On the Limitations of the Anomalous Microwave Emission Emissivity
  Many studies of anomalous microwave emission (AME) have computed an AME
emissivity to compare the strength of the AME detected in different regions.
Such a value is usually defined as the ratio between the intensity of the AME
at 1 cm and the thermal dust emission at 100 \mu m. However, as studies of
Galactic dust emission have shown, the intensity of the thermal dust emission
at 100 \mu m is strongly dependent on the dust temperature, which has severe
implications for the AME emissivity defined in this way. In this work, we
illustrate and quantify this effect and find that the AME emissivity decreases
by a factor of 11.1 between dust temperatures of 20 and 30 K. We, therefore,
conclude that computing the AME emissivity relative to the 100 \mu m emission
does not allow for accurate comparisons between the AME observed in different
environments. With this in mind, we investigate the use of other tracers of the
dust emission with which to compute the AME emissivity and we ultimately
conclude that, despite the difficulty in deriving its value, the column density
of the dust would be the most suitable quantity with which to compute the AME
emissivity.
