Dark matter and generation of galactic magnetic fields 
			 Zurab Berezhiani
				Università degli Studi de l'Aquila and LNGS, Italy
			
			Mercredi 16/10/2013, 14:15
			Salle Claude Itzykson, Bât. 774, Orme des Merisiers
			A  new scenario for creation of galactic  magnetic fields is proposed which is operative at the cosmological epoch of the galaxy formation, and which relies on unconventional properties of dark matter. Namely, it requires existence of feeble but long range interaction between the dark matter particles and electrons. In particular, millicharged dark matter particles  or mirror particles with the photon kinetic mixing to the usual photon can be considered. We show that in rotating protogalaxies circular electric currents  can be generated by the interactions of free electrons with dark matter particles in the halo, while the impact of such
interactions on galactic protons is considerably weaker. The induced currents may be strong enough to create the observed magnetic fields on the galaxy scales  with the help of moderate dynamo amplification. In addition, 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. The global motion of the ionized gas could produce sufficiently large magnetic fields also in filaments and galaxy clusters.