Related papers: Synthesizing Observations and Theory to Understand…
Mean-field galactic dynamo theory is the leading theory to explain the prevalence of regular magnetic fields in spiral galaxies, but its systematic comparison with observations is still incomplete and fragmentary. Here we compare…
Many spiral galaxies host magnetic fields with energy densities comparable to those of the turbulent and thermal motions of their interstellar gas. However, quantitative comparison between magnetic field properties inferred from observation…
Observational evidence for dynamo action in spiral galaxies is reviewed, and the capabilities of various theories in explaining the basic features of galactic magnetic fields are discussed. Mean-field dynamo models appear to be unique in…
Both observations and modelling of magnetic fields in the diffuse interstellar gas of spiral galaxies are well developed but the theory has been confronted with observations for only a handful of individual galaxies. There is now sufficient…
We argue that pitch angles of the azimuthally averaged large-scale or mean magnetic fields in nearby spiral galaxies inferred from observations can tentatively be explained with simple galactic dynamo models. Agreement is not perfect, but…
After a short introduction on how we get information of the magnetic fields from radio observations I discuss the results concerning the magnetic field structure in galaxies: Large-scale regular magnetic field pattern of spiral structure…
We review our current understanding of galactic dynamo theory, paying particular attention to numerical simulations both of the mean-field equations and the original three-dimensional equations relevant to describing the magnetic field…
We seek the conditions for a {\it steady} mean field galactic dynamo. The parameter set is reduced to those appearing in the $\alpha^2$ and $\alpha/\omega$ dynamo, namely velocity amplitudes, and the ratio of sub-scale helicity to…
Context. Observations of polarized radio emission show that large-scale (regular) magnetic fields in spiral galaxies are not axisymmetric, but generally stronger in interarm regions. In some nearby galaxies such as NGC 6946 they are…
A review of galactic magnetic fields is given with emphasis on simple analytical solutions of relevant equations and detailed comparison with observations. It is shown that mean-field dynamo theory, in its simplest form, is in a remarkably…
Context. Regularly-spaced, star-forming regions along the spiral arms of nearby galaxies provide insight into the early stages and initial conditions of star formation. The regular separation of these star-forming regions suggests spiral…
Observations of dwarf galaxies suggest the presence of large-scale magnetic fields. However the size and slow rotation of these galaxies appear insufficient to support a mean-field dynamo action to excite such fields. Here we suggest a new…
(abridged) We investigate the possibility to recognize the magnetic field structures in nearby galaxies and to test the cosmological evolution of their large- and small-scale magnetic fields with the SKA and its precursors. We estimate the…
Spiral galaxies host dynamically important magnetic fields which can affect gas flows in the disks and halos. Total magnetic fields in spiral galaxies are strongest (up to 30 \muG) in the spiral arms where they are mostly turbulent or…
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…
The magnetic fields of spiral galaxies are so strong that they cannot be primordial. Their typical values are over one billion times higher than any value predicted for the early Universe. Explaining this immense growth and incorporating it…
Observations of synchrotron radiation and the Faraday rotation of its polarized component allow us to investigate the magnetic properties of the diffuse interstellar medium in nearby galaxies, on scales down to roughly one hundred parsecs.…
The exploration of mean-field galactic dynamos affected by a galactic spiral pattern, begun in Chamandy et al. (2013, hereafter Paper I) with numerical simulations, is continued here with an asymptotic solution. The mean-field dynamo model…
Radio continuum observations allow to reveal the magnetic field structure in the disk and halo of nearby spiral galaxies, their magnetic field strength and vertical scale heights. The spiral galaxies studied so far show a similar magnetic…
We search for observational signatures of magnetic helicity in data from all-sky radio polarization surveys of the Milky Way Galaxy. Such a detection would help confirm the dynamo origin of the field and may provide new observational…