Theories on the Formation and Evolution of Black Holes & Galaxies

Conventional theory suggests that black holes are singularities of enormous mass-density: matter compressed beyond imagination due to extreme mass-based gravitational forces and possessing so much mass-based gravity that light itself cannot escape them. As an alternative to convention, this paper builds on the theories of fire-tornado accretion cylinder vortex forces and colossal magnetic pressure spawned within (previously described by the authors in their paper on ~2D planar celestial kinematics), and analyzes them in more detail specifically for black holes and the formation / evolution of galaxies. Several interesting charge-distribution and associated electromagnetic field components will be utilized in the modeling. To demonstrate concept, the proposed forces during formation and evolution will be computationally modeled and translated into visual simulations in 4-D space-time using C# programming in the Unity operating platform.

Generation of Cold Magnetized Relativistic Plasmas at the Rear of Thin Foils Irradiated by Ultra-High-Intensity Laser Pulses

A scheme to generate magnetized relativistic plasmas in a laboratory setting is proposed. It is based on the interaction of ultra-high-intensity sub-picosecond laser pulses with few-micron-thick foils or films. By means of Particle-In-Cell simulations, it is shown that energetic electrons produced by the laser and evacuated at the rear of the target trigger an expansion of the target, building up a strong azimuthal magnetic field. It is shown that in the expanding plasma sheath, a ratio of the magnetic pressure and the electron rest-mass energy density exceeds unity, whereas the plasma pressure is lower than the magnetic pressure and the electron gyroradius is lower than the plasma dimension. This scheme can be utilized to study astrophysical extreme phenomena such as relativistic magnetic reconnection in laboratory.

Domains of Magnetic Pressure Balance in Parker Solar Probe Observations of the Solar Wind

The Parker Solar Probe (PSP) spacecraft is performing the first in situ exploration of the solar wind within 0.2 au of the Sun. Initial observations confirmed the Alfvénic nature of aligned fluctuations of the magnetic field B and velocity V in solar wind plasma close to the Sun, in domains of nearly constant magnetic field magnitude ∣ B ∣, i.e., approximate magnetic pressure balance. Such domains are interrupted by particularly strong fluctuations, including but not limited to radial field (polarity) reversals, known as switchbacks. It has been proposed that nonlinear Kelvin–Helmholtz instabilities form near magnetic boundaries in the nascent solar wind leading to extensive shear-driven dynamics, strong turbulent fluctuations including switchbacks, and mixing layers that involve domains of approximate magnetic pressure balance. In this work we identify and analyze various aspects of such domains using data from the first five PSP solar encounters. The filling fraction of domains, a measure of Alfvénicity, varies from median values of 90% within 0.2 au to 38% outside 0.9 au, with strong fluctuations. We find an inverse association between the mean domain duration and plasma β. We examine whether the mean domain duration is also related to the crossing time of spatial structures frozen into the solar wind flow for extreme cases of the aspect ratio. Our results are inconsistent with long, thin domains aligned along the radial or Parker spiral direction, and compatible with isotropic domains, which is consistent with prior observations of isotropic density fluctuations or flocculae in the solar wind.

Функциональные возможности электромагнитно-акустических преобразований в токовом режиме в металлическом расплаве

The paper deals with a symmetric problem on the base of physically substantiated estimates of the processes of electromagnetic-acoustic transformations (EMAT) of energy during the flow of an electric current through a melt, the key parameters of the open problem of the system "Power source parameters – Parameters of the magnetic field and magnetic pressure of the skin layer – Parameters of acoustic disturbances". It was shown that the key parameter when formulating the EMAT problem in technological applications is the geometry of the container with the object of processing and the material of the form. And when solving the problem, they are the parameter of the skin layer and the time dependence of the discharge current. It was established that a part of energy during the formation of the magnetic pressure in the skin layer from the amount of the energy stored in the capacitor bank of the pulse current generator is on the order of 10-4–10-2. The value of this part depends on the period of the discharge current and is proportional to the T1/2. When acoustic disturbances propagate in a melt, the main share of energy losses is determined by the difference in the acoustic stiffness of the melt and the shape of materials. The frequency spectra of the pressure of sound waves at the parameters selected for the analysis can cover the range of up to hundreds kHz, which is a good reason for the realization of resonance effects and the active formation of dissipative structures. Attention is focused on the fact that EMAT effects are manifested in the melt not only under the influence of an acoustic field, but also under that of an electromagnetic one in the skin layer. They are separated in time, but the acoustic field can occupy the entire volume of the melt and its effect is longer in time.

