What Laboratory-Produced Plasma Structures Can Contribute to the Understanding of Cosmic Structures Both Large and Small

The tradition of the classical 1901 work by Birkeland [1] on aurora phenomena by laboratory terrella experiments was resumed by Alfvén [2], Cowling [3], Ferraro et al. [4], and by Bennett [5] in his terrella experiments. In 1954 [6] when experimenters accidentally produced in the laboratory structures later identified as diamagnetic vortex filaments, and in 1961 [7] when filaments, later identified as current-carrying paramagnetic plasma vortex structures (which are both electric motors and dynamos), were observed in the Z and theta-pinch experiments, this tradition was being further reestablished. It has been successfully argued [6], [8], [11], [20] that both of these types of vortices are force-free minimum-free-energy structures that spontaneously spring to life as readily as do thousands of spherical bubbles and water droplets during the splash of a breaking water wave. The Birkeland aurora filaments are a hybrid combination of these two basic types (paramagnetic and diamagnetic) of plasma vortices. It is to be expected that such structures on a cosmic scale play an important role in the cosmos, and indeed they do in the formation of galaxies, stars, binary stars, solar systems, solar prominences, solar flares, solar wind, comet tails, cosmic "strings" in the Crab nebula, string-like galactic clusters, expansion of the Universe, giant galactic jets, cosmic rays, sunspots, vortex rolls in sunspot penumbra, twinkling of radio stars by the density fluctuations in the ionosphere, turbulence at the interface between the solar wind and the earth's magnetosphere, etc.     

Continuous matter creation and the acceleration of the universe: the growth of density fluctuations

Cosmologies including continuous matter creation are able to reproduce the main properties of the standard ΛCDM model, in particular in cases where the particle and entropy production rates are equal. These specific models, characterized by a mass density equal to the critical value, behave like the standard ΛCDM model at early times whereas their late evolution is similar to the steady-state cosmology. The maximum amplitude of density fluctuations in these models depends on the adopted creation rate, related here to the parameter Ω _v and this limitation could be a difficulty for the formation of galaxies and large-scale structure in this class of universe. Additional problems are related with predictions either of the random peculiar velocities of galaxies or the present density of massive clusters of galaxies, both being largely overestimated with respect to observational data.     

Magnetic Vortex Tubes in Astrophysics

The viscous forces on electrons and ions in a differentially rotating plasma drive an azimuthal current density j?, with axial magnetic field Bz which is shown to be proportional to plasma vorticity. Field strengths in agreement with those observed for both stars and galaxies are obtained, assuming that reactive forces prevent radial drifts of electrons or ions. Hierarchical vorticity is required in order to reconcile the small-scale length required for field changes with the large-scale length of observed fields. A vortex tube with magnetic field (magnetic vortex tube-MVT) becomes the basic entity for the origin of magnetic fields. Twisting of field lines by differential rotation causes (1?,Bz,) ?(jz, B?,). When jzB?, > j?, Bz the MVT suffers magnetic pinch, and the axial current in the pinch flows through a cylindrical sheath with a radial electric field due to plasma polarization. An instability of drift velocity denudes a length R of the current channel of free charges, and the inductively maintained current then requires a displacement current in R and hence a growing axial electric field Ez, Ez is limited by transfer of the energy in B?, to Ez, and thereafter the energy oscillates between the fields. On the stellar scale, evidence for polar MVT's comes from young stars with bipolar outflows of gas and jets. It is argued that end-on viewing of polar MVT's accounts for the kilogauss fields of Ap stars and the 1-100-MG fields of magnetic white dwarfs.     

Primordial magnetogenesis

Magnetic fields appear everywhere in the universe. From stars and galaxies, all the way to galaxy clusters and remote protogalactic clouds, magnetic fields of considerable strength and size have been repeatedly observed. Despite their widespread presence, however, the origin of cosmic magnetic fields is still a mystery. The galactic dynamo is believed capable of amplifying weak magnetic seeds to strengths like those measured in ours and other galaxies. But the question is where do these seed fields come from? Are they a product of late, post-recombination, physics or are they truly cosmological in origin? The idea of primordial magnetism is attractive because it makes the large-scale magnetic fields, especially those found in early protogalactic systems, easier to explain. As a result, a host of different scenarios have appeared in the literature. Nevertheless, early magnetogenesis is not problem-free, with a number of issues remaining open and a matter of debate. We review the question of the origin of primordial magnetic fields and consider the limits set on their strength by the current observational data. The various mechanisms of pre-recombination magnetogenesis are presented and their advantages and shortcomings are debated. We consider both classical and quantum scenarios, that operate within as well as outside the standard model, and also discuss how future observations could be used to decide whether the large-scale magnetic fields we see in the universe today are truly primordial or not.     

