JWST MIRI color classification of mid-infrared selected galaxies: MIRI color classification toward cosmic noon

TL;DR

This study develops a redshift-dependent mid-infrared galaxy classification method using JWST MIRI colors, effectively distinguishing AGN, star-forming, and silicate absorption galaxies up to z~2, based on synthetic photometry and survey data.

Contribution

The paper introduces a novel MIRI color classification tool for high-redshift galaxies, utilizing synthetic photometry from a large MIR spectral database and applying it to JWST survey data.

Findings

Successfully separates galaxy types up to z~2 using MIRI colors.

Identifies galaxies with IR luminosities of 10^{9.2} to 10^{11.9} L_sun at z~1.

First detection of deep silicate absorption in z~1 galaxies.

Abstract

We investigated the James Webb Space Telescope photometric color classification of mid-infrared (MIR) selected galaxies at high redshifts, toward cosmic noon. The aim of the present work is to obtain a z-dependent mid-infrared (MIR) photometric galaxy classification tool based on broad spectral emission and absorption lines using the JWST Mid-Infrared Instrument (MIRI) and its broadband filters. We used the largest Spitzer MIR spectral database to obtain synthetic photometry in the JWST/MIRI filters. We formed MIRI filter combinations to trace the strong polycyclic aromatic hydrocarbon (PAH) emission features and the 9.7 micron silicate feature in seven redshift windows from z = 0.25-2.10. Results. We present z-dependent MIRI color-color plots that separate active galactic nuclei (AGN), star-forming galaxies (SFGs), and silicate absorption-dominated galaxies up to z$\sim$2. We applied the photometric MIR colors to the largest ($\sim$34 arcmin square) MIRI survey called the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES), to identify AGN, SFGs, and Si-absorption dominated galaxies out to substantial redshifts. Our JWST/MIRI SFGs sample includes galaxies with total IR luminosities of $10^{9.2} \sim 10^{11.9} L_{\odot}$ at 0.9 $\leq$z < 1.57. The majority of them are consistent with the z$\sim$1 main sequence. We also identified the first examples of z$\sim$1 galaxies with deep silicate absorption.