We have observed the HII region RCW175 with the 64-m Parkes telescope at 8.4Â GHz and 13.5Â GHz in total intensity , and at 21.5Â GHz in both total intensity and polarization .
High angular resolution ranging from 1Â arcmin to 2.4Â arcmin , high sensitivity , and polarization capability enable us to perform a detailed study of the different constituents of the HII region .
For the first time , we resolve three distinct regions at microwave frequencies , two of which are part of the same annular diffuse structure .
Our observations enable us to confirm the presence of anomalous microwave emission from RCW175 .
Fitting the integrated flux density across the entire region with the currently available spinning dust models , using physically motivated assumptions , indicates the presence of at least two spinning dust components : a warm component ( T _ { gas } = 5800 Â K ) with a relatively large hydrogen number density n _ { H } = 26.3/cm ^ { 3 } and a cold component ( T _ { gas } = 100 Â K ) with a hydrogen number density of n _ { H } = 150/cm ^ { 3 } .
The present study is an example highlighting the potential of using high angular-resolution microwave data to break model parameter degeneracies .
Thanks to the spectral coverage and angular resolution of the Parkes observations , we have been able to derive one of the first anomalous microwave emission/excess maps , at 13.5Â GHz , showing clear evidence that the bulk of the anomalous emission arises in particular from one of the source components , with some additional contribution from the diffuse structure .
A cross-correlation analysis with thermal dust emission has shown a high degree of correlation with one of the regions within RCW175 .
In the center of RCW175 , we find an average polarized emission at 21.5Â GHz of 2.2 \pm 0.2 ( rand . ) \pm 0.3 ( sys . ) % of the total emission , where we have included both systematic and statistical uncertainties at 68 % CL .
This polarized emission could be due to sub-dominant synchrotron emission from the region and is thus consistent with very faint or non-polarized emission associated with anomalous microwave emission .