Vertical motions in the disk of NGC 5668 as seen with optical Fabry-Perot spectroscopy

We have observed the nearly face-on spiral galaxy NGC 5668 with the TAURUS II Fabry-Perot interferometer at the William Herschel Telescope using the $H\alpha$ line to study the kinematics of the ionized gas. From the extracted data cube we construct intensity, velocity and velocity dispersion maps. We calculate the rotation curve in the innermost 2 arcmin and we use the residual velocity field to look for regions with important vertical motions. By comparing the geometry of these regions in the residual velocity field with the geometry in the intensity and velocity dispersion maps we are able to select some regions which are very likely to be shells or chimneys in the disk. The geometry and size of these regions are very similar to the shells or chimneys detected in other galaxies by different means. Moreover, it is worth noting than this galaxy has been reported to have a population of neutral hydrogen high velocity clouds (Schulman et al. 1996) which, according to these observations, could have been originated by chimneys similar to those reported in this paper.Comment: 7 pages with 9 figures. LaTeX file using A&A v4.0 macro

Large-Scale Magnetic Fields, Dark Energy and QCD

Cosmological magnetic fields are being observed with ever increasing correlation lengths, possibly reaching the size of superclusters, therefore disfavouring the conventional picture of generation through primordial seeds later amplified by galaxy-bound dynamo mechanisms. In this paper we put forward a fundamentally different approach that links such large-scale magnetic fields to the cosmological vacuum energy. In our scenario the dark energy is due to the Veneziano ghost (which solves the $U(1)_A$ problem in QCD). The Veneziano ghost couples through the triangle anomaly to the electromagnetic field with a constant which is unambiguously fixed in the standard model. While this interaction does not produce any physical effects in Minkowski space, it triggers the generation of a magnetic field in an expanding universe at every epoch. The induced energy of the magnetic field is thus proportional to cosmological vacuum energy: $\rho_{EM}\simeq B^2 \simeq (\frac{\alpha}{4\pi})^2 \rho_{DE}$, $\rho_{DE}$ hence acting as a source for the magnetic energy $\rho_{EM}$. The corresponding numerical estimate leads to a magnitude in the nG range. There are two unique and distinctive predictions of our proposal: an uninterrupted active generation of Hubble size correlated magnetic fields throughout the evolution of the universe; the presence of parity violation on the enormous scales $1/H$, which apparently has been already observed in CMB. These predictions are entirely rooted into the standard model of particle physics.Comment: jhep style, 22 pages, v2 with updated estimates and extended discussion on parity violation, v3 as published (references updated

Galaxy rotation curves: the effect of j x B force

Using the Galaxy as an example, we study the effect of j x B force on the rotational curves of gas and plasma in galaxies. Acceptable model for the galactic magnetic field and plausible physical parameters are used to fit the flat rotational curve for gas and plasma based on the observed baryonic (visible) matter distribution and j x B force term in the static MHD equation of motion. We also study the effects of varied strength of the magnetic field, its pitch angle and length scale on the rotational curves. We show that j x B force does not play an important role on the plasma dynamics in the intermediate range of distances 6-12 kpc from the centre, whilst the effect is sizable for larger r (r > 15 kpc), where it is the most crucial.Comment: Accepted for publication in Astrophysics & Space Science (final printed version, typos in proofs corrected