Effect Of Strong Magnetic Field Research Articles

Effects of strong magnetic field on moment of inertia and surface gravitational redshift in neutron star

Research on the properties of neutron stars with strong magnetic fields is of great significance in constraining the equation of state and revealing the real distribution of magnetic fields in neutron stars. The main macroscopic properties of the traditional neutron star matter under <i>β</i> equilibrium condition are studied within the relativistic mean field theory through using the GL91 parameter set by considering the strong magnetic field. It is found that the onset of the strong magnetic field leads to the stiffened equation of state of the traditional neutron star matter. The maximum mass of the traditional neutron star grows from 2.111 M<sub>⊙</sub> to 3.081 M<sub>⊙</sub>, the radius of the fixed mass traditional neutron star grows larger with the increase of internal magnetic field, which makes traditional neutron star become less dense. The strong magnetic field can also reduce the surface gravitational redshift and strengthen the moment of inertia of the traditional neutron star matter. In addition, the theoretical ranges of the surface gravitational redshift and the moment of inertia for the four massive PSRs J1614-2230, J0348+0432, J0740+6620 and J2215-5135, and the 2.50 M<sub>⊙</sub> − 2.67 M<sub>⊙</sub> compact object in the binary merger event GW190814 are also given. The results show that the ranges of the surface redshift become narrower, while the scopes of the moment of inertia widen as the magnetizing field increases in the five stars.

Recent results on azimuthal anisotropies of open heavy-flavour particles with ALICE at the LHC

Heavy quarks are unique probes to investigate the properties of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions. The ALICE Collaboration measured the D-meson elliptic flow, ν2, in Pb–Pb collisions at sNN=5.02TeV to study the participation of the low and intermediate transverse momentum (pT) charm quarks in the collective expansion of the system. The charm-quark dynamic in the QGP is further investigated through the Event Shape Engineering (ESE) technique. Furthermore, the effect of unprecedented strong magnetic field produced in heavy-ion collisions is studied by measuring the charged-dependent directed flow (ν1) of D0 mesons for the first time at the LHC. Recent results of azimuthal anisotropy of open heavy-flavour decay electrons and muons in p–Pb collisions at sNN=5.02TeV and sNN=8.16TeV, respectively, are also shown.

The history of dynamics and stellar feedback revealed by the H I filamentary structure in the disk of the Milky Way

We present a study of the filamentary structure in the emission from the neutral atomic hydrogen (HI) at 21 cm across velocity channels in the 40′′ and 1.5-km s−1 resolution position-position-velocity cube, resulting from the combination of the single-dish and interferometric observations in The HI/OH/recombination-line survey of the inner Milky Way. Using the Hessian matrix method in combination with tools from circular statistics, we find that the majority of the filamentary structures in the HI emission are aligned with the Galactic plane. Part of this trend can be assigned to long filamentary structures that are coherent across several velocity channels. However, we also find ranges of Galactic longitude and radial velocity where the HI filamentary structures are preferentially oriented perpendicular to the Galactic plane. These are located (i) around the tangent point of the Scutum spiral arm and the terminal velocities of the Molecular Ring, around l ≈ 28° and vLSR ≈ 100 km s−1, (ii) toward l ≈ 45° and vLSR ≈ 50 km s−1, (iii) around the Riegel-Crutcher cloud, and (iv) toward the positive and negative terminal velocities. A comparison with numerical simulations indicates that the prevalence of horizontal filamentary structures is most likely the result of large-scale Galactic dynamics and that vertical structures identified in (i) and (ii) may arise from the combined effect of supernova (SN) feedback and strong magnetic fields. The vertical filamentary structures in (iv) can be related to the presence of clouds from extra-planar HI gas falling back into the Galactic plane after being expelled by SNe. Our results indicate that a systematic characterization of the emission morphology toward the Galactic plane provides an unexplored link between the observations and the dynamical behavior of the interstellar medium, from the effect of large-scale Galactic dynamics to the Galactic fountains driven by SNe.

