Presence Of Strong Magnetic Field Research Articles

SKA sensitivity to sub-GeV dark matter decay: Synchrotron radio emissions in white dwarf magnetospheres

We investigate the potential of the Square Kilometre Array (SKA) in detecting synchrotron radiation emitted from the decay of sub-GeV dark matter (dark matter with masses below the GeV scale) in the presence of strong magnetic fields. As a concrete setup, we consider scenarios where the magnetosphere of a magnetic white dwarf overlaps with dense dark matter environments, such as those surrounding a primordial black hole. Our study reveals that the encounters of compact objects such as white dwarfs and black holes offer a promising avenue for upcoming radio telescopes to probe the properties of light dark matter, which has been less explored compared with more conventional heavier (masses above the GeV scale) dark matter. Published by the American Physical Society 2024

3D modeling of a double-driver ion source considering ion magnetization: an investigation of plasma symmetry modulation methods

A three-dimensional fluid model of a double-driver negative hydrogen ion source for China Fusion Engineering Test Reactor (CFETR) neutral beam injection is developed. In this model, the magnetic filter field is generated by 16 permanent magnets, which are surrounded by a soft iron. In order to accurately describe the transportation of charged species in the presence of strong magnetic field, both the electron magnetization and ion magnetization are taken into account, and the accuracy of the model has been proved by comparison with experimental data. By employing this model, the spatial distributions of the plasma parameters have been investigated, and three methods are proposed to optimize the symmetry at the bottom of the expansion region of a double-driver source. The results indicate that by adjusting the power of Driver I while keeping the power of Driver II constant, the symmetry of the electron density and negative hydrogen ion density could be improved. Furthermore, the inclusion of partition improves the symmetry of the electron temperature and density but has no impact on the regulation of the negative hydrogen ion density distribution. Finally, the application of magnetic shield can not only improve the symmetry of the electron density and negative hydrogen ion density, but also increase their densities at the bottom of the expansion region.

The high energy X-ray probe (HEX-P): a new window into neutron star accretion

Accreting neutron stars (NSs) represent a unique laboratory for probing the physics of accretion in the presence of strong magnetic fields (B ≳ 108 G). Additionally, the matter inside the NS itself exists in an ultra-dense, cold state that cannot be reproduced in Earth-based laboratories. Hence, observational studies of these objects are a way to probe the most extreme physical regimes. Here we present an overview of the field and discuss the most important outstanding problems related to NS accretion. We show how these open questions regarding accreting NSs in both low-mass and high-mass X-ray binary systems can be addressed with the High-Energy X-ray Probe (HEX-P) via simulated data. In particular, with the broad X-ray passband and improved sensitivity afforded by a low X-ray background, HEX-P will be able to 1) distinguish between competing continuum emission models; 2) provide tighter upper limits on NS radii via reflection modeling techniques that are independent and complementary to other existing methods; 3) constrain magnetic field geometry, plasma parameters, and accretion column emission patterns by characterizing fundamental and harmonic cyclotron lines and exploring their behavior with pulse phase; 4) directly measure the surface magnetic field strength of highly magnetized NSs at the lowest accretion luminosities; as well as 5) detect cyclotron line features in extragalactic sources and probe their dependence on luminosity in the super-Eddington regime in order to distinguish between geometrical evolution and accretion-induced decay of the magnetic field. In these ways HEX-P will provide an essential new tool for exploring the physics of NSs, their magnetic fields, and the physics of extreme accretion.

Unitary coupled-cluster for quantum computation of molecular properties in a strong magnetic field.

In truncated coupled-cluster (CC) theories, non-variational and/or generally complex ground-state energies can occur. This is due to the non-Hermitian nature of the similarity transformed Hamiltonian matrix in combination with CC truncation. For chemical problems that deal with real-valued Hamiltonian matrices, complex CC energies rarely occur. However, for complex-valued Hamiltonian matrices, such as those that arise in the presence of strong magnetic fields, complex CC energies can be regularly observed unless certain symmetry conditions are fulfilled. Therefore, in the presence of magnetic fields, it is desirable to pursue CC methods that are guaranteed to give upper-bound, real-valued energies. In this work, we present the first application of unitary CC to chemical systems in a strong magnetic field. This is achieved utilizing the variational quantum eigensolver algorithm applied to the unitary coupled-cluster singles and doubles (UCCSD) method. We benchmark the method on the H2 molecule in a strong magnetic field and then calculate UCCSD energies for the H4 molecule as a function of both geometry and field angle. We show that while standard CCSD can yield generally complex energies that are not an upper-bound to the true energy, UCCSD always results in variational and real-valued energies. We also show that the imaginary components of the CCSD energy are largest in the strongly correlated region. Last, the UCCSD calculations capture a large percentage of the correlation energy.

