  In this paper we compute the radiation of the massless closed string states
due to the non-vanishing coupling to the rolling open string tachyon with
co-dimensions larger than 2, and discuss the effect of back reaction to the
motion of the rolling tachyon. We find that for small string coupling, the
tachyonic matter remains in the late time, but it will completely evaporate
away over a short time of few string scales if the string coupling is huge.
Comment on the implication of our results to the g-theorem of boundary
conformal field theory is given.