Neutron star inner crust: Effects of rotation and magnetic fields

We study the role of the pasta phases on the properties of rotating and magnetized neutron stars. In order to investigate such systems, we make use of two different relativistic mean-field unified inner-crust--core equations of state, with a different density dependence of the symmetry energy, and an inner crust computed within a Thomas-Fermi calculation. Special attention is given to the crust-core transition density, and the pasta phases effects on the global properties of stars. The effects of strong magnetic fields and fast rotation are computed by solving the Einstein-Maxwell equations self-consistently, taking into account anisotropies induced by the centrifugal and the Lorentz force. The location of the magnetic field neutral line and the maximum of the Lorentz force on the equatorial plane are calculated. The conditions under which they fall inside the inner crust region are discussed. We verified that models with a larger symmetry energy slope show more sensitivity to the variation of the magnetic field. One of the maxima of the Lorentz force, as well as the neutral line, and for a certain range of frequencies, fall inside the inner crust region. This may have consequences in the fracture of the crust, and may help explain phenomena associated with star quakes.

Effect of magnetic field on the charge and thermal transport properties of hot and dense QCD matter

We have studied the effect of strong magnetic field on the charge and thermal transport properties of hot QCD matter at finite chemical potential. For this purpose, we have calculated the electrical conductivity (sigma _mathrm{el}) and the thermal conductivity (kappa ) using kinetic theory in the relaxation time approximation, where the interactions are subsumed through the distribution functions within the quasiparticle model at finite temperature, strong magnetic field and finite chemical potential. This study helps to understand the impacts of strong magnetic field and chemical potential on the local equilibrium by the Knudsen number (Omega ) through kappa and on the relative behavior between thermal conductivity and electrical conductivity through the Lorenz number (L) in the Wiedemann–Franz law. We have observed that, both sigma _mathrm{el} and kappa get increased in the presence of strong magnetic field, and the additional presence of chemical potential further increases their magnitudes, where sigma _mathrm{el} shows decreasing trend with the temperature, opposite to its increasing behavior in the isotropic medium, whereas kappa increases slowly with the temperature, contrary to its fast increase in the isotropic medium. The variation in kappa explains the decrease of the Knudsen number with the increase of the temperature. However, in the presence of strong magnetic field and finite chemical potential, Omega gets enhanced and approaches unity, thus, the system may move slightly away from the equilibrium state. The Lorenz number (kappa /(sigma _mathrm{el} T)) in the abovementioned regime of strong magnetic field and finite chemical potential shows linear enhancement with the temperature and has smaller magnitude than the isotropic one, thus, it describes the violation of the Wiedemann–Franz law for the hot and dense QCD matter in the presence of a strong magnetic field.

Experimental Analysis of Synergetic Effect of Part-Cooled Exhaust Gas Recirculation on Magnetic Field-Assisted Combustion of Liquefied Petroleum Gas

Magnetic field-assisted combustion has been under the focus of research for the last three decades around the globe. The effects of strong uniform and gradient magnetic fields on flame development, behaviour and propagation have been studied, and their applications have been experimented on Internal Combustion Engines. The present work investigates the synergetic effect of part-cooled EGR on the magnetic field-assisted combustion of liquefied petroleum gas in a multicylinder MPFI spark-ignited engine modified for neat LPG operation. Sintered neo-delta magnets with radial magnetization pattern of four different magnetic intensities (0G, 3200G, 4800G and 6400G) are fastened to the fuel line near to the gas injector with a non-magnetic stainless steel integument to prevent any loss of magnetic intensities during the operation. A portion of the exhaust gas is channelled to an intercooler and an optimum percentage of the partially cooled gases are inducted into the inlet manifold for combustion. The experimental study concludes that the optimum flow rate of part-cooled EGR acts synergistically with the applied magnetic fields to enhance the combustion characteristics of LPG emanating an improved fuel economy of 13.8% and brake thermal efficiency of 3.9%. The increased emission of oxides of Nitrogen which is the major setback of LPG combustion can be addressed through the combined effect of part-cooled EGR and magnetic field-assisted combustion. Moreover, the reduction in stability of combustion through the recirculation of exhaust can also be balanced by the applied magnetic field.