Effect of shaping on turbulent dynamics in reversed-field pinch simulations

We study the influence of the shape of the plasma container on the dynamics of the reversed-field pinch (RFP). The geometries we consider are periodic cylinders with elliptical and circular-shaped cross-sections. Numerical simulations of fully nonlinear viscoresistive magnetohydrodynamics are carried out to illustrate how the plasma dynamics is affected by shaping. It is shown that independent of the plasma shape, the quantity $\beta$ , comparing the hydrodynamic pressure to the magnetic pressure, decreases for increasing values of the Lundquist number, but the pressure gradient fluctuations remain roughly constant, when compared to the Lorentz force. Different elliptical shapes of the cross-section of the domain lead to the excitation of different toroidal (or axial) magnetic and dynamic modes. Furthermore, it is found that in a geometry with circular cross-section, a significant local poloidal angular momentum is observed, absent in the geometries with elliptical cross-section. Because the confinement is dominantly determined by plasma movement, and the dynamics of the velocity and magnetic field are modified by the modification of the geometry, shaping can thus affect the performance of RFP devices.

Magnetic Field Gradient Across the Flank Magnetopause

Magnetic pressure inside the magnetopause is usually balanced with a sum of thermal plasma and magnetic pressures on the magnetosheath side. However, observations reveal that the magnetosheath magnetic field can be frequently larger than that in the magnetosphere (inverse magnetic field gradient across the magnetopause), and thus, the enhanced pressure from the magnetosheath side seems to be uncompensated. Such events are rare in the subsolar region, but their occurrence rate increases toward flanks. The analysis, based on statistical processing of about 35,000 THEMIS magnetopause crossings collected in the course of the years 2007–2017, shows that these events are more frequently observed under enhanced geomagnetic activity that is connected with a strong southward IMF. Case studies reveal that such a state of the magnetopause boundary layers can persist for several hours. This study discusses conditions and mechanisms keeping the pressure balance across the magnetopause under these conditions.

Decayless Kink Oscillations Excited by Random Driving: Motion in Transitional Layer

In this article we study the plasma motion in the transitional layer of a coronal loop randomly driven at one of its footpoints in the thin-tube and thin-boundary-layer (TTTB) approximation. We introduce the average of the square of a random function with respect to time. This average can be considered as the square of the oscillation amplitude of this quantity. Then we calculate the oscillation amplitudes of the radial and azimuthal plasma displacement as well as the perturbation of the magnetic pressure. We find that the amplitudes of the plasma radial displacement and the magnetic-pressure perturbation do not change across the transitional layer. The amplitude of the plasma radial displacement is of the same order as the driver amplitude. The amplitude of the magnetic-pressure perturbation is of the order of the driver amplitude times the ratio of the loop radius to the loop length squared. The amplitude of the plasma azimuthal displacement is of the order of the driver amplitude times $\text{Re}^{1/6}$ Re 1 / 6 , where Re is the Reynolds number. It has a peak at the position in the transitional layer where the local Alfvén frequency coincides with the fundamental frequency of the loop kink oscillation. The ratio of the amplitude near this position and far from it is of the order of $\ell$ ℓ , where $\ell$ ℓ is the ratio of thickness of the transitional layer to the loop radius. We calculate the dependence of the plasma azimuthal displacement on the radial distance in the transitional layer in a particular case where the density profile in this layer is linear.

Asymptotic Shallow Models Arising in Magnetohydrodynamics

In this paper, we derive new shallow asymptotic models for the free boundary plasma-vacuum problem governed by the magnetohydrodynamic equations which are vital when describing large-scale processes in flows of astrophysical plasma. More precisely, we present the magnetic analogue of the 2D Green–Naghdi equations for water waves under a weak magnetic pressure assumption in the presence of weakly sheared vorticity and magnetic currents. Our method is inspired by ideas for hydrodynamic flows developed in Castro and Lannes (2014) to reduce the three-dimensional dynamics of the vorticity and current to a finite cascade of two dimensional equations which can be closed at the precision of the model.

Turbulence characteristics of Solar Prominences due to Rayleigh Taylor Instabilities

<p>The purpose of our study is to deepen our understanding on the turbulence that arises from Rayleigh Taylor Instabilities in quiescent solar prominences. Quiescent prominences in the solar corona are cool and dense condensates that show internal dynamics over a wide range of spatial and temporal scales. These dynamics are dominated by vertical flows in the prominence body where the mean magnetic field is predominantly in the horizontal direction and the magnetic pressure suspends the dense prominence material. We perform numerical simulations using  MPI-AMRVAC (http://amrvac.org) to study the Rayleigh Taylor Instabilitiy at the prominence-corona transition region using the Ideal-magentohydrodyamics approach. High resolution simulations achieve a resolution of ∼23 km for ∼21 min transitioning from a multi-mode perturbation instability to the non-linear regime and finally a fully turbulent prominence. We use statistical methods to quantify the rich dynamics in quiescent prominence as being indicative of turbulence.</p>