| Abstract |
We present maps tracing the fraction of dust in the form of polycyclic aromatic hydrocarbons (PAHs) in IC 5332, NGC 628, NGC 1365, and NGC 7496 from JWST/MIRI observations. We trace the PAH fraction by combining the F770W ($7.7~\mu$m) and F1130W ($11.3~\mu$m) filters to track ionized and neutral PAH emission, respectively, and comparing the PAH emission to F2100W which traces small, hot dust grains. We find average $R{\rm_{PAH} = (F770W+F1130W)/F2100W}$ values of 3.3, 4.7, 5.1, and 3.6 in IC 5332, NGC 628, NGC 1365, and NGC 7496, respectively. We find that H II regions traced by MUSE H$\alpha$ show a systematically low PAH fraction. The PAH fraction remains relatively constant across other galactic environments, with slight variations. We use CO + H I + H$\alpha$ to trace the interstellar gas phase and find that the PAH fraction decreases above a value of I$_{H\alpha}/\Sigma_{H~I+H_2}$ $\sim~10^{37.5}$ erg s$^{-1}$ kpc$^{-2}$ (M$_\odot$ pc$^{-2}$)$^{-1}$, in all four galaxies. Radial profiles also show a decreasing PAH fraction with increasing radius, correlated with lower metallicity, in line with previous results showing a strong metallicity dependence to the PAH fraction. Our results suggest that the process of PAH destruction in ionized gas operates similarly across the four targets. |
| Authors |
Jérémy Chastenet  , Jessica Sutter , Karin Sandström , Francesco Belfiore , Oleg V. Egorov , Kirsten L. Larson , Adam K. Leroy , Daizhong Liu , Erik Rosolowsky , David A. Thilker , Elizabeth J. Watkins , Thomas G. Williams , Ashley T. Barnes , Frank Bigiel , M. Boquien , Mélanie Chevance , I-Da Chiang , Daniel A. Dale  , J. M. Diederik Kruijssen , Éric Emsellem , Kathryn Grasha , Brent Groves , Hamid Hassani , Annie Hughes , Kathryn Kreckel , Sharon E. Meidt , Ryan J. Rickards Vaught , Amy Sardone , E. Schinnerer
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