A way of determination of axion mass with quantum Hall effect

Axion dark matter is converted to electromagnetic radiations in the presence of strong magnetic field. The radiations possibly give rise to non trivial phenomena in condensed matter physics. Especially, we discuss that saturation of plateau-plateau transition width observed at low temperature in integer quantum Hall effect is caused by the axion. The radiations from axions are inevitably present in the experiment. Although the radiations generated by axion are extremely weak, Hall conductivity jumps up to next plateau even if only a single electron occupies an extended state; a localized electron is transited to the extended state by absorbing the radiation. According to our analysis, previous experiment [33] of the saturation in detail suggests that the axion mass is in the range 10−5eV∼10−6 eV. We propose a way of the determination of the axion mass by imposing microwaves on Hall bar and also a way of the confirmation that the axion really causes the saturation of the width.

Thermal Contact Resistance at Cryogenic Temperatures in the Presence of Strong Magnetic Fields

A physical model of a mechanical thermal switch at cryogenic temperatures is studied. In the model, heat is transferred due to contact heat conduction in a detachable contact pair of two copper cylinders. A mechanical thermal switch is developed using a cryomagnetic system with a 10-T superconducting solenoid, and the values of thermal contact conductance are determined in a temperature interval of 10–160 K, including values at a magnetic field of 5 T. In an experimental temperature interval of 60–80 K, close to the phase transition of the DyAl2 and GdNi2 compounds, the thermal contact conductance is 2300–3300 W/(m2 K). The effect of magnetic field of up to 5 T on thermal contact resistance is experimentally determined under vacuum conditions

Thermal Contact Resistance at Cryogenic Temperatures in the Presence of Strong Magnetic Fields

Thermal Contact Resistance at Cryogenic Temperatures in the Presence of Strong Magnetic Fields

(Anti)kaon condensation in strongly magnetized dense matter

Recent observations of several massive pulsars, with masses near and above $2~M_\odot$, point towards the existence of matter at very high densities, compared to normal matter that we are familiar with in our terrestrial world. This leads to the possibility of appearance of exotic degrees of freedom other than nucleons inside the core of the neutrons stars (NS). Another significant property of NSs is the presence of high surface magnetic field, with highest range of the order of $\sim~10^{16}$ G. We study the properties of highly dense matter with the possibility of appearance of heavier strange and non-strange baryons, and kaons in presence of strong magnetic field. We find that the presence of a strong magnetic field stiffens the matter at high density, delaying the kaon appearance and, hence, increasing the maximum attainable mass of NS family.

Nonlinearity and Parametric Amplification of Superconducting Nanowire Resonators in Magnetic Field

Nonlinear superconducting devices, typically based on Josephson Junction (JJ) nonlinearities, are the basis for superconducting quantum electronics, enabling, e.g., the formation of isolated two-level superconducting qubits and amplifiers. While emerging spin, hybrid spin/superconducting (including Majorana), and nano-magneto-optical quantum systems could benefit tremendously from superconducting nonlinearities, the presence of strong magnetic fields in these systems are incompatible with conventional JJ devices, which are highly sensitive to applied magnetic fields. One potential solution is the use of kinetic inductance (KI) nonlinearity. To date, only linear kinetic inductance (KI) devices have been shown to operate in high magnetic fields, while nonlinear KI device operation in high magnetic fields has received virtually no attention. Here, we study the nonlinearity of superconducting nanowire (NW) KI resonators and their performance as parametric amplifiers for in-plane magnetic fields. We study the Kerr coefficients of NW KI resonators made from 10 nm-thin NbTiN films with characteristic impedance up to 3 k$\Omega$, and demonstrate both nondegenerate and degenerate parametric amplification, at magnetic fields up to 2 T, for the first time. We find that narrow KI resonators of width 0.1 $\mu$m are robust, in terms of gain, dynamic range and noise, to magnetic fields up to $\sim$2 T, while wider KI resonators of width 1 $\mu$m suffer significant suppression in the gain around at fields well below 2 T. Around 8 dB deamplification is observed for coherent states for a 0.1 $\mu$m KI resonator, implying the capability of noise squeezing. These results open a new pathway to developing nonlinear quantum devices that operate in or generate high magnetic fields such as spin, hybrid spin/superconducting, and magneto-opto-mechanical devices.

