期刊
ASTROPHYSICAL JOURNAL
卷 757, 期 1, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/0004-637X/757/1/103
关键词
dust, extinction; infrared: galaxies; infrared: ISM; Magellanic Clouds; polarization; radiation mechanisms: thermal; radio continuum: ISM
资金
- NSF [AST 1008570]
- NSF Graduate Research Fellowship [DGE-0646086]
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1008570] Funding Source: National Science Foundation
The Small Magellanic Cloud (SMC) has surprisingly strong submillimeter- and millimeter-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. The magnetic dipole emission is predicted to be polarized orthogonally to the normal electric dipole radiation if the nanoparticles are inclusions in larger grains. We speculate that other low-metallicity galaxies may also have a large fraction of the interstellar Fe in magnetic materials.
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