Binary AGN simulations with radiation pressure reveal a new duty cycle,
  and a reduction of gravitational torque, through 'minitori' structures
  We produce the first set of radiation hydrodynamics simulations of binary
AGNs at parsec-scale separation in scale-model simulations. We use SPH for
hydrodynamics, and raytracing to calculate optical depths and radiation
pressure from the two AGNs. We confirm that, without radiation pressure, the
sign of gravitational torque is sensitive to the binary parameters, although in
one of our two orbital configurations the binary should coalesce in a
time-scale of $<10^9$ yr. However, radiation pressure quickly destroys the
'minitori' around each SMBH, drastically reducing gravitational torques and
accretion, and greatly increasing the coalescence time-scale. Our simulations
suggest a new 'minitorus' duty cycle with a time-scale of ~10 binary periods
(~$10^6$ yr when scaling our models to a total binary mass of
$2\times10^7\,M_\odot$). The growth and blow-out phases of the 'minitori' are
of similar time-scales, and thus we expect about half of observed binary SMBHs
to be active, in at least one component. The 'minitorus' structure provides
asymmetries that could be observed by infrared interferometry.
