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Arxiv: A new census of dust and polycyclic aromatic hydrocarbons at z=0.7-2 with JWST MIRI Published: 2/12/2024 9:00:20 PM Updated: 9/8/2024 8:21:49 PM

Paper abstract: This paper utilizes the JWST MIRI multi-band imaging data from the SMILESsurvey (5-25micron), complemented with HST and NIRCam photometric andspectroscopic data from the JADES and FRESCO surveys for 443 star-forming(non-AGN) galaxies at z=0.7-2.0 to extend the study of dust and PAH emission toa new mass and SFR parameter space beyond our local universe. We find a strongcorrelation between the fraction of dust in PAHs (PAH fraction, q_PAH) withstellar mass. Moreover, the PAH fraction behavior as a function of gas-phasemetallicity is similar to that at z~0 from previous studies, suggesting auniversal relation: q_PAH is constant (~3.4%) above a metallicity of ~0.5Z_{\odot} and decreases to <1% at metallicities <0.3Z_{\odot}. Thisindicates that metallicity is a good indicator of the ISM properties thataffect the balance between the formation and destruction of PAHs. The lack of aredshift evolution from z~0-2 also implies that above 0.5\,Z_{\odot}, the PAHemission effectively traces obscured luminosity and the previouslocally-calibrated PAH-SFR calibrations remain applicable in this metallicityregime. We observe a strong correlation between obscured UV luminosity fraction(ratio of obscured to total luminosity) and stellar mass. Above the stellarmass of >5\times 10^9M_{\odot}, on average, more than half of the emittedluminosity is obscured, while there exists a non-negligible population of lowermass galaxies with >50% obscured fractions. At a fixed mass, the obscuredfraction correlates with SFR surface density. This is a result of higher dustcovering fractions in galaxies with more compact star forming regions.Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UVcontinuum slope tend to have higher SFR surface density and shallowerattenuation curves, owing to their higher effective dust optical depths andmore compact star forming regions.