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(2) n© * -TUVWXTYZ)?/*,[   \(3)  . f ]^_++`=?, a b1( ,1o'  !£ª«/?op+ ¦/+ IJ#-<7.A¬)?p/, H 7->[ cd ./ A/ 7e   !IJ %f% )* 0  YZA( 7g12 ?
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±2006 K 4 ² 12 q³£+´y>  

7. 

Cosmological Magnetic Field: A Fossil of Densityzu++`=?cd!?:*(

Perturbations in the Early Universe

1( {/|*}@~G+< \Keitaro Takahashi, Kiyotomo Ichiki and Naoshi Sugiyama

+,/*< !"#cd :abstract:?? .[ , -&q  )?(Aand how cosmological magnetic ﬁelds are generated. We show thatA+B/ /(/ C$,~G?1r
r D  !"#cd:*i .
Eo/* -* > - %&|()* rr A 37-> + cd
./ A{/7  /(/ + .

It is one of the greatest problems in cosmology whendensity perturbations in the early universe generate magnetic ﬁeld
by considering an e#ect which is so tiny that it has been neglected
so far. By following the evolution of perturbations numerically wegive the spectrum of generated magnetic ﬁeld and show thepossibility that they act as seed ﬁelds for galactic magnetic ﬁelds.

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