Mid-IR luminosity functions: inferred dusty cosmic star-formation and black hole accretion histories from the JWST SMILES

Abstract

Mid-infrared (mid-IR) observations are crucial for understanding galaxy evolution, tracing star formation, and active galactic nuclei (AGN) activity via dust emission. This work presents mid-IR galaxy luminosity functions (LFs) at $0.5 < z < 6$, derived from the JWST Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) program. We combine 8 MIRI bands ($5-25$ $\mu$m) of SMILES and archival 23-band HST+JWST NIRCam photometry to construct an extensive catalog containing 2,813 galaxies with sub-$\mu$Jy level completeness in the mid-IR. We obtain monochromatic (in 5.6, 7.7, 10, 12.8, 15, 18, 21, and 25.5 $\mu$m), $L_{\rm IR}$, and AGN LFs, with a limiting luminosity down to $10^{9.5}$ $L_\odot$ at $z=0.5-1.0$, $\sim10^{10.5}$ $L_\odot$ at $z=2.0-4.0$, and to $\sim10^{11}$ $L_\odot$ at $z=4.0-6.0$. With the unprecedented sensitivity and resolution of JWST, here we better constrain the faint-end slope and its evolution of the mid-IR LFs, quantifying the dusty cosmic star formation and black hole accretion histories out to $z \sim 5$. These results provide essential insights to refine our understanding of the obscured star formation and galaxy-AGN co-evolution over cosmic time.