PAH emission from star-forming and quiescent galaxies at z=0.5−0.8 probed by JWST/MIRI

@misc{mondal2026emission,
  title = {{PAH emission from star-forming and quiescent galaxies at $z=0.5-0.8$ probed by JWST/MIRI}},
  author = {Chayan Mondal and Chian-Chou Chen and Kanak Saha and Thomas S. -Y. Lai and Irene Shivaei and Hiddo S. B. Algera and Bovornpratch Vijarnwannaluk},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.06639},
  eprint = {2610.06639},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.06639},
}

TY  - UNPB
TI  - PAH emission from star-forming and quiescent galaxies at z=0.5−0.8 probed by JWST/MIRI
AU  - Chayan Mondal
AU  - Chian-Chou Chen
AU  - Kanak Saha
AU  - Thomas S. -Y. Lai
AU  - Irene Shivaei
AU  - Hiddo S. B. Algera
AU  - Bovornpratch Vijarnwannaluk
PY  - 2026
DA  - 2026/10/05
PB  - arXiv
DO  - 10.48550/arxiv.2610.06639
UR  - https://arxiv.org/abs/2610.06639
AB  - We investigate emission from polycyclic aromatic hydrocarbon (PAH) dust molecules in 224 MIRI-selected star-forming and quiescent galaxies at z=0.5−0.8 in the GOODS-South field using multi-wavelength data from the AstroSat/UVIT, JWST, HST, Herschel, and MUSE. We define an observed diagnostic parameter, f_PAH, as the ratio of JWST/MIRI F1280W to the average of F770W and F2550W band fluxes, and demonstrate that it effectively traces the PAH mass fraction (q_PAH) by capturing 7.7μm PAH emission at our targeted redshift. We observe a bimodal distribution of similar nature in both f_PAH and q_PAH, suggesting that PAH enrichment in galaxies goes through a rapid transition phase from a PAH-poor to a PAH-rich system, at about 70\% solar metallicity. For the star-forming galaxies (SFGs; i.e., ∼78\% of the total sample), we find that f_PAH increases with stellar mass and rest-frame FUV luminosity, identifying massive, UV-bright galaxies to have higher PAH mass fraction. However, the majority of the massive quiescent galaxies (QGs) show lower PAH mass fraction relative to that of SFGs of similar mass, suggesting PAH and smaller dust grains are more susceptible to destruction during quenching processes. Among SFGs, we observe an anti-correlation between f_PAH and the O32 emission line ratio, suggesting PAH photo-dissociation in strongly ionized ISM. This anti-correlation, along with a correlation between f_PAH and gas-phase metallicity 12+log(O/H), indicates that low-mass, metal-poor SFGs, which are increasingly common at even higher redshifts, host more extreme conditions less favorable for PAH production and survival.
ER  -