Cosmic Amorphous Dust Model as the Origin of Anomalous Microwave Emission

Masashi Nashimoto, Makoto Hattori, Frédérick Poidevin, Ricardo Génova-Santos

Research output: Contribution to journalArticlepeer-review

Abstract

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 3σ 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.

Original languageEnglish
Article numberL40
JournalAstrophysical Journal Letters
Volume900
Issue number2
DOIs
Publication statusPublished - 2020 Sep 10

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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