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(Referência obtida automaticamente do SciELO, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Small scale magnetic field evolution in the first objects formed in the universe

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Autor(es):
Alejandra Kandus ; Reuven Opher ; Saulo M. R. Barros
Número total de Autores: 3
Tipo de documento: Artigo Científico
Fonte: Brazilian Journal of Physics; v. 34, n. 4b, p. 1651-1654, Dez. 2004.
Resumo

Large scale magnetic fields in galaxies are thought to be generated, by a mean field dynamo. In order to have generated the fields observed, the dynamo would have had to have operated for a sufficiently long period of time. However, magnetic fields of similar intensities to the one in our galaxy, are observed in high redshift galaxies, where a mean field dynamo would not have had time to produce the observed fields. MHD turbulence produces small scale magnetic fields at a faster rate than it does mean fields, which can diffuse toward larger scales. If the turbulence is helical, magnetic fields generated at small scales can become correlated over large scales. We study the evolution of magnetic field correlations in the first objects formed in the universe, due to the action of a turbulent, helical, stochastic dynamo, for redshifts 5 < z < 10. Ambipolar diffusion can play a significant role in this process due to the low level of ionization of the gas in the first objects. We show that for reasonable values of the parameters that characterize the turbulent plasma in the time interval considered, fields can grow to high intensities (~ muG), with large coherence lengths (~ 2 - 6 kpc). (AU)

Processo FAPESP: 00/06770-2 - Radiação cósmica de fundo em microondas e formação de estruturas no universo
Beneficiário:Reuven Opher
Linha de fomento: Auxílio à Pesquisa - Temático