Dynamically assisted Schwinger mechanism and chirality production in parallel electromagnetic field

We study particle and chirality production from the vacuum in the presence of a slow strong parallel electromagnetic field superimposed by a fast weak perturbative electromagnetic field. We derive an analytical formula for the particle and chirality production number based on the perturbation theory in the Furry picture. With the formula, we analytically discuss the interplay and dynamical assistance between the Schwinger mechanism and one-photon pair production and clarify effects of a parallel slow strong magnetic field. We also show that the dynamical assistance can significantly enhance chirality production, and that a sizable amount of chirality can be produced even for massive particles. Phenomenological applications including heavy-ion collisions and intense laser experiments are also discussed.

Heat and Mass Transfer Analysis of Nanofluid Flow Based on Cu, Al2O3, and TiO2 over a Moving Rotating Plate and Impact of Various Nanoparticle Shapes

The study of rotating nanofluid flows has a vital role in several applications such as in food processing, rotating machinery, cooling systems, and chemical fluid. The aims of the present work are to improve the thermophysical properties of convective flow and heat transfer for unsteady nanofluid past a moving rotating plate in the presence of ohmic, viscous dissipations, Brownian, and thermophoresis diffusion. The system is strained under the effect of strong magnetic field, and then the Hall current is considered. For this investigation, three different types of the nanoparticles Cu (copper), Al2O3 (aluminium oxide), and TiO2 (titanium dioxide) with various shapes (spherical, cylindrical, and brick) are considered, and water is used as a base nanofluid. The system governing equations are solved semianalytically using homotopy perturbation technique. In order to validate the present work, different comparisons are made under some special cases with previously published results and found an excellent agreement. It is observed that the shape of nanoparticles plays a substantial role to significantly determine the flow behaviour. Also, it can be found that the use of the cylindrical nanoparticle shape has better improvement for heat transfer rate compared with the other nanoparticle shapes.

Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions.

We report a multifrequency nuclear magnetic resonance (NMR) study of heterospin complexes [Eu(SQ)3Ln], where SQ is 3,6-di(tert-butyl)-1,2-semiquinone, L is tetrahydrofuran (THF), pyridine (Py), or 2,2'-dipyridyl (Dipy), and n is the number of diamagnetic ligands. Multifrequency NMR experiments allowed us to determine the effective paramagnetic shifts of the ligands (L = THF or Py) and the chemical equilibrium constant for [Eu(SQ)3(THF)2]. In addition, we have found a strong magnetic field effect on the NMR line broadening, giving rise to very broad NMR lines at high magnetic fields. We attribute this effect to broadening under fast exchange conditions when the NMR spectrum represents a homogeneously broadened line with a width proportional to the square of the NMR frequency difference of the free and bound forms of L. Consequently, the line width strongly increases with the magnetic field. This broadening effect allows one to determine relevant kinetic parameters, i.e., the effective exchange time. The strong broadening effect allows one to exploit the [Eu(SQ)3(THF)2] complex as an efficient shift reagent, which not only shifts unwanted NMR signals but also broadens them, notably, in high-field NMR experiments. We have also found that [Eu(SQ)3Dipy] is a thermodynamically stable complex; hence, one can study [Eu(SQ)3Dipy] solutions without special precautions. We report an X-ray structure of the [Eu(SQ)3Dipy]·C6D6 crystals that have been grown directly in an NMR tube. This shows that multifrequency NMR investigations of heterospin compound solutions not only provide thermodynamic and kinetic data for heterospin species but also can be useful for the rational design of stable heterospin complexes and optimization of synthetic approaches.

Magnetic field effect on recombination of radicals diffusing on a two-dimensional plane.

Magnetic Field Effects (MFEs) on the recombination of radicals, which diffuse on an infinite plane, are studied theoretically. The case of spin-selective diffusion-controlled recombination of Radical Pairs (RPs) starting from a random spin state is considered assuming uniform initial distribution of the radicals. In this situation, reaction kinetics is described by a time-dependent rate coefficient K(t), which tends to zero at long times. Strong MFEs on K(t) are predicted that originate from the Δg and hyperfine driven singlet-triplet mixing in the RP. The effects of spin relaxation on the magnetic field are studied, as well as the influence of the dipole-dipole interaction between the electron spins of the RP. In the two-dimensional case, this interaction is not averaged out by diffusion and it strongly affects the MFE. The results of this work are of importance for interpreting MFEs on lipid peroxidation, a magnetosensitive process occurring on two-dimensional surfaces of cell membranes.

