GBT25B-096

ARKHAM Knights: The Fate of Dark Aromatic Carbon in PDRs

Abstract

The life cycle of carbon in the universe is dominated by polycyclic aromatic hydrocarbons (PAHs). From the diffuse ISM, to stellar birth and death, PAHs are ubiquitous, however, until recently PAHs had not been directly detected. The GOTHAM team has now unambiguously detected several individual PAHs in the dark molecular cloud TMC-1, opening up the ability to understand their formation pathways. While we have evidence for PAHs at all stages of stellar growth, it is still unclear both whether the PAHs we see in dark clouds and planetary bodies form via ``bottom-up'' (small hydrocarbons combining) or ``top-down'' (fracturing of large PAHs or grains) pathways and what their ultimate fate is beyond the dark cloud phase. The observations proposed here of the Horsehead Nebula photodissociation region will allow us to understand how well small PAHs survive in harsh UV conditions and help to determine whether inherited PAHs can indeed survive the harsh conditions of the diffuse ISM or if they are easily destroyed and thus must reform in cold, dark clouds. The result of this investigation will challenge the current understanding of PAH formation in the most extreme astronomical environments.

Investigators

Name	Institution
Andrew Lipnicky *	National Radio Astronomy Observatory; Rochester Institute of Technology
Ilsa Cooke	British Columbia, University of; Rennes 1, Université de
Gabi Wenzel	Massachusetts Institute of Technology
Brett McGuire	National Radio Astronomy Observatory; Massachusetts Institute of Technology
Tony Remijan	National Radio Astronomy Observatory
Reace Willis	British Columbia, University of

* indicates the PI