Simulation 2
The movie shows the time evolution of a galaxy cluster, which grows continuously as time progresses. Large lumps of matter occasionally fall into the cluster. Such an event is called merger. In the early state, the magnetic field is not strong enough to measurably rotate the polarisation of background sources. As time progresses, the cluster material is compressed. The magnetic field is amplified, and the Faraday-rotation pattern coded in red and blue appears. When a merger event happens, the Faraday-rotation pattern changes strongly, illustrating the considerable impact of mergers on the magnetic field.

Maps are projected against the sides of the cube displayed, showing what observers would see from the respective directions. The grey surface encloses the part of the cluster in which the plasma density exceeds a certain value. The pink arrows illustrate the magnetic field in a cross section through the cluster. The grey lines on the projected maps are density contours. The coloured regions indicate what Faraday rotation could be measured if a radio source was located at that position behind the cluster. Red and blue colours distinguish the sense of the rotation; the amount of the rotation is indicated by the brightness of the colour.

Press the Reload Button to restart the movie.