Cosmic Amorphous Dust Model as the Origin of Anomalous Microwave Emission

Cosmic Amorphous Dust Model as the Origin of Anomalous Microwave Emission

We have shown that the thermal emission of the amorphous dust composed of amorphous silicate dust (a-Si) and amorphous carbon dust (a-C) provides an excellent fit both to the observed intensity and the polarization spectra of molecular clouds. The anomalous microwave emission (AME) originates from t...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2020-09, Vol.900 (2), p.L40
Main Authors: Nashimoto, Masashi, Hattori, Makoto, Poidevin, Frédérick, Génova-Santos, Ricardo
Format: Article
Language:eng
Subjects:
Clouds
Cosmic dust
Cosmic microwave background radiation
Dust
Interstellar dust
Interstellar matter
Microwave emission
Molecular clouds
Polarization
Radio continuum emission
Silicon
Submillimeter waves
Temperature dependence
Thermal emission
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Summary:We have shown that the thermal emission of the amorphous dust composed of amorphous silicate dust (a-Si) and amorphous carbon dust (a-C) provides an excellent fit both to the observed intensity and the polarization spectra of molecular clouds. The anomalous microwave emission (AME) originates from the resonance transition of the two-level systems attributed to the a-C with an almost spherical shape. On the other hand, the observed polarized emission in submillimeter wave bands is coming from a-Si. By taking into account a-C, the model prediction of the polarization fraction of the AME is reduced dramatically. Our model prediction of the 3 lower limits of the polarization fraction of the Perseus and W 43 molecular clouds at 17 GHz are 8.129 × 10−5 and 8.012 × 10−6, respectively. The temperature dependence of the heat capacity of a-C shows the peculiar behavior compared with that of a-Si. So far, the properties of a-C are unique to interstellar dust grains. Therefore, we coin our dust model as the cosmic amorphous dust model.
ISSN:2041-8205
2041-8213