Faculty of Mathematics and Natural Sciences
University of Leiden
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2333 CA Leiden
The Netherlands
www.strw.leidenuniv.nl
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The intensity of polarization at the frequency 349 MHz, in a field of about 8 by 10 degrees around (l,b) = (165, 16) as a probe for small scale structure of the warm interstellar medium in the Milky Way disk.





Since significant polarization of the diffuse radio continuum background of our Galaxy was discovered by Wieringa et al. some ten years ago, this has proved to be an important way to probe the small scale structure of the warm interstellar medium in the Milky Way disk.

Marijke Haverkorn, Peter Katgert and Ger de Bruijn (ASTRON) observed multi-frequency maps of the galactic synchrotron continuum with the Westerbork Synthesis Radio Telescope in the Netherlands. The map shows polarized intensity at one frequency (349 MHz) in a field of about 8 by 10 degrees around (l,b) = (165, 16). The brightness temperature of the polarized structures goes up to 10 K, where noise is about 0.5 K. A variety of topology in polarized structure can be seen in this and other fields. The black, narrow, wriggly structures are depolarized 'canals' of one synthesized beam wide and are not physical structures but caused by beam depolarization. The inset below shows a representative phi(lambda2) -plot.



The multi-frequency maps yield Rotation Measures of the magneto-ionized medium in the disk of the Galaxy, that give information on the turbulent structure of electron density and of magnetic field parallel to the line of sight, along many contiguous lines of sight.




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