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Cosmological Seed Fields versus Seed Fields Generated in Protogalaxies

Galactic Magnetism –Perspectives of Observation and Modeling May 16 - 20 , 201 1 Pushchino, Moscow region, Russia. Cosmological Seed Fields versus Seed Fields Generated in Protogalaxies. Dmitry Sokoloff Moscow State University Moscow, Russia in collaboration with D.Moss and V.Semikoz.

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Cosmological Seed Fields versus Seed Fields Generated in Protogalaxies

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  1. Galactic Magnetism –Perspectives of Observation and ModelingMay 16 - 20, 2011Pushchino, Moscow region, Russia Cosmological Seed Fields versus Seed Fields Generated in Protogalaxies Dmitry Sokoloff Moscow State University Moscow, Russia in collaboration with D.Moss and V.Semikoz

  2. GALACTIC DYNAMO Ω BT Br Basic mechanism Differential rotation α Br BT Helicity • The excitation mechanism requires a seed magnetic field. • Two options: • Magnetic field is created in after recombination • A cosmological seed field • How to decide which option is better?

  3. A standard approach: formulate scenarios for both cases, isolate specific features and try to confront them with observations A scenario for magnetic fields created after recombination: talks of Moss, Arshakian, …

  4. Seeds in protogalaxies + conventional mean-field dynamo

  5. Spatial configurations

  6. Cosmological seeds (a standard viewpoint) • Homogeneous magnetic field. • Do not destroy isotropy provided is weak enough (< 1011G is more then sufficient). • Still can be strong enough to be a seed

  7. Homogeneous relic field+ dynamo: it works unexpectedly bad (simulations of D.Moss)

  8. Rotation expels homogeneous field on the remote part of the galaxy(simulations of D.Moss)

  9. A cosmological magnetic field is useful to explain the baryon asymmetrySemikoz, Sokoloff, Valle,PRD 2009

  10. We can not distinguish between • Small-scale cosmological seed + dynamo • A battery mechanism + small scale dynamo + mean-field dynamo • A large-scale seed + small-scale dynamo + Mean-field dynamo

  11. What says cosmology? • 1. Everything is known (this statement persists) • Nothing about homogeneous magnetic field • This idea looked strange 10 years ago • It looks attractive today • My interpretation: the topic is completely obscure

  12. A possibility to go further • Neronov and D.Semikoz: • Magnetic fields between galactic clusters • (10-15 G) • Faraday rotation? • Small-scale or large-scale fields?

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