Thermal Evolution of Neo-neutron Stars. I. Envelopes, Eddington Luminosity Phase, and Implications for GW170817

Abstract A neo-neutron star is a hot neutron star that has just become transparent to neutrinos. In a core-collapse supernova or accretion-induced collapse of a white dwarf, the neo-neutron star phase directly follows the proto-neutron star phase, about 30–60 s after the initial collapse. It will also be present in a binary neutron star merger in the case where the “born-again” hot massive compact star does not immediately collapse into a black hole. Eddington or even super-Eddington luminosities are present for some time. A neo-neutron star produced in a core-collapse supernova is not directly observable, but the one produced by a binary merger, likely associated with an off-axis short gamma-ray burst, may be observable for some time as well as when produced in the accretion-induced collapse of a white dwarf. We present a first step in the study of this neo-neutron star phase in a spherically symmetric configuration, thus ignoring fast rotation and also ignoring the effect of strong magnetic fields. We put particular emphasis on determining how long the star can sustain a near-Eddington luminosity and also show the importance of positrons and contraction energy during the neo-neutron star phase. We finally discuss the observational prospects for neutron star mergers triggered by LIGO and for accretion-induced collapse transients.

Landau damping in a strong magnetic field: Dissociation of quarkonia

In this article we have investigated the effects of strong magnetic field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and then studied the quasi-free dissociation of quarkonia due to the Landau-damping. Thermalising the Schwinger propagator for quarks in the lowest Landau levels and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Finally the inverse Fourier transform of the permittivities encrypt the effect of hot QCD medium in the presence of strong magnetic field into both real and imaginary parts of heavy quark potential. We have found that the magnetic field largely affects the large-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to its counterpart in the absence of magnetic field. The real part of the potential is thereafter solved numerically by the Schrödinger equation to obtain the energy eigenvalues and energy eigenfunctions of the charmonium states. We have noticed that in the presence of strong magnetic field, the size (r2) of J/ψ and ψ′ are swelled whereas χc gets shrunk, unless the temperature is very high. Similarly the magnetic field affects the binding of J/ψ and χc differently, i.e. it decreases the binding of J/ψ but increases for χc. On contrary the magnetic field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied the dissociation due to the Landau damping and found that the dissociation temperatures become higher in the presence of magnetic field. For example, with eB=6mπ2 the J/ψ is dissociated at 2Tc, and with eB=4mπ2 the χc is dissociated at 1.1Tc in comparison, with eB = 0 the J/ψ is dissociated at T=1.6Tc and χc is dissociated at T=0.8Tc. However, with the further increase of magnetic field the dissociation temperatures decrease.

Effect of strong magnetic field on the microstructure and mechanical-magnetic properties of AlCoCrFeNi high-entropy alloy

While there have been multiple recent reports in the literature of exceptional mechanical properties in high-entropy alloys (HEAs) which tried to tackle the barrier of the “strength-ductility trade-off”, the research of how strong the magnetic field affects mechanical and magnetic properties of HEAs is still preliminary. This paper shows that applying strong magnetic field during heat treatment can tailor the microstructure and improve both mechanical and magnetic properties of AlCoCrFeNi HEAs compared with those without the magnetic field. After applying 6 T magnetic field, the magnetic difference between the product and parent phase would change the Gibbs free energy of phase transformation. The volume fraction of BCC phase would increase slightly and the volume fraction of FCC and σ phases would decrease subtly, leading to a slightly higher saturation magnetization, ultimate compressive strength and plastic strain. Therefore, an excellent combination of saturation magnetization (∼89 emu/g), electrical resistivity (∼188 μΩ/cm), yield strength (∼1231 MPa), ultimate compressive strength (∼2708 MPa) and compressive plastic strain (∼26%) was achieved when applying 6 T magnetic field at heat treatment temperature of 1200 °C. This work provides a potential approach for future development of soft magnetic materials, with more preferable mechanical, electrical and magnetic properties.

