Anomalous Emission from HII regions

TL;DR

This paper presents evidence of anomalous microwave emission from HII regions, likely caused by spinning dust, with new detections at 31 GHz in RCW175 supporting this hypothesis.

Contribution

It provides new observational evidence of spinning dust emission in HII regions, including a novel detection at 31 GHz in RCW175.

Findings

Detection of excess emission at 31 GHz in RCW175

Tentative evidence of excess emission in other HII regions at ~30 GHz

Spinning dust remains the most plausible explanation for the anomalous emission

Abstract

Spinning dust appears to be the best explanation for the anomalous emission that has been observed at $\sim 10-60$ GHz. One of the best examples of spinning dust comes from a HII region in the Perseus molecular cloud. Observations of other HII regions also show tentative evidence for excess emission at frequencies $\sim 30$ GHz, although at lower emissivity levels. A new detection of excess emission at 31 GHz in the HII region RCW175 has been made. The most plausible explanation again comes from spinning dust. HII regions are a good place to look for spinning dust as long as accurate radio data spanning the $\sim 5-100$ GHz range is available.