Time development of two and three-dimensional self-gravitating system using initial Dirac delta function distribution

It is shown that it is possible to extend perturbation calculations used in finding the solutions to the coupled Vlasov-Poisson equations, specifically the time evolution of density, for the one-dimensional gravitational gas to two and three dimensions. An example using initial Dirac delta distribution and Maxwellian velocity distribution is given. We reproduce main features of the one-dimensional model such as formation of inhomogeneities and also quantitatively and qualitatively new results in the higher dimensions demonstrating how galaxies and stars could be formed in the early universe.     

Critical dynamics of gauge systems: spontaneous vortex formation in 2D superconductors

We examine the formation of vortices during the nonequilibrium relaxation of a high-temperature initial state of an Abelian-Higgs system. We equilibrate the scalar and gauge fields using gauge-invariant Langevin equations and relax the system by instantaneously removing thermal fluctuations. For couplings near critical, kappa(c) = square root[lambda]/e = 1, we observe the formation of large clusters of like-sign magnetic vortices. Their appearance has implications for the dynamics of the phase transition, for the distribution of topological defects, and for late-time phase ordering kinetics. We offer explanations for both the observed vortex densities and vortex configurations.     

The Persistent Problem of Spiral Galaxies

The current explanation for spiral galaxies is that density waves in a spiral form rotate through the disks of these galaxies, continually forming new arms of hot bright stars and excited gas. The discussion here shows that many observed properties of spiral galaxies contradict this assumed density wave mechanism. Alternatively, it has been clear since the early 1950's that galaxies characteristically eject material from their nuclei. A number of astronomers have presented evidence that it is those ejections from the central regions of rotating galaxies that are responsible for the spiral arms. The evidence is reviewed and evaluated here, and it is concluded that the form and nature of the arms, their magnetic fields and rotational velocity characteristics, can best be explained by ejections of material, including plasma, from which the spiral arm stars are formed. This conclusion furnishes an answer to the long-standing problem of how the magnetic fields arise in the outer regions of spirals. Perhaps most importantly, the formation and renewal of spiral arms by ejection of plasma does not require them to be in rotation only under the pull of gravitational forces. If rotational energy is transferred to outer regions by ejections, the current interpretation of rotation curves may overestimate masses of spiral galaxies. If the problem of "missing mass" is diminished, so is the necessity for exotic suggestions to account for this undetected matter.     

Two-dimensional mesoscopic vortex clusters in a superconducting ring: Shell structure and melting

The structure and phase transitions in the mesoscopic system of vortices in a quasi-two-dimensional superconducting ring are investigated. The shell structure of the mesoscopic system of vortices is studied, and its variation with the number of vortices and the parameters of the superconducting ring is analyzed. Two mechanisms of formation of new shells in vortex clusters with an increasing number of vortices in an increasing magnetic field are discovered: the generation of a new shell in a cluster and the splitting of the internal shell into two shells. The melting of vortex clusters and their thermodynamic parameters are analyzed using the Monte Carlo method. It is found that the melting of shell-type clusters occurs in two stages, orientation melting taking place at the lower temperature (during which nearly crystalline adjacent shells start rotating relative to each other) and blurring of the vortex structure occurring at the higher temperature. The shells obtained by splitting upon an increase in the number of vortices do not participate in orientational melting. The two-stage form of melting is associated with the smaller height of potential barriers being surmounted during the rotation of shells relative to one another as compared to the barrier for vortices jumping from one shell to another.     

