieved abundances, while inhabited and uninhabited Hycean scenarios provide better agreement, highlighting how model assumptions such as stellar UV, surface pressure, and albedo strongly shape the interpretation of chemical constraints. The paper is published in the Astrophysical Journal.

This poster is based on ongoing work.

This poster is based on the work that was eventually published in the Astrophysical Journal. A special thanks to Stephanie Zeller for designing the poster.