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Large-scale magnetic fields are observed today to be coherent on galactic scales. While there exists an explanation for their amplification and their specific configuration in spiral galaxies -- the dynamo mechanism -- a satisfying…
The galactic magnetic field is commonly supposed to be due to a dynamo acting on some large scale seed field. A major difficulty with this idea is that estimates of reasonable seed field strengths tend to be quite low, on the order of…
The origin and maintenance of coherent magnetic fields in the Universe is reviewed with an emphasis on the possible challenges that arise in their theoretical understanding. We begin with the interesting possibility that magnetic fields…
Cosmic strings are stable topological defects that may have been created at a phase transition in the early universe. It is a growing belief that, for a wide range of theoretical models, such strings may be superconducting and carry…
A framework is introduced for coupling the evolution of galactic magnetic fields sustained by the mean-field dynamo with the formation and evolution of galaxies in cold dark matter cosmology. Estimates of the steady-state strength of the…
Magnetic fields in galaxies and galaxy clusters are amplified from a very weak seed value to the observed $\mu{\rm G}$ strengths by the turbulent dynamo. The seed magnetic field can be of primordial or astrophysical origin. The strength and…
We show that the relatively strong magnetic fields ($\ge 1 \mu$G) in high redshift objects can be explained by the combined action of an evolving protogalactic fluctuation and electrodynamic processes providing the magnetic seed fields.…
Sufficiently large seeds for generating the observed (inter)galactic magnetic fields emerge naturally in string cosmology from the amplification of electromagnetic vacuum fluctuations due to a dynamical dilaton background. The success of…
The origin of intergalactic magnetic fields is still a mystery and several scenarios have been proposed so far: among them, primordial phase transitions, structure formation shocks and galactic outflows. In this work we investigate how…
We present a model for the seeding and evolution of magnetic fields in galaxies by supernovae (SN). SN explosions during galaxy assembly provide seed fields, which are subsequently amplified by compression, shear flows and random motions.…
We point out that the lower bound on the primordial magnetic field required to seed the galactic dynamo is significantly relaxed in an open universe or in a universe with a positive cosmological constant. It is shown that, for reasonable…
We study the cosmic evolution of the magnetic fields of a large sample of spiral galaxies in a cosmologically representative volume by employing a semi-analytic galaxy formation model and numerical dynamo solver in tandem. We start by…
Earlier Enqvist and Olesen have shown that formation of ferromagnetic planar walls in vacuum at GUT scales in comoving plasmas may generate a large scale magnetic field of $B_{now}\simeq{10^{-14}G}$. In this paper we show that starting from…
The observed galactic magnetic fields may have a primordial origin. I briefly review the observations, their interpretation in terms of the dynamo theory, and the current limits on cosmological magnetic fields. Several possible mechanisms…
In this work, we show that ultralight dark photons, which couple to the Standard Model photon through kinetic mixing, can potentially source galactic scale magnetic fields. Although these magnetic fields would be too weak to detect at…
We propose a new mechanism for the generation of primordial magnetic fields, making use of the magnetic fields which are induced by anomalous global strings which couple to electromagnetism via Wess-Zumino type interactions. This mechanism…
This paper examines the generation of seed magnetic fields due to the growth of cosmological perturbations. In the radiation era, different rates of scattering from photons induce local differences in the ion and electron density and…
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…
We performed cosmological, magneto-hydrodynamical simulations to follow the evolution of magnetic fields in galaxy clusters, exploring the possibility that the origin of the magnetic seed fields are galactic outflows during the star-burst…
Building on earlier work, we develop an equation-of-motion method for calculating magnetic seed fields generated from currents arising from charged W fields in bubble collisions during a first-order primordial electroweak phase transition…