Spontaneous splitting of a quadruply charged vortex

We studied the splitting instability of a quadruply charged vortex both experimentally and theoretically. The density defect, which is a signature of the vortex core, is experimentally observed to deform into a linear shape. The deformed defect is theoretically confirmed to be an array of four linearly aligned singly charged vortices. The array of vortices rotates and precesses simultaneously with different angular velocities. The initial state of the system is not rotationally symmetric, which enables spontaneous splitting without external perturbations.     

色味连锁夸克物质中的涡旋

夸克物质在不同的温度和重子数密度下表现出丰富的相结构。高密低温情况下,夸克物质的基态是色味连锁相。介绍了金兹堡-朗道理论以及色味连锁夸克物质中的各种涡旋态（特别是准超流涡旋）,并讨论了磁场和自转对准超流涡旋的的影响。由于致密星核心内部有可能形成准超流涡旋,这一结果对致密星体的研究具有现实意义。如果将温度、夸克质量等因素考虑在内,研究夸克物质中涡旋结构的性质将为诸如致密星物理实验等相关的领域提供新的视角。The quark matter exhibits a rich phase structure at different temperatures and baryon number densities. At high baryon density and low temperature, the color-flavor locked phase is believed to be the ground state of the quark matter. We present an introduction to various vortices in the color-flavor locked quark matter, especially for the semi-superfluid vortices, and their research method (Ginzburg-Landau method). The influence of magnetic field and rotation on properties of these vortices is discussed. Due to the possibility of forming a semi-superfluid vortex in the core of the dense star, this result is of practical significance in the study of dense stars. If considering other factors, such as temperature and quark mass, study of the vortex structure properties in the quark matter could provide new perspectives for related fields, for instance dense star physics.     

Dark Matter as a Cosmic Bose-Einstein Condensate and Possible Superfluid

Dark matter arising from spontaneous symmetry breaking of a neutral scalar field coupled to gravity comprises ultra low mass bosons with a Bose-Einstein condensation temperature far above the present background temperature. Assuming galactic halos to consist of a Bose-Einstein condensate of astronomical extent, we calculate the condensate coherence length, transition temperatures, mass distribution, and orbital velocity curves, and deduce the particle mass and number density from the observed rotation curves for the Andromeda and Triangulum galaxies. We also consider the possibility of superfluid behaviour in the halos of rotating galaxies, and estimate the critical angular frequency and line density for formation of quantised vortices.     

The history of star formation in the universe

Our primary means of studying how galaxies form and evolve over cosmic time is through measurements of the rate at which massive stars are born in galaxies per unit comoving volume of the universe. Only recently have the most distant, most massively star-forming galaxies in the universe even been discovered, and these discoveries are challenging the standard cosmological scenario in which galaxies form hierarchically, with low-mass objects collapsing first and then merging to form larger and larger systems over cosmic time. We now know that these incredibly luminous galaxies, which have all but vanished in the local universe, are cocooned in dust, hiding them from optical view. They can only be detected at long wavelengths where the dust reradiates the starlight that it has absorbed. In this review, I trace the spectacular progress that has been made over the last decade towards understanding the cosmic history of star formation, with a particular emphasis on the important role of dusty sources in that history.     

Magnetic vortex gyration mediated by point-contact position

Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eigenfrequency, trajectory, velocity and the time for a magnetic vortex to obtain the steady gyration are analyzed. Simulation results reveal that the magnetic vortices in larger and thinner nanodisks can achieve a lower-frequency gyration at a lower current density in a shorter time. However, the magnetic vortices in thicker nanodisks need a higher current density and longer time to attain steady gyration but with a higher eigenfrequency. We also find that the point-contact position exerts different influences on these parameters in different nanodisks, which contributes to the control of the magnetic vortex gyration. The conclusions of this paper can serve as a theoretical basis for designing nano-oscillators and microwave frequency modulators.     

Vortex chains induced by anisotropic spin-orbit coupling and magnetic field in spin-2 Bose-Einstein condensates

We investigate the anisotropic spin-orbit coupled spin-2 Bose-Einstein condensates with Ioffe-Pritchard magnetic field. With nonzero magnetic field, anisotropic spin-orbit coupling will introduce several vortices and further generate a vortex chain. Inside the vortex chain, the vortices connect to each other, forming a line along the axis. The physical nature of the vortex chain can be explained by the particle current and the momentum distribution. The vortex number inside the vortex chain can be influenced via varying the magnetic field. Through adjusting the anisotropy of the spin-orbit coupling, the direction of the vortex chain is changed, and the vortex lattice can be triggered. Moreover, accompanied by the variation of the atomic interactions, the density and the momentum distribution of the vortex chain are affected. The realization and the detection of the vortex chain are compatible with current experimental techniques.     

