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Arxiv: A Study of Polycyclic Aromatic Hydrocarbon Emission in 30 Dor as seen by JWST Published: 10/24/2024 7:59:41 PM Updated: 10/24/2024 7:59:41 PM

Paper abstract: Polycyclic aromatic hydrocarbons (PAHs) are responsible for strong mid-IRemission features near star-forming regions. It is well known thatlow-metallicity environments exhibit weaker PAH emission, but it is not clearhow the metallicity affects the properties of the emitting PAH population. Wepresent a detailed study of the PAH emission in the low-metallicity regimerepresented by 30 Dor in the Large Magellanic Cloud (LMC) and we compare it tothe PAH emission in the Orion Bar to investigate the characteristics of the PAHpopulation and how the environments affects the resulting IR emission. Weanalyze JWST observations of 30 Dor that include imaging (NIRCam, MIRI) andspectroscopy (NIRSpec/IFU, MIRI/MRS). We extracted NIRSpec/IFU and MIRI/MRSspectra from 18 apertures that cover the morphological structures of 30 Dor. Wecharacterize the profiles and relative intensities of PAH emission in theseapertures. The detailed profiles of the PAH emission bands in 30 Dor are allvery similar, and compare well to those from one of the dissociation fronts(DF2) in the Orion Bar. The relative band ratios on the other hand show a muchlarger range than in the Orion Bar. The PAH emission in 30 Dor originates froma population with a higher ionization fraction than in the Orion Bar, and asize distribution that has more smaller PAHs. Since smaller PAHs typicallyphoto-fragment before larger PAHs, our findings support the hypothesis that thelower PAH emission for lower metallicities is the result of inhibition ofgrowth toward larger PAHs rather than photo-fragmentation.