  Tidal disruption events (TDEs) of stars by single or binary supermassive
black holes (SMBHs) brighten galactic nuclei and reveal a population of
otherwise dormant black holes. Adopting event rates from the literature, we aim
to establish general trends in the redshift evolution of the TDE number counts
and their observable signals. We pay particular attention to two types of TDEs
which are expected to be observable out to high redshifts, namely (i) jetted
TDEs whose luminosity is boosted by relativistic beaming, and (ii) TDEs around
binary black holes. We show that the brightest (jetted) TDEs are expected to be
produced by massive black hole binaries if the occupancy of intermediate mass
black holes (IMBHs) in low mass galaxies is high. The same binary population
will also provide gravitational wave sources for eLISA. In addition, we find
that the shape of the X-ray luminosity function of TDEs strongly depends on the
occupancy of IMBHs and could be used to constrain scenarios of SMBH formation.
Finally, we make predictions for the expected number of TDEs observed by future
X-ray telescopes as a function of their sensitivity limits. We find that an
instrument which is 50 times more sensitive than the Burst Alert Telescope
(BAT) on board the Swift satellite is expected to trigger ~10 times more events
than BAT with 50% of the events coming from z>2. Because of their long decay
times, high-redshift TDEs can be mistaken for fixed point sources in deep field
surveys such as the 4Ms survey with the Chandra X-ray Observatory and targeted
observations of the same deep field with year-long intervals could reveal TDEs.
If the occupation fraction of IMBHs is high, 6-20 TDEs are expected in each
deep field observed by a telescope 50 times more sensitive than Chandra.

High Energy Astrophysical Phenomena;Cosmology and Nongalactic Astrophysics