Related papers: On a Theory for Nonminimal Gravitational-Electroma…
The existence of magnetic fields in the universe is unmistakable. They are observed at all scales from stars to galaxy clusters. However, the origin of these fields remains enigmatic. It is believed that magnetic field seeds may have…
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…
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…
Basically the only existing theories for the creation of a magnetic field B in the Universe are the creation of a seed field of order 10^{-20} G in spiral galaxy which is subsequently supposedly amplified up to the observed 10^{-6} -…
Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We critically review the current status of the galactic…
We study the effect of variations of the electromagnetic coupling on the process of generation of primordial magnetic fields. We find that only through a significant growth of the electromagnetic coupling minimum seed fields can be…
The generation of primordial magnetic seed fields during inflation is studied in a theory derived from the one-loop vacuum polarization effective action of the photon in a curved background. This includes terms which couple the curvature to…
A primordial magnetic field may be generated during an inflationary period if conformal invariance is broken. We reexamine and generalize previous results about the magnetic field produced by couplings of the form $R^n…
A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters. These fields are characterized by a modest strength (10^{-7}-10^{-5} G) and huge spatial scale (~Mpc). It is generally assumed that…
Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic…
Magnetic fields are present on all scales in the Universe. While we understand the processes which amplify the fields fairly well, we do not have a "natural" mechanism to generate the small initial seed fields. By using fully relativistic…
Primordial magnetic fields could explain the large-scale magnetic fields present in the Universe. Inflation and phase transitions in the early Universe could give rise to such fields with unique characteristics. We investigate the…
In this work we consider the most general electromagnetic theory in curved space-time leading to linear second order differential equations, including non-minimal couplings to the space-time curvature. We assume the presence of a temporal…
A possible explanation for the origin of the magnetic fields observed today in matter structures is that they were generated in the primordial universe. After briefly revising the model of a primordial stochastic magnetic field and…
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…
Inflation has the potential to seed the galactic magnetic fields observed today. However, there is an obstacle to the amplification of the quantum fluctuations of the electromagnetic field during inflation: namely the conformal invariance…
After a discussion of the inflationary production of primordial magnetic seeds, and a short review of various possible mechanisms, we concentrate on the analysis of the photon-dilaton coupling typical of string theory models. Particular…
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…
We review the possible mechanisms for the generation of cosmological magnetic fields, discuss their evolution in an expanding Universe filled with the cosmic plasma and provide a critical review of the literature on the subject. We put…
We study the generation of primordial magnetic fields, coherent over cosmologically interesting scales, by gravitational creation of charged scalar particles during the reheating period. We show that magnetic fields consistent with those…