The Diagnostic Potential of JWST in Characterizing Elusive AGNs
  It is now clear that a significant population of accreting black holes are
undetected by commonly employed optical, mid-infrared color, X-ray, and radio
selection methods due to obscuration or contamination of the emission from the
nuclear region caused by star formation in the host galaxy. These elusive
active galactic nuclei (AGNs) are an important component of the AGN population.
They are often found in mergers, where significant black hole growth likely
takes place, and in the lowest mass galaxies or galaxies that lack classical
bulges, a demographic that places important constraints on models of
supermassive black hole seed formation and merger-free models of AGN fueling.
In this work, we demonstrate the power of James Webb Space Telescope (JWST) in
uncovering and characterizing these elusive AGNs. We present an integrated
modeling approach in which both the line and emergent continuum is predicted
from gas exposed to the ionizing radiation from a young starburst and an AGN,
focusing specifically on the spectral diagnostics available through JWST, and
provide predictions on the detectability of key diagnostic lines by the NIRSpec
and MIRI spectrometers, assuming typical conditions for the gas. We demonstrate
the crucial need for JWST in uncovering low level accretion activity even in
nearby galaxies and out to redshifts of ~ 1 - 3, depending on the ionization
parameter, and gas phase metallicity. We present a redshift-dependent selection
strategy that can be used to identify promising elusive AGN candidates for
future follow-up study. The full suite of simulations are available online,
where users can select specific parameters and retrieve the predicted continuum
and infrared line luminosities from our models.
