Diffusion Damping - Effects - The Silk Scale and The Silk Mass

The Silk Scale and The Silk Mass

Diffusion damping exponentially decreases anisotropies in the CMB on a scale (the Silk scale) much smaller than a degree, or smaller than approximately 3 megaparsecs. This angular scale corresponds to a multipole moment . The mass contained within the Silk scale is the silk mass. Numerical evaluations of the Silk mass yield results on the order of solar masses at recombination and on the order of the mass of a present-day galaxy or galaxy cluster in the current era.

As diffusion damping works at this level, scientists say it affects small angles and corresponding anisotropies. This is to be contrasted with other effects which operate on a scale called intermediate or large . Searches for anisotropies on a small scale are not as difficult as those on larger scales, partly because they may employ ground-based telescopes and their results can be more easily predicted by current theoretical models.