Self-Consistent Grain Depletions and Abundances II: Effects on strong-line diagnostics of extragalactic H II regions

Chamani M. Gunasekera, Xihan Ji, Marios Chatzikos, Renbin Yan, Gary Ferland

Published 2022-05-25Version 1

The depletion of elements onto dust grains is characterized using a generalized depletion strength $F_*$ for any sightline, and trend-line parameters $A_X, B_X$ and $z_X$. The present study uses these parameters to calculate post-depleted gas-phase abundances of 15 different elements while varying $F_*$ from 0 to 1 in increments of 0.125. An analysis of emergent strong spectral line intensities, obtained by inputting the calculated abundances into a CLOUDY model, shows that the depletion strength has a non-trivial effect on predicted emission lines and the thermal balance of the ionized cloud. The depleted elements not only affect the abundance of corresponding ions but also affects the balance of coolant abundances in the gas. Furthermore, it was found that each of the parameters - metallicity, ionization parameter $U$ and depletion strength $F_*$ work in tandem to affect the emission-line strengths, and thermal balance of the ISM. Finally, comparing our results to a sample of H II regions using data obtained from the MaNGA survey revealed that the best-fit $F_*$ was approximately 0.5. This best-fit value does not work well for all metallicities, and it may be due to Sulfur depletion.