The complex galaxy cluster Abell 514: New results obtained with the XMM - Newton satellite

We study the X-ray morphology and dynamics of the galaxy cluster Abell 514. Also, the relation between the X-ray properties and Faraday Rotation measures of this cluster are investigated in order to study the connection of magnetic fields and the intra-cluster medium. We use two combined XMM - Newton pointings that are split into three distinct observations. The data allow us to evaluate the overall cluster properties like temperature and metallicity with high accuracy. Additionally, a temperature map and the metallicity distribution are computed, which are used to study the dynamical state of the cluster in detail. Abell 514 represents an interesting merger cluster with many substructures visible in the X-ray image and in the temperature and abundance distributions. The new XMM - Newton data of Abell 514 confirm the relation between the X-ray brightness and the sigma of the Rotation Measure (S_X - sigma_RM relation) proposed by Dolag et al. (2001).Comment: 9 pages, 13 figures, accepted for publication in A&

Submillimeter detection of the Sunyaev -- Zel'dovich effect toward the most luminous X-ray cluster at z=0.45

We report on the detection of the Sunyaev -- Zel'dovich (SZ) signals toward the most luminous X-ray cluster RXJ1347-1145 at Nobeyama Radio Observatory (21 and 43 GHz) and at James Clerk Maxwell Telescope (350 GHz). In particular the latter is the first successful detection of the SZ temperature increment in the submillimeter band which resolved the profile of a cluster of galaxies. Both the observed spectral dependence and the radial profile of the SZ signals are fully consistent with those expected from the X-ray observation of the cluster. The combined analysis of 21GHz and 350GHz data reproduces the temperature and core-radius of the cluster determined with the ROSAT and ASCA satellites when we adopt the slope of the density profile from the X-ray observations. Therefore our present data provide the strongest and most convincing case for the detection of the submillimeter SZ signal from the cluster, as well as in the Rayleigh -- Jeans regime. We also discuss briefly the cosmological implications of the present results.Comment: 11 pages, The Astrophysical Journal (Letters), in pres

An abstract version of the concentration compactness principle

We prove an abstract version of concentration compactness principle in Hilbert space and show its applications to a range of elliptic problems on unbounded domains.We prove an abstract version of concentration compactness principle in Hilbert space and show its applications to a range of elliptic problems on unbounded domains

Axial, induced pseudoscalar, and pion-nucleon form factors in manifestly Lorentz-invariant chiral perturbation theory

We calculate the nucleon form factors G_A and G_P of the isovector axial-vector current and the pion-nucleon form factor G_piN in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including order O(p^4). In addition to the standard treatment including the nucleon and pions, we also consider the axial-vector meson a_1 as an explicit degree of freedom. This is achieved by using the reformulated infrared renormalization scheme. We find that the inclusion of the axial-vector meson effectively results in one additional low-energy coupling constant that we determine by a fit to the data for G_A. The inclusion of the axial-vector meson results in an improved description of the experimental data for G_A, while the contribution to G_P is small.Comment: 21 pages, 9 figures, REVTeX

Magnetic Flux Tube Reconnection: Tunneling Versus Slingshot

The discrete nature of the solar magnetic field as it emerges into the corona through the photosphere indicates that it exists as isolated flux tubes in the convection zone, and will remain as discrete flux tubes in the corona until it collides and reconnects with other coronal fields. Collisions of these flux tubes will in general be three dimensional, and will often lead to reconnection, both rearranging the magnetic field topology in fundamental ways, and releasing magnetic energy. With the goal of better understanding these dynamics, we carry out a set of numerical experiments exploring fundamental characteristics of three dimensional magnetic flux tube reconnection. We first show that reconnecting flux tubes at opposite extremes of twist behave very differently: in some configurations, low twist tubes slingshot while high twist tubes tunnel. We then discuss a theory explaining these differences: by assuming helicity conservation during the reconnection one can show that at high twist, tunneled tubes reach a lower magnetic energy state than slingshot tubes, whereas at low twist the opposite holds. We test three predictions made by this theory. 1) We find that the level of twist at which the transition from slingshot to tunnel occurs is about two to three times higher than predicted on the basis of energetics and helicity conservation alone, probably because the dynamics of the reconnection play a large role as well. 2) We find that the tunnel occurs at all flux tube collision angles predicted by the theory. 3) We find that the amount of magnetic energy a slingshot or a tunnel reconnection releases agrees reasonably well with the theory, though at the high resistivities we have to use for numerical stability, a significant amount of magnetic energy is lost to diffusion, independent of reconnection.Comment: 21 pages, 15 figures, submitted to Ap

High magnetic field superconducting properties of Nb3Sn films Final report

High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer

Some remarks on one-dimensional force-free Vlasov-Maxwell equilibria

The conditions for the existence of force-free non-relativistic translationally invariant one-dimensional (1D) Vlasov-Maxwell (VM) equilibria are investigated using general properties of the 1D VM equilibrium problem. As has been shown before, the 1D VM equilibrium equations are equivalent to the motion of a pseudo-particle in a conservative pseudo-potential, with the pseudo-potential being proportional to one of the diagonal components of the plasma pressure tensor. The basic equations are here derived in a different way to previous work. Based on this theoretical framework, a necessary condition on the pseudo-potential (plasma pressure) to allow for force-free 1D VM equilibria is formulated. It is shown that linear force-free 1D VM solutions, which so far are the only force-free 1D VM solutions known, correspond to the case where the pseudo-potential is an attractive central potential. A general class of distribution functions leading to central pseudo-potentials is discussed.Comment: Physics of Plasmas, accepte

Composition of Jupiter irregular satellites sheds light on their origin

Irregular satellites of Jupiter with their highly eccentric, inclined and distant orbits suggest that their capture took place just before the giant planet migration. We aim to improve our understanding of the surface composition of irregular satellites of Jupiter to gain insight into a narrow time window when our Solar System was forming. We observed three Jovian irregular satellites, Himalia, Elara, and Carme, using a medium-resolution 0.8-5.5 micro m spectrograph on the National Aeronautics and Space Administration (NASA) Infrared Telescope Facility (IRTF). Using a linear spectral unmixing model we have constrained the major mineral phases on the surface of these three bodies. Our results confirm that the surface of Himalia, Elara, and Carme are dominated by opaque materials such as those seen in carbonaceous chondrite meteorites. Our spectral modeling of NIR spectra of Himalia and Elara confirm that their surface composition is the same and magnetite is the dominant mineral. A comparison of the spectral shape of Himalia with the two large main C-type asteroids, Themis (D 176 km) and Europa (D 352 km), suggests surface composition similar to Europa. The NIR spectrum of Carme exhibits blue slope up to 1.5 microm and is spectrally distinct from those of Himalia and Elara. Our model suggests that it is compositionally similar to amorphous carbon. Himalia and Elara are compositionally similar but differ significantly from Carme. These results support the hypotheses that the Jupiter irregular satellites are captured bodies that were subject to further breakup events and clustered as families based on their similar physical and surface compositions