The Continuing Mystery of the Anomalous Microwave Emission

The anomalous microwave emission (AME) is emission in the 20-60 GHz range that is correlated with interstellar dust. Discovered in 1996 by the COBE DMR experiment, the AME is a "foreground" that needs to be removed to study the CMB, but it is also an astrophysical puzzle:  the emission process responsible for the AME remains uncertain.

I will review the observational status of the AME, and the pros and cons of different possible emission mechanisms (e.g., spinning dust, thermal fluctuations in magnetic grain materials) that could be responsible for the AME, the degree to which the AME might be polarized, and future prospects.