The Detectability of Kiloparsec Scale Dual AGNs: The Impact of Galactic
  Structure and Black Hole Orbital Properties
  Observational searches for dual active galactic nuclei (dAGNs) at kiloparsec
separations are crucial for understanding the role of galaxy mergers in the
evolution of galaxies. In addition, kpc-scale dAGNs may serve as the parent
population of merging massive black hole (MBH) binaries, an important source of
gravitational waves. We use a semi-analytical model to describe the orbital
evolution of unequal mass MBH pairs under the influence of stellar and gaseous
dynamical friction in post-merger galaxies. We quantify how the detectability
of approximately 40,000 kpc-scale dAGNs depends on the structure of their host
galaxies and the orbital properties of the MBH pair. Our models indicate that
kpc-scale dAGNs are most likely to be detected in gas-rich post-merger galaxies
with smaller stellar bulges and relatively massive, rapidly rotating gas disks.
The detectability is also increased in systems with MBHs of comparable masses
following low eccentricity prograde orbits. In contrast, dAGNs with retrograde,
low eccentricity orbits are some of the least detectable systems among our
models. The dAGNs in models in which the accreting MBHs are allowed to exhibit
radiative feedback are characterized by a significantly lower overall
detectability. The suppression in detectability is most pronounced in gas-rich
merger remnant galaxies, where radiation feedback is more likely to arise. If
so, then large, relatively gas poor galaxies may be the best candidates for
detecting dAGNs.
