Modeling galactic microwave emission from 0.4 to 50 GHz

Abstract

We have developed a full‐sky model of galactic microwave radiation at frequencies from 0.4 GHz to ≳50 GHz, with a resolution of ∼2°. The primary components are free‐free emission from ionized hydrogen and synchrotron emission from cosmic rays. (Dust emission is negligible in this frequency range.) A variety of data are used to estimate free‐free emission from HII: the galactic plane and adjacent regions come from continuum surveys near 2.7 GHz; emission at higher galactic latitudes is approximated by a cosecant law. The synchrotron component is extrapolated from sky‐survey data at 408 MHz. Both components vary with frequency. This model has been used to derive corrections for galactic emission in our measurements of the low‐frequency CMBR spectrum.