Polar Magnetic Field Research Articles

An approach for measurement of the magnetic field near the surface of plasma-facing components in tokamak by laser induced breakdown spectroscopy based on Zeeman effect

Laser-induced breakdown spectroscopy (LIBS) has been demonstrated to diagnose the surface element distribution of plasma-facing components (PFCS) in fusion devices. However, the magnetic field intensity and polarity near the wall surface change frequently and cannot be measured in real time, which will affect the analytical accuracy of LIBS results. The determination of the strength and polarity direction of the magnetic field near the surface will be conducive to the quantitative analysis of LIBS and provide valuable information for the distribution of the magnetic field near the surface of PFCs. In this work, the effects of magnetic fields on the characteristics of laser-induced Mo plasma, such as the ablation depth and mass, the spatio-temporal evolution behavior of spectrum and the plasma parameters, were first systematically investigated. The different phenomenon of continuum radiation, Mo I line and Mo II line under the magnetic field were mutually verified by optical emission spectroscopy and fast plasma imaging methods. Meanwhile, an approach for measurement of the magnetic field intensity and polarity near the surface of PFCS by LIBS method has been proposed and investigated. When the magnetic field polarity is changed, the spatial distribution profile of Mo spectrum will drift in the opposite direction affected by of the Lorentz force, which realizes the measurement of magnetic field polarity. Moreover, the splitting distance of Mo I line caused by Zeeman effect with the variable magnetic fields were preliminarily calculated. The experimental values of splitting distance agree well with the theoretical values that calculated by the known magnetic field strength. These results confirm the feasibility of measuring the magnetic field intensity and polarity of PFCs surface by LIBS approach.

Limitations and Biases in the Retrieval of the Polar Magnetic Field. I. The Role of the Magnetic Filling Factor in Milne–Eddington Inversions of Simulated Hinode/SP Data

We study the extent to which Milne–Eddington inversions are able to retrieve and characterize the magnetic landscape of the solar poles from observations by the spectropolarimeter on board Hinode. In particular, we evaluate whether a variable magnetic filling factor is an adequate modeling technique for retrieving the intrinsic magnetic properties from every pixel in the polar field of view. We first generate synthetic spectra emerging from a numerical simulation of a “plage” region at an inclined line of sight of 65°, and degrade the data to emulate real observations. Then, we invert the synthetic spectra with two Milne–Eddington inversion codes that feature different treatments of the magnetic filling factor, and relate the retrieved magnetic quantities back to their original values in the simulation cube. We find that, while the apparent retrieved magnetic properties map the spatially degraded simulation well, the intrinsic magnetic quantities bear little relation to the magnetic field at the native resolution of the simulation. We discuss the systematic biases caused by line-of-sight foreshortening, spatial degradation, photon noise, and modeling assumptions embedded in the inversion algorithm.

Zeeman Doppler imaging ofξBoo A and B

Aims.We present a magnetic-field surface map for both stellar components of the young visual binaryξBoo AB (A: G8V, B: K5V).Methods.We employed high-resolution Stokes-Vspectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT). We inverted StokesVline profiles with ouriMAP software and compared them with previous inversions. We employed an iterative regularization scheme without the need for a penalty function and incorporated a three-component description of the surface magnetic-field vector. The spectral resolution of our data is 130 000 (0.040–0.055 Å) and we obtain a signal-to-noise ratio (S/N) of up to 3000 per pixel depending on wavelength. We used a singular-value decomposition (SVD) of a total of 1811 spectral lines to average Stokes-Vprofiles. Our mapping is accompanied by a residual bootstrap error analysis.Results.We constructed magnetic flux densities of the radial field component forξBoo A andξBoo B of up to plus or −115±5 G and 55±3 G, respectively. The magnetic morphology ofξBoo A is characterized by a very high latitude, nearly polar spot of negative polarity and three low-to-mid-latitude spots of positive polarity, while that ofξBoo B is characterized by four low-to-mid-latitude spots of mixed polarity. No polar magnetic field is reconstructed for the coolerξBoo B star. Both our maps are dominated by the radial field component, containing 86% and 89% of the magnetic energy ofξBoo A and B, respectively. We find only weak azimuthal and meridional field densities on both stars (plus or −15–30 G), about a factor two weaker than what was seen previously forξBoo A. The phase averaged longitudinal field component and dispersion is +4.5±1.5 G for ξ Boo A and −5.0±3.0 G forξBoo B.

