Speaker
Description
The far-infrared (FIR) regime offers a unique, dust-penetrating window into AGN activity that is inaccessible to X-ray, optical, and radio surveys. While multi-wavelength approaches have been transformative for unobscured AGN demographics, the heavily obscured population (believed to dominate at cosmic noon) remains poorly characterized. FIR fine-structure lines are powerful obscuration-independent AGN tracers, yet physically-motivated predictions for their emission in AGN-host galaxies are largely absent from the literature. We present predictions for FIR line emission from AGN-host galaxies using SLICK, a multiphase ISM post-processing framework, applied to the IllustrisTNG cosmological simulations. SLICK combines DESPOTIC for the molecular phase with Cloudy for the ionized phase, incorporating AGN radiation fields self-consistently from TNG black hole accretion rates. The framework models the full suite of FIR fine-structure lines such as [OIII] 88µm, [NII] 122/205µm, [CII] 158µm, [OI] 63µm, and the CO ladder, simultaneously across ISM phases, enabling physically-motivated decomposition of line emission into AGN and star-formation contributions. We validate SLICK against observed FIR line luminosities from nearby QSOs and LIRGs to high-z galaxies, and present physically-motivated predictions for AGN-host galaxies across a range of Eddington ratios and redshifts. Our results will inform survey strategy for PRIMA, the proposed FIR probe mission, providing concrete recommendations for line selection and sensitivity requirements to conduct a census of AGN across cosmic time, including the heavily obscured population inaccessible to shorter wavelengths.