Astron. Astrophys. Suppl. Ser. 138, 31-45

A 1.4 GHz radio continuum and polarization survey at medium Galactic latitudes

II. First section

B. Uyaniker - E. Fürst - W. Reich - P. Reich - R. Wielebinski

Send offprint request: W. Reich

Max-Planck-Institut für Radioastronomie, Postfach 2024, 53010 Bonn, Germany

Received September 30, 1998; accepted April 8, 1999

Abstract:

We present the first section of a radio continuum and polarization survey at medium Galactic latitudes carried out with the Effelsberg 100-m telescope at 1.4 GHz. Four large fields have been observed, which all together cover an area of about $1100~\ifmmode\hbox{\rlap{$\sqcap$}$\sqcup$}\else{\unskip\nobreak\hfil \penalty5... ...box{\rlap{$\sqcap$}$\sqcup$} \parfillskip=0pt\finalhyphendemerits=0\endgraf}\fi$. The rms-sensitivity is about 15 mK T_B (about 7 mJy/beam area) in total intensity and is limited by confusion. A sensitivity of 8 mK T_B is obtained in linear polarization. The angular resolution of the observations is 9$.\mkern-4mu^\prime$35. The maps in total intensity and linear polarization have been absolutely calibrated by low resolution data where available. Significant linear polarization is seen in all the maps. In general, the intensity fluctuations measured in linear polarization are not correlated with total intensity structures. Areas of high polarization of some degrees extent are seen, again with no apparent corresponding total intensity feature. Modulation of polarized background emission by spatially varying Faraday rotation seems the most likely explanation. Quite unexpected is the detection of filamentary and ring-like depolarization structures in the direction of the anticentre region, whose extents are up to about $3\hbox{$^\circ$}$.

Key words: surveys -- ISM: structure -- radio continuum: ISM polarization -- ISM: magnetic fields