Resonant Contributions to Oscillatory Phenomena under Conditions of Magnetic Breakdown during Reconstructions of Electron Dynamics on the Fermi Surface

We consider here special closed electron trajectories that arise during reconstructions of electron dynamics on the Fermi surface in the presence of strong magnetic fields, as well as the phenomenon of intraband magnetic breakdown that occurs on such trajectories. We consider cases where the electronic spectrum arising in such a situation corresponds to the resonant contribution to quantum oscillations. In the paper, all cases where this occurs are singled out, and the possible influence of the appearance of the Berry phase and other effects on the described phenomena is also considered.

InAs/MoRe Hybrid Semiconductor/Superconductor Nanowire Devices

Implementing superconductors capable of proximity-inducing a large energy gap in semiconductors in the presence of strong magnetic fields is a major goal toward applications of semiconductor/superconductor hybrid materials in future quantum information technologies. Here, we study the performance of devices consisting of InAs nanowires in electrical contact with molybdenum-rhenium (MoRe) superconducting alloys. The MoRe thin films exhibit transition temperatures of ∼10 K and critical fields exceeding 6 T. Normal/superconductor devices enabled tunnel spectroscopy of the corresponding induced superconductivity, which was maintained up to ∼10 K, and MoRe-based Josephson devices exhibited supercurrents and multiple Andreev reflections. We determine an induced superconducting gap lower than expected from the transition temperature and observe gap softening at finite magnetic field. These may be common features for hybrids based on large-gap, type II superconductors. The results encourage further development of MoRe-based hybrids.

MHD stagnation point flow of a water-based copper nanofluid past a flat plate with solar radiation effect

Due to many biological and technical applications, including microelectronics, heat exchangers, cancer therapy, process industries, solar collectors and power production, researchers have been more interested in the mechanism of heat transfer involving nanomaterials. A contemporary method to increase the thermal conductivity of various cooling fluids is the use of nanomaterials. Many researches suggest that the thermal conductivity of nanoliquids; solid nanoparticles combined with a base fluid, is expressively greater than that of conventional fluids. This work presents the theoretical investigation of magnetohydrodynamic stagnation point flow of non-Newtonian nanofluid flow past flat plate. The applications of solar radiation towards water-based copper nanoparticles are highlighted in this study. The system of PDEs is transmuted into the system of ODEs by mean of suitable similarity variable. Analytical solution of the present analysis has been performed with the help of HAM technique. The impacts of physical factors on the flow profiles, skin friction coefficient, heat, and mass transfer rates are calculated. It is significant to note that the default concentration is weighted by 4% throughout this analysis. Also in this analysis, we examined the temperature and heat transfer rate for the presence and absence of solar radiation. It is found that the greater nanoparticles volume fraction of the water-based copper nanoparticles has accelerated the flow profiles for the absence of magnetic field. However, for the presence of strong magnetic field, the velocity, and temperature of the water-based copper nanoparticles have significantly reduced. Due to the incidence of Lorentz force, the velocity of the water-based copper nanoparticles has deteriorated, while the temperature profile has augmented. It is found that the solar radiation has always dominant impression on temperature of the water based copper nanoparticles.

Phase transitions and latent heat in magnetized matter

Based on the assumption that the QCD phase diagram gives a realistic picture of hadronic and quark matter under different regimes, it is possible to claim that a quark core may be present inside compact objects commonly named hybrid neutron stars or even that a pure strange star may exist. In this work we explore how the phase transition is modified by the presence of strong magnetic fields and how it is impacted by parameters of the quark phase, for which we use the MIT-model with vector interactions. The phase transition is assumed to conserve flavor when hadrons turn into deconfined quarks. The hadronic equation of state is calculated with the NL3$\omega\rho^\ast$ parametrization of quantum hadrodynamics. We find that the magnetic field slightly reduces the pressure and chemical potential of the phase transition and the latent heat, the latter being very model dependent.

