A variety of supernova events, including Type IIn supernovae and
ultraluminous supernovae, appear to have lost up to solar masses of their
envelopes in 10's to 100's of years leading up to the explosion. In order to
explain the close timing of the mass loss and supernova events, we explore the
possibility that the mass loss is driven by common envelope evolution of a
compact object (neutron star or black hole) in the envelope of a massive star
and the supernova is triggered by the inspiral of the compact object to the
central core of the companion star. The expected rate of such events is smaller
than the observed rate of Type IIn supernovae but the rates may agree within
the uncertainties. The mass loss velocity is related to the escape velocity
from the common envelope system and is comparable to the observed velocity of
100's of km s−1 in Type IIn events. The mass loss is expected to be denser
near the equatorial plane of the binary system and there is good evidence that
the circumstellar media in Type IIn supernovae are asymmetric. Some of these
supernova types show evidence for energies in excess of the canonical 1051
ergs, which might be the result of explosions from rapid accretion onto a
compact object through a disk.Comment: Small changes to agree with published version: ApJ Letters, 752, L2
(2012