Long wavelength observations of high galactic latitude dust

Abstract

The properties of high latitude dust are of great interest to extragalactic astronomers and cosmologists. It is proposed here that essentially all high galactic latitude interstellar dust is at a typical temperature of about 20 K (i.e. it is warm dust) and that if any cold interstellar dust exists. its emission at mm wavelengths is less than 5%, of that from the primary component of warm dust observed by IRAS. Thus. the IRAS maps reveal the high latitude dust of import. The crucial issue is how the emissivity of the dust scales with wavelength. The mm wavelength emission in this warm dust-only model is consistent with roughly a wavelength-dependent emissivity ϵ( λ)∞ λ −1.5. Such a dependence has been observed previously in the IR. What is new here is the proposal that this extends to the mm wavelength region.