Infrared emission from tidal disruption events --- probing the pc-scale
  dust content around galactic nuclei
  Recent UV-optical surveys have been successful in finding tidal disruption
events (TDEs), in which a star is tidally disrupted by a supermassive black
hole (BH). These TDEs release a huge amount of radiation energy ~ 10^51-52 erg
into the circum-nuclear medium. If the medium is dusty, most of the radiation
energy will be absorbed by dust grains within ~ 1 pc from the BH and
re-radiated in the infrared. We calculate the dust emission lightcurve from a
1-D radiative transfer model, taking into account the time-dependent heating,
cooling and sublimation of dust grains. We show that the dust emission peaks at
3-10 microns and has typical luminosities ~ 10^42-43 erg/s (with sky covering
factor of dusty clouds ranging from 0.1-1). This is detectable by current
generation of telescopes. In the near future, James Webb Space Telescope will
be able to perform photometric and spectroscopic measurements, in which
silicate or polycyclic aromatic hydrocarbon (PAH) features may be found.
  Observations at rest-frame wavelength > 2 microns have only been reported
from two TDE candidates, SDSS J0952+2143 and Swift J1644+57. Although
consistent with the dust emission from TDEs, the mid-infrared fluxes of the two
events may be from other sources. Long-term monitoring is needed to draw a firm
conclusion. We also point out two nearby TDE candidates (ASSASN-14ae and -14li)
where the dust emission may be currently detectable. The dust infrared emission
can give a snapshot of the pc-scale dust content around weakly- or non-active
galactic nuclei, which is hard to probe otherwise.
