The Submm and mm Excess of the SMC: Magnetic Dipole Emission from Magnetic Nanoparticles?

Understand

The Small Magellanic Cloud (SMC) has surprisingly strong submm and mm-wavelength emission that is inconsistent with standard dust models, including those with emission from spinning dust.

• Here we show that the emission from the SMC may be understood if the interstellar dust mixture includes magnetic nanoparticles, emitting magnetic dipole radiation resulting from thermal fluctuations in the magnetization.
• The magnetic grains can be metallic iron, magnetite Fe3O4, or maghemite gamma-Fe2O3.
• The required mass of iron is consistent with elemental abundance constraints.