Broadband spectro-temporal study on blazar TXS 1700+685

ABSTRACT We attempt to present a multiwavelength variability and correlation study as well as detailed multiwaveband spectral characteristics of the May 2021 gamma-ray flare of the blazar source TXS 1700+685. The multiwavelength observation from Fermi-LAT, Swift-XRT/UVOT as well as radio archival data are used for our spectro-temporal investigation. We estimate the variability time-scale of the source from the flux doubling time in different flaring region detected in Fermi-LAT observation and the shortest variability time is used to put a constraint on the minimum Doppler factor and on the size of the emission region. We have detected a statistically significant quasi-periodic oscillation feature at ∼17 d. The broad-band emission is satisfactorily represented during its flaring state with a leptonic synchrotron and inverse Compton component. From the broad-band spectral modelling, we observe the external Comptonization of the seed photons originating in the broad-line region to be dominant compared to the dusty torus. The equipartition value implies the energy density of the magnetic field in the jet comoving frame is weak. In order to produce the high-energy hump, we need the injection of a large population of high-energy electrons and/or the presence of strong magnetic field; and we observe the later component to be subdominant in our case. The gamma-ray spectral energy distribution shows the flat rising and steep falling profile, as well as the break or spectral curvature at ∼1 GeV, which has been seen for other flat-spectrum radio quasar sources before.

Melting of Quarkonia in strong magnetic field

In this paper, spectra of the quarkonium states has been studied using the conditions temperature, chemical potential and the magnetic field. Here our main focus is to study the effect of strong magnetic field on the quarkonium properties. The binding energies and the dissociation temperature for the ground and the first excited states of the charmonium and bottomonium in the presence of strong magnetic field at chemical potential μ = 500 MeV has been studied. Here we use quasiparticle(QP) Debye mass depending upon temperature, magnetic field and chemical potential obtained from the quasiparticle approach. The Debye mass strongly increases at different values of temperature and magnetic field. The binding energy decreases with increase in the temperature at different magnetic field eB=0.3, 0.5, and 0.7 GeV2 and also decreases with magnetic field at different at T=200,300 and 400 MeV for the J/ψ, Ψ’, ϒ, and ϒ’ states of the quarkonia. The dissociation temperature of the quarkonium states falls with the increasing values of the magnetic field at critical temperature Tc =197 MeV.

MRI-LINAC dosimetry approach by Monte Carlo codes coupling charged particle radiation transport with strong magnetic fields

This study investigates the dosimetric effects due to the strong magnetic fields in the MRI guided radiotherapy. FLUKA and PENELOPE Monte Carlo codes were used to study the deflection of the electron trajectories, while evaluating dosimetric effects, considering both simplified arrangements and complex realistic clinical applications setups. Simulation codes proved to be suitable, and comparisons with analytic approaches were satisfactory, thus remarking non-negligible dosimetry effects as a consequence of the presence of strong magnetic fields.

ESTUDIO ANALÍTICO Y POR SIMULACIÓN MONTE CARLO DE LA INFLUENCIA DECAMPOS MAGNÉTICOS INTENSOS EN LA TRAYECTORIA DE ELECTRONES CONENERGÍAS TÍPICAS DE RADIOTERAPIA MRI-LINAC

Both analytical and numerical methods have proven to be suitable for describing radiation transport and interactions. The standard Boltzmann formalism derived from statistical mechanics requires to be specifically re-formulated to account for the interactions with external electromagnetic fields. Verifying the proper implementation of the external electromagnetic field coupling in Monte Carlo simulation codes is a key issue to confirm the feasibility of using such a tool to describe complex applications like image-guided radiotherapy based on integrating magnetic resonance scanner to the radiant field of ionizing radiation along with the subsequent dosimetric effects. The present work reports on the feasibility and reliability of the Monte Carlo FLUKA and PENELOPE main codes to assess electron trajectory in presence of strong magnetic fields. The obtained results confirm the ability of FLUKA and Penelope to model the alterations in the electron trajectories due to external magnetic field effects, also demonstrating an excellent agreement between both codes and with the theoretical-analytical model.

