Magnetic field in early universe

[shadishacker]

Dear all,
Can anyone give me a time scale/ redshift range as an estimate for the formation of magnetic fields in the universe?

 

[wolram]

Dear all,
Can anyone give me a time scale/ redshift range as an estimate for the formation of magnetic fields in the universe?

Hope this helps shadishacker.
http://arxiv.org/abs/astro-ph/0009061

This review concerns the origin and the possible effects of magnetic fields in the early Universe. We start by providing to the reader with a short overview of the current state of art of observations of cosmic magnetic fields. We then illustrate the arguments in favour of a primordial origin of magnetic fields in the galaxies and in the clusters of galaxies. We argue that the most promising way to test this hypothesis is to look for possible imprints of magnetic fields on the temperature and polarization anisotropies of the cosmic microwave background radiation (CMBR). With this purpose in mind, we provide a review of the most relevant effects of magnetic fields on the CMBR. A long chapter of this review is dedicated to particle physics inspired models which predict the generation of magnetic fields during the early Universe evolution. Although it is still unclear if any of these models can really explain the origin of galactic and intergalactic magnetic fields, we show that interesting effects may arise anyhow. Among these effects, we discuss the consequences of strong magnetic fields on the big-bang nucleosynthesis, on the masses and couplings of the matter constituents, on the electroweak phase transition, and on the baryon and lepton number violating sphaleron processes. Several intriguing common aspects, and possible interplay, of magnetogenesis and baryogenesis are also dicussed.

 

[shadishacker]

Hope this helps shadishacker.
http://arxiv.org/abs/astro-ph/0009061

This review concerns the origin and the possible effects of magnetic fields in the early Universe. We start by providing to the reader with a short overview of the current state of art of observations of cosmic magnetic fields. We then illustrate the arguments in favour of a primordial origin of magnetic fields in the galaxies and in the clusters of galaxies. We argue that the most promising way to test this hypothesis is to look for possible imprints of magnetic fields on the temperature and polarization anisotropies of the cosmic microwave background radiation (CMBR). With this purpose in mind, we provide a review of the most relevant effects of magnetic fields on the CMBR. A long chapter of this review is dedicated to particle physics inspired models which predict the generation of magnetic fields during the early Universe evolution. Although it is still unclear if any of these models can really explain the origin of galactic and intergalactic magnetic fields, we show that interesting effects may arise anyhow. Among these effects, we discuss the consequences of strong magnetic fields on the big-bang nucleosynthesis, on the masses and couplings of the matter constituents, on the electroweak phase transition, and on the baryon and lepton number violating sphaleron processes. Several intriguing common aspects, and possible interplay, of magnetogenesis and baryogenesis are also dicussed.

Could you please give me a redshift scale?
The paper is rather long, and I just need to have an estimation.
Do the seeds appear before inflation?
After inflation?
Any other specific cosmological era?

 

[Chronos]

The effects of magnetic fields during star formation are fairly trivial, how significant could it be in the early universe?

 

[rootone]

The electromagnetic field is thought to have emerged at a very early time and that fits quite well with inflation cosmology.
Approximately 10−36 seconds after the big bang.
https://en.wikipedia.org/wiki/Electroweak_epoch

 

[cristo]

I guess the answer is that we don't really know. There are various mechanisms for generation of magnetic fields, but there is not one definitive agreed upon solution. Generally, since magnetic fields appear to be correlated on large scales, and appear in voids, it is expected that they are cosmic in origin - that is, they were created in the very early universe, or during inflation. Additionally, magnetic fields can be created from phase transitions in the very early universe.

 

[shadishacker]

I guess the answer is that we don't really know. There are various mechanisms for generation of magnetic fields, but there is not one definitive agreed upon solution. Generally, since magnetic fields appear to be correlated on large scales, and appear in voids, it is expected that they are cosmic in origin - that is, they were created in the very early universe, or during inflation. Additionally, magnetic fields can be created from phase transitions in the very early universe.

Thanks for the great reply.

 

[Hornbein]

since magnetic fields appear to be correlated on large scales, and appear in voids.

How might an astronomer detect a magnetic field in a void?

 

[rootone]

Near Earth space is a void for most practical purposes, and the Earth's magnetic field is present in it.
A directly observable effect of it is the channeling of charged particles in the solar wind which results in arorae near the poles.
I am fairly sure these have been observed also on other planets which have strong magnetic fields.
Also I am sure there must have been several satellites or other spacecraft which for one reason or another have had equipment on board that can detect the presence of magnetic fields in space.

 

[cristo]

How might an astronomer detect a magnetic field in a void?

See, e.g., A. Neronov and I. Vovk, Science 328, 73 (2010) [http://arxiv.org/abs/1006.3504] . Distant photons traveling through the void interact with background light and produce electron/positron pairs. These pairs would travel in the same direction as the initial photon, however in the presence of a magnetic field are deflected, and the emission off this secondary cascade is suppressed. This has been observed in many distant TeV blazars, which is therefore good evidence of the existence of magnetic fields in voids.