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Active Galactic Nuclei Selection and Demographics: A New Age with JWST/MIRI

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jats:titleAbstract</jats:title> jats:pUnderstanding the coevolution of supermassive black holes and their host systems requires a comprehensive census of active galactic nuclei (AGNs) behavior across a wide range of redshift, luminosity, obscuration level, and galaxy properties. We report significant progress with JWST toward this goal from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES). Based on comprehensive spectral energy distribution (SED) analysis of 3273 MIRI-detected sources, we identify 217 AGN candidates over a survey area of ∼34 arcminjats:sup2</jats:sup>, including a primary sample of 111 AGNs in normal massive galaxies (jats:italicM</jats:italic> jats:sub</jats:sub> > 10jats:sup9.5</jats:sup> jats:italicM</jats:italic> jats:sub☉</jats:sub>) at jats:italicz</jats:italic> ∼ 0–4, an extended sample of 86 AGN jats:italiccandidates</jats:italic> in low-mass galaxies (jats:italicM</jats:italic> jats:sub</jats:sub> < 10jats:sup9.5</jats:sup> jats:italicM</jats:italic> jats:sub☉</jats:sub>), and a high-jats:italicz</jats:italic> sample of 20 AGN jats:italiccandidates</jats:italic> at jats:italicz</jats:italic> ∼ 4–8.4. Notably, about 80% of our MIRI-selected AGN candidates are new discoveries despite the extensive pre-JWST AGN searches. Even among the massive galaxies where the previous AGN search is believed to be thorough, 34% of the MIRI AGN identifications are new, highlighting the impact of obscuration on previous selections. By combining our results with the efforts at other wavelengths, we build the most complete AGN sample to date and examine the relative performance of different selection techniques. We find the obscured AGN fraction increases from jats:italicL</jats:italic> jats:subAGN,bol</jats:sub> ∼ 10jats:sup10</jats:sup> jats:italicL</jats:italic> jats:sub⊙</jats:sub> to 10jats:sup11</jats:sup> jats:italicL</jats:italic> jats:sub⊙</jats:sub> and then drops toward higher luminosity. Additionally, the obscured AGN fraction gradually increases from jats:italicz</jats:italic> ∼ 0 to jats:italicz</jats:italic> ∼ 4 with most high-jats:italicz</jats:italic> AGNs obscured. We discuss how AGN obscuration, intrinsic SED variations, galaxy contamination, survey depth, and selection techniques complicate the construction of a complete AGN sample.</jats:p>



5106 Nuclear and Plasma Physics, 51 Physical Sciences

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American Astronomical Society
NASA ∣ GSFC ∣ Astrophysics Science Division (ASD) (NNX13AD82G)
NASA ∣ Jet Propulsion Laboratory (JPL) (1255094)
EC ∣ European Research Council (ERC) (789056)
Spanish Ministerio de Ciencia e Innovación MCIN/AEI (PID2022-139567NB-I00)
NASA ∣ Goddard Space Flight Center (GSFC) (NAS5-02105)