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news [2017/06/06 13:45]
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news [2017/06/06 13:46] (current)
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 **New observations probe Galactic magnetic fields in the Early Universe**{{proto.jpg?​200 |}} **New observations probe Galactic magnetic fields in the Early Universe**{{proto.jpg?​200 |}}
  
-Nijmegen-based researchers Jamie Farnes and Marijke Haverkorn, together with an international group of astronomers from the U.S., Canada, Mexico, and New Zealand, have tested how magnetic fields form and evolve in early galaxies. Dynamo theory is the primary model describing how magnetic fields develop in galaxies. In this picture, magnetic fields start out as weak seed fields that are small and unordered. These fields then become ordered and amplified by large-scale rotation and turbulence in galaxy disks and halos, eventually leading to the magnetic fields we observe in galaxies today. To test this model, we need observations of the magnetic fields in young protogalaxies. Unfortunately,​ we don’t have the sensitivity to be able to measure these fields directly — but a team of scientists led from Radboud University in the Netherlands have come up with a creative ​alternative. The key is to find early protogalaxies that absorb the light of more distant background objects. If a protogalaxy lies between us and a distant quasar, then magnetic fields of the protogalaxy ​— if present ​— will affect ​the polarization measurements ​of the background quasar. Using this technique, the researchers found a magnetic field 1 million times weaker than that of the Earth and 10 billion light years away. This new study indicates that magnetic fields are indeed being gradually built up in early galaxies by dynamos. This provides the first observational picture of magnetic field evolution in galaxies, lending excellent support to theoretical models.+Nijmegen-based researchers Jamie Farnes and Marijke Haverkorn, together with an international group of astronomers from the U.S., Canada, Mexico, and New Zealand, have tested how magnetic fields form and evolve in early galaxies. Dynamo theory is the primary model describing how magnetic fields develop in galaxies. In this picture, magnetic fields start out as weak seed fields that are small and unordered. These fields then become ordered and amplified by large-scale rotation and turbulence in galaxy disks and halos, eventually leading to the magnetic fields we observe in galaxies today. To test this model, we need observations of the magnetic fields in young protogalaxies. Unfortunately,​ we don’t have the sensitivity to be able to measure these fields directly — but a team of scientists led from Radboud University in the Netherlands have come up with an alternative. The key is to find early protogalaxies that absorb the light of more distant background objects. If a protogalaxy lies between us and a distant quasar, then magnetic fields of the protogalaxy ​if present ​will affect polarization measurements ​from the background quasar. Using this technique, the researchers found a magnetic field 1 million times weaker than that of the Earth and 10 billion light years away. This new study indicates that magnetic fields are indeed being gradually built up in early galaxies by dynamos. This provides the first observational picture of magnetic field evolution in galaxies, lending excellent support to theoretical models.
  
 Read the research highlight from the American Astronomical Society [[http://​aasnova.org/​2017/​06/​02/​probing-magnetic-fields-of-early-galaxies/​|here]] Read the research highlight from the American Astronomical Society [[http://​aasnova.org/​2017/​06/​02/​probing-magnetic-fields-of-early-galaxies/​|here]]