Effect of Viscous Dissipation in Heat Transfer of MHD Flow of Micropolar Fluid Partial Slip Conditions: Dual Solutions and Stability Analysis

In this study, first-order slip effect with viscous dissipation and thermal radiation in micropolar fluid on a linear shrinking sheet is considered. Mathematical formulations of the governing equations of the problem have been derived by employing the fundamental laws of conservations which then converted into highly non-linear coupled partial differential equations (PDEs) of boundary layers. Linear transformations are employed to change PDEs into non-dimensional ordinary differential equations (ODEs). The solutions of the resultant ODEs have been obtained by using of numerical method which is presented in the form of shootlib package in MAPLE 2018. The results reveal that there is more than one solution depending upon the values of suction and material parameters. The ranges of dual solutions are S ≥ S c i , i = 0 , 1 , 2 and no solution is S < S c i where S c i is the critical values of S . Critical values have been obtained in the presence of dual solutions and the stability analysis is carried out to identify more stable solutions. Variations of numerous parameters have been also examined by giving tables and graphs. The numerical values have been obtained for the skin friction and local Nusselt number and presented graphically. Further, it is observed that the temperature and thickness of the thermal boundary layer increase when thermal radiation parameter is increased in both solutions. In addition, it is also noticed that the fluid velocity increases in the case of strong magnetic field effect in the second solution.

Thermomagnetic properties and Bjorken expansion of hot QCD matter in a strong magnetic field

In this work we have studied the effects of an external strong magnetic field on the thermodynamic and magnetic properties of a hot QCD matter and then explored these effects on the subsequent hydrodynamic expansion of the said matter once produced in the ultrarelativistic heavy ion collisions. For that purpose, we have computed the quark and gluon self-energies up to one loop in the strong magnetic field, using the HTL approximation with two hard scales - temperature and magnetic field, which in turn compute the effective propagators for quarks and gluons, respectively. Hence the quark and gluon contributions to the free energy are obtained from the respective propagators and finally derive the equation of state (EOS) by calculating the pressure and energy density. We have found that the speed of sound is enhanced due to the presence of strong magnetic field and this effect will be later exploited in the hydrodynamics. Thereafter the magnetic properties are studied from the free energy of the matter, where the magnetization is found to increase linearly with the magnetic field, thus hints the paramagnetic behavior. The temperature dependence of the magnetization is also studied, where the magnetization is found to increase slowly with the temperature. Finally, to see how a strong magnetic field could affect the hydrodynamic evolution, we have revisited the Bjorken boost-invariant picture with our paramagnetic EOS as an input in the equation of motion for the energy-momentum conservation. We have noticed that the energy density evolves faster than in the absence of strong magnetic field, i.e. cooling becomes faster, which could have implications on the heavy-ion phenomenology. As mentioned earlier, this observation can be understood by the enhancement of the speed of sound.

Magnetic field gradient inhibits Saccharomyces cerevisiae growth

The daily exposure of humans to artificial magnetic fields has inspired studies of their effects on biological systems. Different views are advocated by many research groups and few studies have clarified the role of magnetic field gradients in observed results. We investigated the effect of strong gradients and continuous magnetic fields in a cellular system. Colonies of Saccharomyces cerevisiae CCMB 355 were grown in solid and liquid media and exposed to the neodymium–iron–boron magnets. Notably, in solid medium, cells exposed to previously demagnetized NdFeB magnets or to the metals contained in magnets exhibited normal activities, but when exposed to the gradient, growth drastically fails near the magnet, even when the intensity of magnetism was near zero. Increasing the distance of the magnet to regions of weak magnetic field gradient caused decreased cellular malaise. When the magnet was removed, the cells were not capable of growing again, indicating that the gradient killed the exposed cells. In liquid medium, we observed a decrease in the absorbance values in the region of 560 nm when the substrate was directly permeated by a strong magnetic field gradient in comparison with a control without the magnet or with a magnet covered with a thin layer of silicone. This study helps to clarify the effect of the magnetic field gradient in biological systems.

Strong static magnetic field delayed the early development of zebrafish.

