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Arxiv: AGN Selection and Demographics: A New Age with JWST/MIRI Published: 10/19/2023 12:15:26 AM Updated: 4/17/2024 2:21:54 AM

Paper abstract: Understanding the co-evolution of supermassive black holes (SMBHs) and theirhost systems requires a comprehensive census of active galactic nuclei (AGN)behavior across a wide range of redshift, luminosity, obscuration level andgalaxy properties. We report significant progress with JWST towards this goalfrom the Systematic Mid-infrared Instrument Legacy Extragalactic Survey(SMILES). Based on comprehensive SED analysis of 3273 MIRI-detected sources, weidentify 217 AGN candidates over a survey area of ~34 arcmin^2,including a primary sample of 111 AGNs in normal massive galaxies(M_{*}>10^{9.5}~M_\odot) at z~0--4, an extended sample of 86 AGN {\itcandidates} in low-mass galaxies (M_{*}<10^{9.5}~M_\odot) and a high-zsample of 20 AGN {\it candidates} at z~4--8.4. Notably, about 80\% of ourMIRI-selected AGN candidates are new discoveries despite the extensive pre-JWSTAGN searches. Even among the massive galaxies where the previous AGN search isbelieved to be thorough, 34\% of the MIRI AGN identifications are new,highlighting the impact of obscuration on previous selections. By combining ourresults with the efforts at other wavelengths, we build the most complete AGNsample to date and examine the relative performance of different selectiontechniques. We find the obscured AGN fraction increases from L_{\rm AGN,bol}~10^{10}~L_\odot to 10^{11}~L_\odot and then drops towards higherluminosity. Additionally, the obscured AGN fraction gradually increases fromz~0 to z~4 with most high-z AGNs obscured. We discuss how AGNobscuration, intrinsic SED variations, galaxy contamination, survey depth andselection techniques complicate the construction of a complete AGN sample.