Ordered states and structural transitions in a system of Abrikosov vortices with periodic pinning

A system of Abrikosov vortices in a quasi-two-dimensional HTSC plate is considered for various periodic lattices of pinning centers. The magnetization and equilibrium configurations of the vortex density for various values of external magnetic field and temperature are calculated using the Monte Carlo method. It is found that the interaction of the vortex system with the periodic lattice of pinning centers leads to the formation of various ordered vortex states through which the vortex system passes upon an increase or a decrease in the magnetic field. It is shown that ordered vortex states, as well as magnetic field screening processes, are responsible for the emergence of clearly manifested peaks on the magnetization curves. Extended pinning centers and the effect of multiple trapping of vortices on the behavior of magnetization are considered. Melting and crystallization of the vortex system under the periodic pinning conditions are investigated. It is found that the vortex system can crystallize upon heating in the case of periodic pinning.     

Formation of multiple-flux-quantum vortices in mesoscopic superconductors from simulations of calorimetric, magnetic, and transport properties

Because of strong flux confinement in mesoscopic superconductors, a "giant" vortex may appear in the ground state of the system in an applied magnetic field. This multiquanta vortex can then split into individual vortices (and vice versa) as a function of, e.g., applied current, magnetic field, or temperature. Here we show that such transitions can be identified by calorimetry, as the formation or splitting of a giant vortex results in a clear jump in measured heat capacity versus external drive. We attribute this phenomenon to an abrupt change in the density of states of the quasiparticle excitations in the vortex core(s), and further link it to a sharp change of the magnetic susceptibility at the transition--proving that the formation of a giant vortex can also be detected by magnetometry.     

Confronting dark energy models mimicking ΛCDM epoch with observational constraints: Future cosmological perturbations decay or future Rip?

We confront dark energy models which are currently similar to ΛCDM theory with observational data which include the SNe data, matter density perturbations and baryon acoustic oscillations data. DE cosmology under consideration may evolve to Big Rip, type II or type III future singularity, or to Little Rip or Pseudo-Rip universe. It is shown that matter perturbations data define more precisely the possible deviation from ΛCDM model than consideration of SNe data only. The combined data analysis proves that DE models under consideration are as consistent as ΛCDM model. We demonstrate that growth of matter density perturbations may occur at sufficiently small background density but still before the possible disintegration of bound objects (like clusters of galaxies, galaxies, etc.) in Big Rip, type III singularity, Little Rip or Pseudo-Rip universe. This new effect may bring the future universe to chaotic state well before disintegration or Rip.     

Cosmological magnetic fields

Magnetic fields are observed not only in stars, but in galaxies, clusters, and even high redshift Lyman-α systems. In principle, these fields could play an important role in structure formation and also affect the anisotropies in the cosmic microwave background radiation (CMB). The study of cosmological magnetic fields aims not only to quantify these effects on large-scale structure and the CMB, but also to answer one of the outstanding puzzles of modern cosmology: when and how do magnetic fields originate? They are either primoridial, i.e. created before the onset of structure formation, or they are generated during the process of structure formation itself.     

Non-equilibrium in cosmology

All the non-trivial features of the Universe we see around us, such as particles, stars, galaxies, and clusters of galaxies, are the result of non-equilibrium processes in the cosmic evolution. These lectures aim to provide some general background in cosmology and to examine specific, and notable, examples of departures from thermal equilibrium. They are organized as follows: 1) Overview of the thermal history of the Universe after the Big Bang: the relevant time-scales and the mechanism of particle decoupling from the themal bath; 2) Explicit examples of cosmic relics: nucleosynthesis, photons and the cosmic microwave background, neutrinos, and cold dark matter; 3) Baryogenesis: the generation of the baryon asymmetry of the Universe; 4) The formation of cosmic structures (galaxies, clusters of galaxies): from the Vlasov equation to the renormalization group.