Microwave Interstellar Medium Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust

Abstract

We observe significant dust-correlated emission outside of H II regions in the Green Bank Galactic Plane Survey (-4° < b < 4°) at 8.35 and 14.35 GHz. The rising spectral slope rules out synchrotron and free-free emission as majority constituents at 14 GHz, and the amplitude is at least 500 times higher than expected thermal dust emission. When combined with the Rhodes (2.326 GHz) and Wilkinson Microwave Anisotropy Probe (23-94 GHz) data, it is possible to fit dust-correlated emission at 2.3-94 GHz with only soft synchrotron, free-free, thermal dust, and an additional dust-correlated component similar to Draine & Lazarian spinning dust. The rising component generally dominates free-free and synchrotron for ν gsim 14 GHz and is overwhelmed by thermal dust at ν gsim 60 GHz. The current data fulfill most of the criteria laid out by Finkbeiner and coworkers for detection of spinning dust.