Spinning dust

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In astronomy, spinning dust is a mechanism proposed to explain anomalous microwave emission from the Milky Way. The emission could arise from the electric dipole of very rapidly spinning (10–60 GHz) extremely small (nanometer) dust grains (Draine & Lazarian 1998). The anomalous emission was first discovered as a by-product of Cosmic Microwave Background observations which make very sensitive measurements of the microwave sky which have to identify and remove contamination from the galaxy.

History

Anomalous microwave emission was first seen as a surprising statistical correlation of microwave sky variations with far infrared (FIR) emission (Kogut et al. 1996, Leitch et al. 1997). This signal traced the warm galactic dust emission which was unexpected as the extrapolated infrared dust signal to microwave frequencies should have been at least an order of magnitude lower than that seen. Kogut et al. had correlated COBE Differential Microwave Radiometer observations at centimeter wavelengths with DIRBE dust emission at 140 μm, while Leitch et al. had correlated Owens Valley Radio Observatory ring observations at 14.5 and 32 GHz with IRAS 100 μm. The suggestion at the time was the correlation was due to free-free or Bremsstrahlung emission from ionized gas caused by young hot stars which are formed in these dusty regions.

References

Draine, B. T., & Lazarian, A. 1998a, ApJ, 494, L19
Kogut, A., Banday, A. J., Bennett, C. L. et al. 1996, ApJ, 464, L5
Leitch, E. M., Readhead, A. C. S., Pearson, T. J., & Myers, S. T. 1997, ApJ, 486

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