Evolution of the large-scale tail of primordial magnetic fields

AbstractThe origin of large-scale magnetic fields is an unsolved problem in cosmology. In order to overcome, a possible scenario comes from the idea that these fields emerged from a small primordial magnetic field (PMF), produced in the early universe. This field could lead to the observed large-scales magnetic fields but also, would have left an imprint on the cosmic microwave background (CMB). In this work we summarize some statistical properties of this PMFs on the FLRW background. Then, we show the resulting PMF power spectrum using cosmological perturbation theory and some effects of PMFs on the CMB anisotropies.

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Large-scale primordial magnetic fields from inflation and preheating

10.1063/1.1363559 ◽

2001 ◽

Cited By ~ 5

Author(s):

Ola Törnkvist

Keyword(s):

Magnetic Fields ◽

Large Scale ◽

Primordial Magnetic Fields

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Tracing Primordial Magnetic Fields with 21 cm Line Observations

Galaxies ◽

10.3390/galaxies7010037 ◽

2019 ◽

Vol 7 (1) ◽

pp. 37 ◽

Cited By ~ 1

Author(s):

Kerstin Kunze

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Cosmic Microwave Background ◽

Large Scale ◽

Numerical Solutions ◽

Gaussian Random Field ◽

Microwave Background ◽

Matter Power Spectrum ◽

Primordial Magnetic Fields ◽

The Universe

Magnetic fields are observed on a large range of scales in the universe. Up until recently, the evidence always pointed to magnetic fields associated with some kind of structure, from planets to clusters of galaxies. Blazar observations have been used to posit the first evidence of truly cosmological magnetic fields or void magnetic fields. A cosmological magnetic field generated in the very early universe before recombination has implications for the cosmic microwave background (CMB), large scale structure as well as the 21 cm line signal. In particular, the Lorentz term causes a change in the linear matter power spectrum. Its implication on the 21 cm line signal was the focus of our recent simulations which will be summarised here. Modelling the cosmological magnetic field as a gaussian random field numerical solutions were found for magnetic fields with present day amplitudes of 5 nG and negative spectral indices which are within the range of observational constraints imposed by the cosmic microwave background (CMB).

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CONSTRAINING PRIMORDIAL MAGNETIC FIELDS THROUGH LARGE-SCALE STRUCTURE

The Astrophysical Journal ◽

10.1088/0004-637x/770/1/47 ◽

2013 ◽

Vol 770 (1) ◽

pp. 47 ◽

Cited By ~ 30

Author(s):

Tina Kahniashvili ◽

Yurii Maravin ◽

Aravind Natarajan ◽

Nicholas Battaglia ◽

Alexander G. Tevzadze

Keyword(s):

Magnetic Fields ◽

Large Scale ◽

Large Scale Structure ◽

Scale Structure ◽

Primordial Magnetic Fields

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PRIMORDIAL MAGNETIC FIELDS

International Journal of Modern Physics D ◽

10.1142/s0218271898000243 ◽

1998 ◽

Vol 07 (03) ◽

pp. 331-349 ◽

Cited By ~ 82

Author(s):

KARI ENQVIST

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Particle Physics ◽

Large Scale ◽

Magnetic Energy ◽

Galactic Magnetic Fields ◽

Microscopic Field ◽

Primordial Magnetic Fields ◽

Primordial Magnetic Field ◽

The Magnetic Field

The explanation of the observed galactic magnetic fields may require the existence of a primordial magnetic field. Such a field may arise during the early cosmological phase transitions, or because of other particle physics related phenomena in the very early universe reviewed here. The turbulent evolution of the initial, randomly fluctuating microscopic field to a large-scale macroscopic field can be described in terms of a shell model, which provides an approximation to the complete magnetohydrodynamics. The results indicate that there is an inverse cascade of magnetic energy whereby the coherence of the magnetic field is increased by many orders of magnitude. Cosmological seed fields roughly of the order of 10-20 G at the scale of protogalaxy, as required by the dynamo explanation of galactic magnetic fields, thus seem plausible.

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An 84-μG Magnetic Field in a Galaxy at Z=0.692?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308027439 ◽

2008 ◽

Vol 4 (S254) ◽

pp. 95-96

Author(s):

Arthur M. Wolfe ◽

Regina A. Jorgenson ◽

Timothy Robishaw ◽

Carl Heiles ◽

Jason X. Prochaska

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Faraday Rotation ◽

Large Scale ◽

Dynamo Model ◽

Magnetic Field Generation ◽

Interstellar Gas ◽

Splitting Technique ◽

Average Value ◽

The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

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