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Magnetic Dipole Emission from Magnetic Grain Materials
If interstellar grains contain magnetic materials, thermal fluctuations in
the magnetization will result in magnetic dipole emission
(Draine & Lazarian 1999a).
The predicted emission is shown in Figure 1 for various
assumptions: 100% of the Fe in paramagnetic amorphous silicate mineral;
100% of the Fe locked up in magnetite (Fe3O4);
or 5% of the Fe present in small metallic iron particles, either bare
ellipsoids or inclusions within silicate grains.
Also shown are observational data points for microwave emission correlated
with 100m thermal emission from interstellar dust, in terms of
microwave emissivity per H nucleon (see Draine & Lazarian 1999a,b).
Figure 1:
Emissivity per H atom due to magnetic dipole emission from
possible magnetic grain materials, plus the low-frequency tail of the
``vibrational emission'' from the overall grain population,
for an assumed emissivity . See Draine & Lazarian (1999b)
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References
- de Oliveira-Costa, et al. 1997, Astrophys. J. (Letters),
482, L17
- de Oliveira-Costa, A., Tegmark, M., Page, L.A., & Boughn, S.P.
1998, Astrophys. J. (Letters), 509, L9
- Draine, B.T., & Lazarian, A. 1999a,
Astrophys. J., 512, 740-754.
- Draine, B.T., & Lazarian, A. 1999b,
in Microwave Foregrounds,
ed. A. de Oliveira-Costa & M. Tegmark (San Francisco: Astr. Soc.
Pacific)].
- Kogut, A., et al. 1996b, Astrophys. J. (Letters),
464, L5
- Leitch, E.M., Readhead, A.C.S., Pearson, T.J., & Myers, S.T.
1997, Astrophys. J. (Letters), 486, L23
- Lim, M.A., et al. 1996, Astrophys. J. (Letters),
469, L69
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Bruce Draine
3/16/1999