Monday, July 29, 2013

1307.6953 (Zurab Berezhiani et al.)

Dark matter and generation of galactic magnetic fields    [PDF]

Zurab Berezhiani, A. D. Dolgov, I. I. Tkachev
A mechanism for creation of galactic and intergalactic magnetic fields at a recent cosmological epoch is proposed. We show that in rotating protogalaxies circular electric currents are generated by the interactions of free electrons with dark matter particles while the impact of such interactions on galactic protons is considerably weaker. Light dark matter particles can be efficient for generation of such currents if these particles have some long range interactions. In particular, millicharged warm dark matter particles or light mirror particles with the photon kinetic mixing to the usual matter are considered. The induced currents may be strong enough to create the observed magnetic fields on the galaxy scales without need for a strong dynamo amplification. On the other hand, the angular momentum transfer from the rotating gas to dark matter component could change the dark matter profile and formation of cusps at galactic centers would be inhibited. We also discuss how the global motion of the ionized gas could produce sufficiently large magnetic fields in filaments and galaxy clusters.
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