Abstract
Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ~10–60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and ρ Ophiuchi
molecular clouds. The spectra are well fitted by a combination of
free-free radiation, cosmic microwave background, thermal dust, and
electric dipole radiation from small spinning dust grains. The spinning
dust spectra are the most precisely measured to date, and show the high
frequency side clearly for the first time. The spectra have a peak in
the range 20–40 GHz and are detected at high significances of 17.1σ for Perseus and 8.4σ for ρ Ophiuchi.
In Perseus, spinning dust in the dense molecular gas can account for
most of the AME; the low density atomic gas appears to play a minor
role. In ρ Ophiuchi, the ~30 GHz peak is dominated by dense
molecular gas, but there is an indication of an extended tail at
frequencies 50–100 GHz, which can be accounted for by irradiated low
density atomic gas. The dust parameters are consistent with those
derived from other measurements. We have also searched the Planck map
at 28.5 GHz for candidate AME regions, by subtracting a simple model of
the synchrotron, free-free, and thermal dust. We present spectra for
two of the candidates; S140 and S235 are bright Hii regions that show
evidence for AME, and are well fitted by spinning dust models.
Original language | English |
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Article number | A20 |
Number of pages | 17 |
Journal | Astronomy and Astrophysics |
Volume | 536 |
DOIs | |
Publication status | Published - 2011 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Galaxy: general
- ISM: general
- radiation mechanisms
- general
- radio continuum
- ISM
- submillimeter: ISM