X-Ray Emission from Candidate Stellar Merger Remnant TYC 2597-735-1 and Its Blue Ring Nebula

Abstract Tight binary or multiple-star systems can interact through mass transfer and follow vastly different evolutionary pathways than single stars. The star TYC 2597-735-1 is a candidate for a recent stellar merger remnant resulting from a coalescence of a low-mass companion with a primary star a few thousand years ago. This violent event is evident in a conical outflow (“Blue Ring Nebula”) emitting in UV light and surrounded by leading shock filaments observed in Hα and UV emission. From Chandra data, we report the detection of X-ray emission from the location of TYC 2597-735-1 with a luminosity log ( L X / L bol ) = − 5.5 . Together with a previously reported period of ~14 days, this indicates ongoing stellar activity and the presence of strong magnetic fields on TYC 2597-735-1. Supported by stellar evolution models of merger remnants, we interpret the inferred stellar magnetic field as dynamo action associated with a newly formed convection zone in the atmosphere of TYC 2597-735-1, though internal shocks at the base of an accretion-powered jet cannot be ruled out. We speculate that this object will evolve into an FK Com–type source, i.e., a class of rapidly spinning magnetically active stars for which a merger origin has been proposed but for which no relic accretion or large-scale nebula remains visible. We also detect likely X-ray emission from two small regions close to the outer shock fronts in the Blue Ring Nebula, which may arise from inhomogeneities either in the circumstellar medium or in the mass and velocity distribution in the merger-driven outflow.

Pasta phases in neutron stars under strong magnetic fields

In the present work, we consider nuclear matter in the innermost crust of neutron stars under the presence of a strong magnetic field within the framework of a relativistic mean-field description. Two models with a different slope of the symmetry energy are considered in order to discuss the density dependence of the equation of state on the crust structure. The nonhomogeneous matter in $\ensuremath{\beta}$ equilibrium is described within the coexisting phases method, and the effect of including the anomalous magnetic moment is discussed. Five different geometries for the pasta structures are considered. It is shown that strong magnetic fields cause an extension of the inner crust of the neutron stars, with the occurrence of a series of disconnected nonhomogeneous matter regions above the one existing for a null magnetic field. Moreover, we observed that in these disconnected regions, for some values of the magnetic field, all five different cluster geometrical shapes occur, and the gas density is close to the cluster density. Also, the pressure at the neutron star crust-core transition is much larger than the pressure obtained for a zero magnetic field. Another noticeable effect of the presence of strong magnetic fields is the increase of the proton fraction, favoring the appearance of protons in the gas background.

Intensity and Polarization Characteristics of Extended Neutron Star Surface Regions

Abstract The surfaces of neutron stars are sources of strongly polarized soft X-rays due to the presence of strong magnetic fields. Radiative transfer mediated by electron scattering and free–free absorption is central to defining local surface anisotropy and polarization signatures. Scattering transport is strongly influenced by the complicated interplay between linear and circular polarizations. This complexity has been captured in a sophisticated magnetic Thomson scattering simulation we recently developed to model the outer layers of fully ionized atmospheres in such compact objects, heretofore focusing on case studies of localized surface regions. Yet, the interpretation of observed intensity pulse profiles and their efficacy in constraining key neutron star geometry parameters is critically dependent upon adding up emission from extended surface regions. In this paper, intensity, anisotropy, and polarization characteristics from such extended atmospheres, spanning considerable ranges of magnetic colatitudes, are determined using our transport simulation. These constitute a convolution of varied properties of Stokes parameter information at disparate surface locales with different magnetic field strengths and directions relative to the local zenith. Our analysis includes full general relativistic propagation of light from the surface to an observer at infinity. The array of pulse profiles for intensity and polarization presented highlights how powerful probes of stellar geometry are possible. Significant phase-resolved polarization degrees in the range of 10%–60% are realized when summing over a variety of surface field directions. These results provide an important background for observations to be acquired by NASA’s new Imaging X-ray Polarimetry Explorer X-ray polarimetry mission.