Which Component of Solar Magnetic Field Drives the Evolution of Interplanetary Magnetic Field over the Solar Cycle?

The solar magnetic structure changes over the solar cycle. It has a dipole structure during solar minimum, where the open flux extends mainly from the polar regions into the interplanetary space. During maximum, a complex structure is formed with low-latitude active regions and weakened polar fields, resulting in spread open field regions. However, the components of the solar magnetic field that are responsible for long-term variations in the interplanetary magnetic field (IMF) are not clear, and the IMF strength estimated based on the solar magnetic field is known to be underestimated by a factor of 3–4 against the actual in situ observations (the open flux problem). To this end, we decomposed the coronal magnetic field into the components of the spherical harmonic function of degree and order (ℓ, m) using the potential field source surface model with synoptic maps from SDO/HMI for 2010–2021. As a result, we found that the IMF rapidly increased in 2014 December (7 months after the solar maximum), which coincided with the increase in the equatorial dipole, (ℓ, m) = (1, ±1), corresponding to the diffusion of active regions toward the poles and in the longitudinal direction. The IMF gradually decreased until 2019 December (solar minimum) and its variation corresponded to that of the nondipole component ℓ ≥ 2. Our results suggest that the understanding of the open flux problem may be improved by focusing on the equatorial dipole and the nondipole component and that the influence of the polar magnetic field is less significant.

General-relativistic neutrino-radiation magnetohydrodynamics simulation of seconds-long black hole-neutron star mergers: Dependence on the initial magnetic field strength, configuration, and neutron-star equation of state

As a follow-up study of our previous work [Phys. Rev. D 106, 023008 (2022)], numerical-relativity simulations for seconds-long black hole-neutron star mergers are performed for a variety of setups. Irrespective of the initial and symmetry conditions, we find qualitatively universal evolution processes: The dynamical mass ejection takes place together with a massive accretion disk formation after the neutron star is tidally disrupted; subsequently, the magnetic field in the accretion disk is amplified by the magnetic winding, Kelvin-Helmholtz instability, and magnetorotational instability, which establish a turbulent state inducing the dynamo and angular momentum transport; the postmerger mass ejection by the effective viscous processes stemming from the magnetohydrodynamics turbulence sets in at $\ensuremath{\sim}300--500\text{ }\text{ }\mathrm{ms}$ after the merger and continues for several hundred ms; a magnetosphere near the black-hole spin axis is developed and the collimated strong Poynting flux is generated with its lifetime of $\ensuremath{\sim}0.5--2\text{ }\text{ }\mathrm{s}$. We have newly found that the model of no equatorial-plane symmetry shows the reverse of the magnetic-field polarity in the magnetosphere, which is caused by the dynamo associated with the magnetorotational instability in the accretion disk. The model with initially toroidal fields shows the tilt of the disk and magnetosphere in the late postmerger stage because of the anisotropic postmerger mass ejection. These effects could terminate the strong Poynting-luminosity stage within the timescale of $\ensuremath{\sim}0.5--2\text{ }\text{ }\mathrm{s}$.

Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station.

We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical "drift model" of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.

Unveiling a hidden multiferroic state under magnetic fields in BaHoFeO4

In this paper, we report field-induced ferroelectricity in ${\mathrm{BaHoFeO}}_{4}$ in a narrow range of applied magnetic fields ($1.5\phantom{\rule{4.pt}{0ex}}\text{T}\ensuremath{\le}H\ensuremath{\le}5\phantom{\rule{4.pt}{0ex}}\text{T}$). Magnetization measurements reveal three magnetic anomalies, the first one at ${T}_{N}^{\text{Fe}}\ensuremath{\sim}52.8$ K, the second one at ${T}_{{N}_{2}}\ensuremath{\sim}36.4$ K, and the third one at ${T}_{N}^{\text{Ho}}\ensuremath{\sim}6.8$ K, corresponding to the antiferromagnetic ordering of ${\mathrm{Fe}}^{3+}$, a possible spin structure change of ${\mathrm{Fe}}^{3+}$, and the antiferromagnetic ordering of ${\mathrm{Ho}}^{3+}$ sublattices, respectively. Surprisingly, the heat capacity data did not show any anomaly at ${T}_{N}^{\text{Fe}}$ but exhibited a broad maximum at ${T}_{N}^{\text{Ho}}$. Below 40 K, isothermal magnetization measurements indicate a metamagnetic transition at 1.5 T. The temperature-dependent dielectric measurements performed below 1 T reveal two anomalies, around 6 and 36 K, corresponding to ${\mathrm{Ho}}^{3+}$ ordering and a possible change in the magnetic phase of the Fe sublattice. These anomalies disappear at higher magnetic fields, and a different dielectric anomaly appears above the metamagnetic transition with a broad asymmetric peak around 13 K (${T}_{P}$), which shifts to higher temperatures, reaches a maximum under 2 T, and then is suppressed further on increasing the magnetic field up to 9 T. A switchable electric polarization appears below 25 K and above the metamagnetic transition field ($H\ensuremath{\ge}1.5$ T). Intriguingly, the polarization disappears above 5 T. The presence of electric polarization in intermediate magnetic fields and its strong magnetic field dependence are interesting and make this material unique.

