Max Planck Institute for Radio Astronomy | 2017 Mar 22
The 100-m radio telescope Effelsberg observes magnetic structures with several million light years extent
[img3="The relic at the outskirts of the galaxy cluster CIZA J2242+53, named „Sausage“ because of its shape, is located at a distance of about two billion light years from us. The contour lines show the intensity of the radio emission at a wavelength of 3 cm, observed with the 100-m Effelsberg radio telescope. The colors represent the distribution of linearly polarized radio intensity at the chosen wavelength, in units of Milli-Jansky per telescope beam. The short dashes indicate the orientation of the magnetic field. The bright source at the bottom is a radio galaxy that belongs to the same galaxy cluster. (© M. Kierdorf et al., A&A 600, A18, 2017)"]http://www.mpifr-bonn.mpg.de/3683279/st ... 030121.jpg[/img3][hr][/hr]Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far. ...
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the diameter of the Milky Way, they host a large number of such stellar systems, along with hot gas, magnetic fields, charged particles, embedded in large haloes of dark matter, the composition of which is unknown. Collision of galaxy clusters leads to a shock compression of the hot cluster gas and of the magnetic fields. The resulting arc-like features are called “relics” and stand out by their radio and X-ray emission. Since their discovery in 1970 with a radio telescope near Cambridge/UK, relics were found in about 70 galaxy clusters so far, but many more are likely to exist. They are messengers of huge gas flows that continuously shape the structure of the universe.
Radio waves are excellent tracers of relics. The compression of magnetic fields orders the field lines, which also affects the emitted radio waves. More precisely, the emission becomes linearly polarized. ...
Relics in Galaxy Clusters at High Radio Frequencies - Maja Kierdorf et al
- Astronomy & Astrophysics 600:A18 (Apr 2017) DOI: 10.1051/0004-6361/201629570
arXiv.org > astro-ph > arXiv:1612.01764 > 06 Dec 2016 (v1), 23 Dec 2016 (v2)