Protostellar Jet and Outflow in the Collapsing Cloud Core

We investigate the driving mechanism of outflows and jets in star formation process using resistive MHD nested grid simulations. We found two distinct flows in the collapsing cloud core: Low-velocity outflows (sim 5 km/s) with a wide opening angle, driven from the first adiabatic core, and high-velocity jets (sim 50 km/s) with good collimation, driven from the protostar. High-velocity jets are enclosed by low-velocity outflow. The difference in the degree of collimation between the two flows is caused by the strength of the magnetic field and configuration of the magnetic field lines. The magnetic field around an adiabatic core is strong and has an hourglass configuration. Therefore, the low-velocity outflow from the adiabatic core are driven mainly by the magnetocentrifugal mechanism and guided by the hourglass-like field lines. In contrast, the magnetic field around the protostar is weak and has a straight configuration owing to Ohmic dissipation in the high-density gas region. Therefore, high-velocity jet from the protostar are driven mainly by the magnetic pressure gradient force and guided by straight field lines. Differing depth of the gravitational potential between the adiabatic core and the protostar cause the difference of the flow speed. Low-velocity outflows correspond to the observed molecular outflows, while high-velocity jets correspond to the observed optical jets. We suggest that the protostellar outflow and the jet are driven by different cores (the first adiabatic core and protostar), rather than that the outflow being entrained by the jet.Comment: To appear in the proceedings of the "Protostellar Jets in Context" conference held on the island of Rhodes, Greece (7-12 July 2008

Direct Imaging of Spatially Modulated Superfluid Phases in Atomic Fermion Systems

It is proposed that the spatially modulated superfluid phase, or the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state could be observed in resonant Fermion atomic condensates which are realized recently. We examine optimal experimental setups to achieve it by solving Bogoliubov-de Gennes equation both for idealized one-dimensional and realistic three-dimensional cases. The spontaneous modulation of this superfluid is shown to be directly imaged as the density profiles either by optical absorption or by Stern-Gerlach experiments.Comment: 4 pages, 3 figure

Topological Structure of a Vortex in Fulde-Ferrell-Larkin-Ovchinnikov State

We find theoretically that the vortex core in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is quite different from the ordinary core by a simple topological reason. The intersection point of a vortex and nodal plane of the FFLO state empties the excess spins. This leads to observable consequences in the spatial structure of the spontaneous magnetization. We analyze this topological structure based on the low lying excitation spectrum by solving microscopic Bogoliubov-de Gennes equation to clarify its physical origin.Comment: 4 pages, 4 figure

Magnetic skyrmion lattices in heavy fermion superconductor UPt3

Topological analysis of nearly SO(3)_{spin} symmetric Ginzburg--Landau theory, proposed for UPt$_{3}$ by Machida et al, shows that there exists a new class of solutions carrying two units of magnetic flux: the magnetic skyrmion. These solutions do not have singular core like Abrikosov vortices and at low magnetic fields they become lighter for strongly type II superconductors. Magnetic skyrmions repel each other as $1/r$ at distances much larger then the magnetic penetration depth $\lambda$, forming a relatively robust triangular lattice. The magnetic induction near $H_{c1}$ is found to increase as $(H-H_{c1})^{2}$. This behavior agrees well with experiments.Comment: 4 pages, 2 figures, 2 column format; v2:misprint in the title is correcte

A Non-Scaling FFAG Gantry Design for the PAMELA Project

A gantry is re­quired for the PAMELA pro­ject using non-scal­ing Fixed Field Al­ter­nat­ing Gra­di­ent (NS-FFAG) mag­nets. The NS-FFAG prin­ci­ple of­fers the pos­si­bil­i­ty of a gantry much small­er, lighter and cheap­er than con­ven­tion­al de­signs, with the added abil­i­ty to ac­cept a wide range of fast chang­ing en­er­gies. This paper will build on pre­vi­ous work to in­ves­ti­gate a de­sign which could be used for the PAMELA pro­ject

Disk formation during collapse of magnetized protostellar cores

In the context of star and planet formation, understanding the formation of disks is of fundamental importance. Previous studies found that the magnetic field has a very strong impact on the collapse of a prestellar cloud, particularly in possibly suppressing the formation of a disk even for relatively modest values of the magnetic intensity. Since observations infer that cores have a substantial level of magnetization, this raises the question of how disks form. However, most studies have been restricted to the case in which the initial angle, $\alpha$, between the magnetic field and the rotation axis equals 0$^\circ$. We explore and analyse the influence of non aligned configurations on disk formation. We perform 3D ideal MHD, AMR numerical simulations for various values of $\mu$, the ratio of the mass-to-flux to the critical mass-to-flux, and various values of $\alpha$. We find that disks form more easily as $\alpha$ increases from 0 to 90$^\circ$. We propose that as the magnetized pseudo-disks become thicker with increasing $\alpha$, the magnetic braking efficiency is lowered. We also find that even small values of $\alpha$ ($\simeq$ 10-20$^\circ$) show significant differences with the alligned case. Within the framework of ideal MHD and for our choice of initial conditions, centrifugally supported disks cannot form for values of $\mu$ smaller than $\simeq$3, if the magnetic field and the rotation axis are perpendicular, and smaller than about $\simeq$5-10 when they are perfectly aligned.Comment: accepted for publication in A&

Vortex states in superconductors with strong Pauli-paramagnetic effect

Using the quasiclassical theory, we analyze the vortex structure of strong-paramagnetic superconductors.There, induced paramagnetic moments are accumulated exclusively around the vortex core. We quantitatively evaluate the significant paramagnetic effect in the H-dependence of various quantities, such as low temperature specific heat, Knight shift, magnetization and the flux line lattice (FLL) form factor. The anomalous H-dependence of the FLL form factor observed by the small angle neutron scattering in CeCoIn_5 is attributable to the large paramagnetic contribution.Comment: 7 pages, 5 figure

Specific heat and low-lying excitations in the mixed state for a type II superconductor

Low temperature behavior of the electronic specific heat $C(T)$ in the mixed state is by the self-consistent calculation of the Eilenberger theory. In addition to $\gamma T$-term ($\gamma$ is a Sommerfeld coefficient), $C(T)$ has significant contribution of $T^2$-term intrinsic in the vortex state. We identify the origin of the $T^2$-term as (i) V-shape density of states in the vortex state and (ii) Kramer-Pesch effect of vortex core shrinking upon lowering $T$. These results both for full-gap and line node cases reveal that the vortex core is a richer electronic structure beyond the normal core picture.Comment: Accepted in Phys. Rev. B. 5 pages, 5 figure