Polycyclic aromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM) of solar metallicity galaxies, where they play a critical role in ISM heating, cooling, and reprocessing stellar radiation. The PAH fraction, the abundance of PAHs relative to total dust mass, is a key parameter in ISM physics. Using JWST and MUSE observations of 42 galaxies from the PHANGS survey, we analyze the PAH fraction in over 17000 HII regions spanning a gas-phase oxygen abundance of 12+log(O/H)=8.0-8.8 (Z~0.2-1.3Z_{sun}_), and ~400 isolated supernova remnants (SNRs). We find a significantly lower PAH fraction toward HII regions compared to a reference sample of diffuse ISM areas at matched metallicity. At 12+log(O/H)>8.2, the PAH fraction toward HII regions is strongly anti-correlated with the local ionization parameter, suggesting that PAH destruction is correlated with ionized gas and/or hydrogen-ionizing UV radiation. At lower metallicities, the PAH fraction declines steeply in both HII regions and the diffuse ISM, likely reflecting less efficient PAH formation in metal-poor environments. Carefully isolating dust emission from the vicinity of optically-identified supernova remnants, we see evidence for selective PAH destruction from measurements of lower PAH fractions, which is, however, indistinguishable at ~50pc scales. Overall, our results point to ionizing radiation as the dominant agent of PAH destruction within HII regions, with metallicity playing a key role in their global abundance in galaxies.

Cone search capability for table J/A+A/703/A103/tabled1 (Catalog with our measurements)