Creation of cosmological magnetic fields in a bouncing cosmology

Salim, J. M.; Souza, Naiara Maria de; Bergliaffa, Santiago Esteban Perez; Prokopec, Tomislav

doi:10.1088/1475-7516/2007/04/011

Cited by 30 publications

(25 citation statements)

References 41 publications

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“…Of course, in some sections also torsion can replace the chiral chemical potential itself. Generation of magnetic fields in a bouncing universe without considering torsion has been found by Salim et al [24], but in this paper several different features are considered; here our universe bounce decouples with torsion inside the bubble which is Ricci flat. When we consider the inflating magnetic fields, actually we obtain deflating magnetic fields since the magnetic fields decays with expanding scales as a(t) ≈ t −1 4 , which shows that the magnetic field grows.…”

Section: Conclusion and Discussionmentioning

confidence: 73%

“…When we consider the inflating magnetic fields, actually we obtain deflating magnetic fields since the magnetic fields decays with expanding scales as a(t) ≈ t −1 4 , which shows that the magnetic field grows. However, note that when one uses the cosmic time of EWPT this contraction of the bouncing universe actually imposes a deflation in inflating magnetic fields [24], which is really not possible here due to chiral magnetic effects at the EWPT bouncing phase of the universe. In the latest eras of the universe, Barrow et al [25] have shown that a galactic dynamo can seed the amplification of the magnetic fields obtained from superadiabatic (non-adiabatic) amplification using the GR dynamo equations where non-conventional quantum theory or extradimensional theory is needed.…”

Section: Conclusion and Discussionmentioning

confidence: 93%

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Metric-torsion decay of non-adiabatic chiral helical magnetic fields against chiral dynamo action in bouncing cosmological models

Andrade

2018

Eur. Phys. J. C

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Metric-torsion effects on chiral massless fermions are investigated in the realm of the adiabatic amplification of cosmological magnetic fields (CMFs) in a general relativistic framework and in the framework of Einstein-Cartan (EC) bouncing cosmologies. In GR the chiral effect is proportional to the Hubble factor and the solution of the dynamo equation leads to an adiabatic magnetic field, while in Einstein-Cartan bouncing cosmology we have non-adiabatic magnetic fields where the breaking of adiabaticity is given by a torsion term. Using a EWPT magnetic field of the order of B seed ∼ 10 24 G at 5 pc scale, we obtain a CMF in EC of the order of 10 −10 G, which is still able to seed a galactic dynamo which amplifies this field up to galactic magnetic fields of four orders of magnitude, which is a mild dynamo. In the case of massive chiral fermions it is shown that torsion actually attenuated the convective dynamo term in the dynamo equation obtained from the QED of an electron-positron pair e − e + . Chiral effects on general relativity may lead to strong magnetic fields of the order of ∼ 10 18 G at the early universe resulting from pure metric effects. Strong magnetic fields of the order of B metric−torsion ∼ 10 8 G may be obtained from very strong seed fields. At 1 Mpc scale of the present universe a galactic dynamo seed of the order of 10 −19 G is found. It is shown in this paper that chiral dynamo effects in the expanded universe can be obtained if one takes into account the speed of the cosmic plasma.

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Section: Conclusion and Discussionmentioning

confidence: 73%

Section: Conclusion and Discussionmentioning

confidence: 93%

Metric-torsion decay of non-adiabatic chiral helical magnetic fields against chiral dynamo action in bouncing cosmological models

Andrade

2018

Eur. Phys. J. C

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“…where, we have taken n = 1 such as in (Turner and Widrow, 1988;Salim et al, 2007). From this effective Lagrangean we obtain the field equations for the Friedmann spatially flat metric Equation 8 and 9:…”

Section: Flat Semi-minimal Torsion-photon Coupling Of Rf 2 Lagrangeanmentioning

confidence: 99%

Decoupling Between Torsion and Magnetic Fields in Bouncing Cosmology and Galactic Dynamo Seeds

Andrade¹

2014

Physics International

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Recently Salim et al. (2007), have shown that galactic dynamo seeds can be possibly attainable in bouncing cosmological models with QED Lagrangeans. In this study we generalise their result by include torsion of spacetime in bouncing cosmology. It is shown that by considering a semi-minimal photon-torsion coupling and a Lagrangean of the type RF 2 it is possible to find a fast decoupling between magnetic and torsion fields in the contracting phases of the universe. Besides torsion field decays as 2 3 K a while the magnetic field grows as B∼a −5.5 thus explaining the fast decoupling between the two fields. It is expected that at some point of the contracting phase the amplification of the magnetic field may give rise to a enough strong magnetic field to seed a galactic dynamo.

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“…These models allow well motivated, Minkowski-like initial conditions to be imposed on the perturbations at early times during the contracting phase. The generation of magnetic fields in such scenarios have been explored only to a limited extent [70][71][72].…”

Section: Introductionmentioning

confidence: 99%

Duality and scale invariant magnetic fields from bouncing universes

2016

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Recently, we had numerically shown that, for a non-minimal coupling that is a simple power of the scale factor, scale invariant magnetic fields arise in a class of bouncing universes. In this work, we {\it analytically} evaluate the spectrum of magnetic and electric fields generated in a sub-class of such models. We illustrate that, for cosmological scales which have wavenumbers much smaller than the wavenumber associated with the bounce, the shape of the spectrum is preserved across the bounce. Using the analytic solutions obtained, we also illustrate that the problem of backreaction is severe at the bounce. Finally, we show that the power spectrum of the magnetic field remains invariant under a two parameter family of transformations of the non-minimal coupling function.Comment: v1: 17 pages, 5 figures; v2: 14 pages, 5 figures, bouncing model details and discussion extended, references added, to appear in Phys. Rev.

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Creation of cosmological magnetic fields in a bouncing cosmology

Cited by 30 publications

References 41 publications

Metric-torsion decay of non-adiabatic chiral helical magnetic fields against chiral dynamo action in bouncing cosmological models

Metric-torsion decay of non-adiabatic chiral helical magnetic fields against chiral dynamo action in bouncing cosmological models

Decoupling Between Torsion and Magnetic Fields in Bouncing Cosmology and Galactic Dynamo Seeds

Duality and scale invariant magnetic fields from bouncing universes

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