A new census of dust and PAHs at z=0.7-2 with JWST MIRI
arxiv(2024)
摘要
This paper utilizes the JWST MIRI multi-band imaging data from the SMILES
survey (5-25micron), complemented with HST and NIRCam photometric and
spectroscopic 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 to
a new mass and SFR parameter space beyond our local universe. We find a strong
correlation between the fraction of dust in PAHs (PAH fraction, q_PAH) with
stellar mass. Moreover, the PAH fraction behavior as a function of gas-phase
metallicity is similar to that at z 0 from previous studies, suggesting a
universal relation: q_PAH is constant ( 3.4
0.5Z_⊙ and decreases to <1
indicates that metallicity is a good indicator of the ISM properties that
affect the balance between the formation and destruction of PAHs. The lack of a
redshift evolution from z 0-2 also implies that above 0.5 Z_⊙, the PAH
emission effectively traces obscured luminosity and the previous
locally-calibrated PAH-SFR calibrations remain applicable in this metallicity
regime. We observe a strong correlation between obscured UV luminosity fraction
(ratio of obscured to total luminosity) and stellar mass. Above the stellar
mass of >5× 10^9M_⊙, on average, more than half of the emitted
luminosity is obscured, while there exists a non-negligible population of lower
mass galaxies with >50
fraction correlates with SFR surface density. This is a result of higher dust
covering fractions in galaxies with more compact star forming regions.
Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UV
continuum slope tend to have higher SFR surface density and shallower
attenuation curves, owing to their higher effective dust optical depths and
more compact star forming regions.
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