A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype
2013
We present a Stokes I, Q and U survey at 189 MHz with the
Murchison Widefield Array32-element prototype covering 2400
square degrees. The survey has a 15.6 arcmin
angular resolutionand achieves a noise level of 15 mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images and deconvolution of the
point spread functionthrough forward modeling. We present a point source catalogue down to a
flux limitof 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8 \pm 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13 K, primarily with positive rotation measure values smaller than +10 rad/m^2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred
parsecs). There is a large sky area at 2^h30^m where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at $(\alpha,\delta) = (4^h,-27^\circ.6)$ in terms of three dimensional power spectra
Keywords:
-
Correction
-
Source
-
Cite
-
Save
0
References
59
Citations
NaN
KQI