Polycyclic aromatic hydrocarbon luminous galaxies in JWST CEERS data

Abstract

It has been an unanswered question how many dusty galaxies have been undetected from the state-of-the-art observational surveys. JWST enables us to detect faint infrared (IR) galaxies that have prominent polycyclic aromatic hydrocarbon (PAH) features in the mid-IR wavelengths. PAH is a valuable tracer of star formation and dust properties in the mid-IR wavelength. The JWST Cosmic Evolution Early Release Science (CEERS) fields provide us with wavelength coverage from 7.7 to 21 μm using six photometric bands of the mid-IR instrument (MIRI). We have identified galaxies dominated by mid-IR emission from PAHs, termed PAH galaxies. From our multiband photometry catalogue, we selected 10 PAH galaxies displaying high flux ratios of log (S₁₅/S₁₀) > 0.8. The SED fitting analysis indicates that these galaxies are star-forming galaxies with total IR luminosities of 10¹⁰ ~ 10^11.5 L_⊙ at z ~1. The morphology of PAH galaxies does not show any clear signatures of major merging or interaction within the MIRI resolution. The majority of them are on the star-formation main sequence at z ~ 1. Our result demonstrates that JWST can detect PAH emissions from normal star-forming galaxies at z ~ 1, in addition to ultra-luminous infrared galaxies or luminous IR galaxies (LIRGs).