Daily Image
29-06-2007
Radio polarimetry in 2.5D
| Submitter: | Drs Brentjens |
| Description: | As part of Michiel Brentjens' PhD thesis, which he defends today at 13:15 in Groningen, Michiel Brentjens and Ger de Bruyn developed an observing technique called "RM-synthesis", which enables extremely sensitive observations of polarized radio emission at low frequencies. By using RM-synthesis, one can separate structures at different so-called "Faraday depths" along the line of sight. If the magnetic field points roughly in the same direction in the field of view, "Faraday depth" enables a crude estimate of which sources are closer than others. The picture shows a wide field WSRT observation of the Perseus cluster at 92 cm wavelength. The source 3C84, or Perseus A, is located at the centre of the cluster. The colours (red, green, blue, and purple) show diffuse polarized emission at increasing Faraday depths. At first it was thought that the purple "doughnut", blue "front", and a big lenticular structure that appeared to be embedded in the "front" were associated to the Perseus cluster. In December 2006 it finally became apparent that the "front" and, probably, the "doughnut" belong to the Milky Way. The nature of these objects is still a mystery. |
| Copyright: | (c) Dr Brentjens 2007 |
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