Uniqueness of G+0.693’s chemical complexity

Determine whether the extraordinary chemical complexity observed in the G+0.693-0.027 molecular cloud is unique or instead a common outcome of shock-driven chemistry.

Background

The G+0.693-0.027 molecular cloud in the Sgr B2 complex is one of the richest molecular reservoirs known in the interstellar medium. Its moderate gas temperatures, widespread subthermal excitation, and low-velocity shocks associated with large-scale cloud–cloud collisions facilitate the detection of weak molecular transitions and enhance gas-phase molecular abundances through the release of molecules from icy grain mantles.

Before the characterization of G+0.633-0.0604, the remarkable molecular inventory of G+0.693—including numerous complex organic and prebiotic molecules—could have represented either an exceptional local circumstance or a more general consequence of shock-driven chemistry. The paper explicitly identifies determining whether this chemical richness is unique as an unresolved question; its subsequent discussion of G+0.633 provides evidence that the richness is not unique, but the quoted passage presents the question as open at that point in the paper.