The PAH Revolution: Cold, Dark Carbon at the Earliest Stages of Star Formation

Polycyclic Aromatic Hydrocarbons (PAHs) have been implicated as a large reservoir of reactive carbon in the interstellar medium since the 1980s. PAHs have been widely attributed as the carriers of the unidentified infrared bands where their aggregate vibrational emission spectra are extremely well matched to the observed line signals. Only in the last year have individual PAHs been detected in the ISM for the first time, allowing us to begin to investigate the detailed chemical pathways for the formation and destruction of these molecules. In this talk, I will discuss our detections of PAH molecules via their rotational transitions using Green Bank Telescope observations of TMC-1 from the GOTHAM collaboration. I will present an overview of the methodology, and then dig into our attempts to understand -- and model -- the reactions that produce these species in this cold dark cloud. Finally, I will speculate on what our observations can - or cannot - tell us about the greater role of PAH molecules throughout the star- and planet-forming process.