Speaker
Description
The search for atmospheric technosignature gases using high-resolution spectroscopy in the near-infrared is a valuable extension of the search for general biosignatures and low-abundance gases in exoplanet atmospheres. High-resolution cross-correlation spectroscopy (HRCCS) is the best technique currently available for this, since it can disentangle faint potential technosignatures from features of more significant atmospheric constituents, such as H$_2$O, and use the light-collecting power of the Extremely Large Telescopes. My research explores the viability of searching for technosignature gases with next-generation, high-resolution spectrographs, such as METIS/ELT, setting realistic expectations on the likelihood of being able to detect these gases on nearby exoplanets, as a function of their concentration. In this talk, I will present a simulation pipeline that can model retrievals of technosignature and other low-abundance gases on rocky exoplanets with the ELT. I use this pipeline to simulate a search for sulphur hexafluoride (SF$_6$), which has potential to exist as an industrial pollutant, and as an intentionally released artificial greenhouse gas on planets with insufficient natural CO$_2$ production. SF$_6$ is nontoxic, relatively chemically inert, and has an atmospheric lifetime of ~1000 years, making it a prime technosignature target. During this talk, I will demonstrate the challenges in HRCCS that need to be addressed for this technosignature search, including the required spectral resolution and light-collecting power, the availability of detailed and accurate line lists, and the trade-offs between wavelength coverage and background thermal noise, when considering observations from ground and space e.g JWST, the ELTs, and the Habitable Worlds Observatory.
