Observation of Hawking radiation Is it conceivable that Hawking radiation could be observed using e.g. gravitational waves or imprints in the CMB?
 A: I don't believe anyone would go looking for Hawking radiation at LIGO or Planck when the energetics suggest (Ukwatta et al (2010)) $\gamma$-ray emissions could be observed with Fermi space telescope.
Further, from the introduction to the Wikipedia entry on Hawking radiation,

In June 2008, NASA launched the Fermi space telescope, which is searching for the terminal gamma-ray flashes expected from evaporating primordial black holes. In the event that speculative large extra dimension theories are correct, CERN's Large Hadron Collider may be able to create micro black holes and observe their evaporation. No such micro black hole has ever been observed at CERN.

So it seems to me that there are better-suited observatories than LIGO or Planck for observational evidence.
Note that a similar question was asked over at Astronomy.SE several years ago where they link to an experimental research of an analog to Hawking radiation that was detected (also mentioned in the Wikipedia entry linked above).
