First detection of the Sunyaev Zel'dovich effect increment at lambda <
  650 um
  The Sunyaev-Zel'dovich (SZ) effect is a spectral distortion of the cosmic
microwave background as observed through the hot plasma in galaxy clusters.
This distortion is a decrement in the CMB intensity for lambda > 1.3 mm, an
increment at shorter wavelengths, and small again by lambda ~250 um. As part of
the Herschel Lensing Survey (HLS) we have mapped 1E0657-56 (the Bullet cluster)
with SPIRE with bands centered at 250, 350 and 500 um and have detected the SZ
effect at the two longest wavelengths. The measured SZ effect increment central
intensities are Delta I_{0} = 0.097 +- 0.019 MJy sr^{-1} at 350 um and Delta
I_{0} = 0.268 +- 0.031 MJy sr^{-1} at 500 um, consistent with the SZ effect
spectrum derived from previous measurements at 2 mm. No other diffuse emission
is detected. The presence of the finite temperature SZ effect correction is
preferred by the SPIRE data at a significance of 2.1 sigma, opening the
possibility that the relativistic SZ effect correction can be constrained by
SPIRE in a sample of clusters. The results presented here have important
ramifications for both sub-mm measurements of galaxy clusters and blank field
surveys with SPIRE.
