The secular tidal disruption of stars by low-mass Super Massive Black
  Holes secondaries in galactic nuclei
  Stars passing too close to a super massive black hole (SMBH) can produce
tidal disruption events (TDEs). Since the resulting stellar debris can produce
an electromagnetic flare, TDEs are believed to probe the presence of single
SMBHs in galactic nuclei, which otherwise remain dark. In this paper, we show
how stars orbiting an IMBH secondary are perturbed by an SMBH primary. We find
that the evolution of the stellar orbits are severely affected by the primary
SMBH due to secular effects and stars orbiting with high inclinations with
respect to the SMBH-IMBH orbital plane end their lives as TDEs due to
Kozai-Lidov oscillations, hence illuminating the secondary SMBH/IMBH. Above a
critical SMBH mass of $\approx 1.15 \times 10^8$ M$_{\odot}$, no TDE can occur
for typical stars in an old stellar population since the Schwarzschild radius
exceeds the tidal disruption radius. Consequently, any TDEs due to such massive
SMBHs will remain dark. It follows that no TDEs should be observed in galaxies
with bulges more massive than $\approx 4.15\times 10^{10}$ M$_{\odot}$, unless
a lower-mass secondary SMBH or IMBH is also present. The secular mechanism for
producing TDEs considered here therefore offers a useful probe of
SMBH-SMBH/IMBH binarity in the most massive galaxies. We further show that the
TDE rate can be $\approx 10^{-4}-10^{-3}$ yr$^{-1}$, and that most TDEs occur
on $\approx 0.5$ Myr. Finally, we show that stars may be ejected with
velocities up to thousands of km s$^{-1}$, which could contribute to the
observed population of Galactic hypervelocity stars.
