Institute for Advanced Study Astrophysics Seminar

The search for signs of life beyond Earth is a key motivator in exoplanet research.  A suitable “biosignature gas” is one that: can accumulate in an atmosphere against atmospheric radicals and other sinks; has strong atmospheric spectral features; and has limited abiological false positives. We now have a long list of potential biosignature gases and a quantitative framework to assess them. The successfully operational JWST provides unprecedented data quality and thus high anticipation for identification of exoplanet atmosphere biosignature gases. We are, however, now confronted with two severe practical challenges. First, tiny signals from small exoplanet atmospheres and the underlying highly averaged atmospheric information means we have to resort to statistical inference. Second, M dwarf host stars’ magnetic activity contaminates exoplanet transmission spectroscopy, sometimes on the order of the expected atmospheric spectral features. I will review the JWST state-of-the art triumphs, trials, and tribulations for a reality check on the future of exoplanet biosignature gases. Our pace and history of milestone discovery in exoplanets in the last three decades, combined with new telescope paradigms, promises to eventually deliver on finding signs of life beyond Earth.