One of the major topics in magnetobiology is the biological effects of strong static magnetic field (SMF) on living organisms. However, there has been a paucity of the comprehensive study of the long-term effects of strong SMF on an animal's development. Here, we explored this question with zebrafish, an excellent model organism for developmental study. In our research, zebrafish eggs, just after fertilization, were exposed to a 9.0 T SMF for 24 h, the critical period of post-fertilization development from cleavage to segmentation. The effects of strong SMF exposure on the following developmental progress of zebrafish were studied until 6 days post-fertilization (dpf). Results showed that 9.0 T SMF exposure did not influence the survival or the general developmental scenario of zebrafish embryos. However, it slowed down the developmental pace of the whole animal, and the late developers would catch up with their control peers after the SMF was removed. We proposed a mechanical model and deduced that the development delaying effect was caused by the interference of SMF in microtubule and spindle positioning during mitosis, especially in early cleavages. Our research data provide insights into how strong SMF influences the developing organisms through basic physical interactions with intracellular macromolecules.

Magnetic-field-induced chain-like assemblies of the primary phase during non-equilibrium solidification of a Co-B eutectic alloy: Experiments and modeling

Systematic understanding on the morphology and magnetic alignment of the primary α-Co phase during non-equilibrium solidification of a Co-B eutectic alloy were carried out. Under an imposed magnetic field, a morphological alignment was found for the primary α-Co phase with its primary dendrite trunk or long axis paralleling to the direction of magnetic field. The primary α-Co phases are rod-like and spherical at relatively high undercooling, and the application of magnetic field is more conducive to obtain such kind of α-Co phases. The magnetic energy, magnetic torque and time required for rotation were analyzed theoretically to evaluate the magnetic alignment and alignment mechanisms. Subsequently, the dipolar forces between particles were calculated, based on which the phenomenon that the primary α-Co particles self-organize as chain-like stacking was described. The present research provides a better understanding of the strong magnetic field effects on non-equilibrium solidification and a potential technology of field-manipulation of ferromagnetic materials.

Electrical detection of ferromagnetic resonances with an organic light-emitting diode

Organic semiconductors show strong magnetic-field effects in transport and luminescence because of inherently spin-dependent recombination. We explore whether paramagnetic resonance features can be enhanced in a hybrid structure comprising a thin yttrium iron garnet (YIG) film, undergoing ferromagnetic resonance (FMR) and an organic light-emitting diode (OLED). We investigate the effect of radio-frequency (RF) driving of this hybrid structure in a magnetic field. Under these conditions, an indirect bolometric effect enables the detection of FMR driven in the YIG film in the DC resistance of the OLED. The increased RF power absorption of the YIG film under resonance gives rise to a heating of the magnetic film. Subsequent heat transfer to the OLED causes a change in transport characteristics of the device. Good agreement of this electrically detected signal is found with a direct measurement of the RF power absorption. Using temperature dependent measurements, the thermal nature of the resistance signal is confirmed.

Lightning and charge processes in brown dwarf and exoplanet atmospheres.

The study of the composition of brown dwarf atmospheres helped to understand their formation and evolution. Similarly, the study of exoplanet atmospheres is expected to constrain their formation and evolutionary states. We use results from three-dimensional simulations, kinetic cloud formation and kinetic ion-neutral chemistry to investigate ionization processes that will affect their atmosphere chemistry: the dayside of super-hot Jupiters is dominated by atomic hydrogen, and not H2O. Such planetary atmospheres exhibit a substantial degree of thermal ionization and clouds only form on the nightside where lightning leaves chemical tracers (e.g. HCN) for possibly long enough to be detectable. External radiation may cause exoplanets to be enshrouded in a shell of highly ionized, H3+-forming gas and a weather-driven aurora may emerge. Brown dwarfs enable us to study the role of electron beams for the emergence of an extrasolar, weather system-driven aurora-like chemistry, and the effect of strong magnetic fields on cold atmospheric gases. Electron beams trigger the formation of H3+ in the upper atmosphere of a brown dwarf (e.g. LSR-J1835), which may react with it to form hydronium, H3O+, as a longer lived chemical tracer. Brown dwarfs and super-hot gas giants may be excellent candidates to search for H3O+ as an H3+ product. This article is part of a discussion meeting issue 'Advances in hydrogen molecular ions: H3+, H5+ and beyond'.