Electromagnetic transients and gravitational waves from white dwarf
  disruptions by stellar black holes in triple systems
  Mergers of binaries comprised of compact objects can give rise to explosive
transient events, heralding the birth of exotic objects which cannot be formed
through single star evolution. Using a large number of direct N-body
simulations, we explore the possibility that a white dwarf (WD) is dynamically
driven to tidal disruption by a stellar-mass black hole (BH) as a consequence
of the joint effects of gravitational wave (GW) emission and Lidov-Kozai
oscillations imposed by the tidal field of a outer tertiary companion orbiting
the inner BH-WD binary. We explore the sensitivity of our results to the
distributions of natal kick velocities imparted to the BH and WD upon
formation, adiabatic mass loss, semi-major axes and eccentricities of the
triples, and stellar mass ratios. We find rates of WD-TDEs in the range
$1.2\times 10^{-3}-1.4$ Gpc$^{-3}$ yr$^{-1}$ for $z\leq 0.1$, rarer than
stellar TDEs in triples by a factor of $\sim 3$--$30$. The uncertainty in the
TDE rates may be greatly reduced in the future using gravitational wave (GW)
observations of Galactic binaries and triples with LISA. WD-TDEs may give rise
to high energy X-ray or gamma-ray transients of duration similar to long
gamma-ray bursts but lacking the signatures of a core-collapse supernova, while
being accompanied by a supernova-like optical transient which lasts for only
days. WD--BH and WD--NS binaries will also emit GWs in the LISA band before the
TDE. The discovery and identification of triple-induced WD-TDE events by future
time domain surveys and/or GWs could enable the study of the demographics of
BHs in nearby galaxies.
