GALACTIC DUST EMISSION AND THE COSMIC MICROWAVE BACKGROUND

In this paper we examine the constraints imposed on observations of Cosmic Microwave Background by the presence of galactic dust emission. In particular, we consider the nature of the dust emission, in terms of grain properties and environment, and the overall galactic emission (especially at high latitudes). The IRAS 100-mu-m survey should provide useful data on which to base estimates of emission at longer wavelengths. However, variations in the dust heating from place to place in the Galaxy, and, should they be found, variations in the dust/gas ratio and grain properties within the Galaxy imply that multi-wavelength coverage and detailed point to point modelling of the galactic dust emission is required if genuine CMB anisotropies are to be observed at far-infrared frequencies. If a new dust component is found which is not correlated with the H I associated dust seen by IRAS, the 100-mu-m data will no longer accurately trace the dust emission at longer wavelengths. Estimates are given of the likely dust contribution to observations by COBE at 90 GHz.