Quark condensate and magnetic moment in a strong magnetic field

This paper studies the quark condensate, magnetic moment, magnetic polarization, and magnetic susceptibility in a strong external magnetic field by employing the Dyson–Schwinger equations (DSE). The results show these physical quantities as functions of the magnetic field. We note that the quark’s spin polarizations are approximately proportional to the magnetic field magnitude. For comparison, we investigate the magnetic moments and susceptibility of the nucleon in the constituent quark model framework and demonstrate that both these quantities increase as the magnetic field rises.

Ripples and Rush-to-the-Poles in the Photospheric Magnetic Field

The distribution of magnetic fields of positive and negative polarities over the surface of the Sun was studied on the basis of synoptic maps presented by the NSO/Kitt Peak (1978-2016). To emphasize the contribution of weak fields the following transformation of synoptic maps was made: for each synoptic map only magnetic fields with modulus less than 5G ($|B|\leq 5$G) were left unchanged while larger or smaller fields were replaced by the corresponding threshold values +5G or $-5$G. Cyclic variations of the magnetic field polarity have been observed associated with two types of magnetic field flows in the photosphere. Rush-to-the-Poles (RTTP) appear near the maximum of solar activity and have the same sign as the following sunspots. The lifetime of RTTP is $\sim 3$ yrs, during which time they drift from latitudes $30^\circ$-$40^\circ$ to the pole, causing the polarity change of the Sun's polar field. Our aim is the study of another type of variations which has the form of series of flows with individual flows of 0.5-1 yr with alternating polarity. These flows called ripples are located in time between two RTTP and drift from the equator to the latitudes of $~50^\circ$. The period of variation of ripples was shown to be 1.1 yr for the northern hemisphere and 1.3 yr for the southern hemisphere. It was found that the amplitude of variation was higher for the time intervals where the polar field had a positive sign. Within the same flow, fields of positive and negative signs developed in anti-phase. Two types of flows - RTTP and ripples - together formed a unique structure which had close connection to the magnetic solar cycle.

Geophysical research of underground hydraulic structures, old Glubochinsky water tunnel case study

Research objective is to study the features of geophysical fields and parameters in the area of the artificial underground water tunnel and estimate the capabilities of geophysical methods of identifying hidden underground industrial facilities. Methods of research. Measurements of self-potential signals (SP) were carried out using nonpolarizing electrodes and an electrical exploration receiver. The magnetic exploration was carried out by a proton magnetometer. Electrotomography was carried out using multielectrode electrical survey equipment with a Schlumberger symmetrical scheme of surveys. The microseismic background was recorded using an autonomous seismic station. The georadar survey was carried out using the SIR-3000 ground penetrating radar and antennas with the frequencies of 100 MHz and 270 MHz. Results. Based on the survey results, graphs of magnetic and self-potential fields, electrotomographic and microseismic sections, and radarogram were built on the research profile. The research has shown different levels of the magnetic field and the SP in the area of volcanic rocks and dikes of gabbro-dolerites occurrence. A significant increase in microseismic noise was observed with an increase in the weathering crust thickness. A local decrease in the SP potential, abnormally high values of specific electrical resistivity and intensive reflections of radio waves from the tunnel top were recorded above the underground water tunnel. Conclusions. Qualitative and quantitative geophysical characteristics were obtained in the area of the old underground water tunnel. The research showed different levels of the magnetic field and spontaneous polarization potentials in the occurrence area of rocks of different composition. A significant increase in microseismic noise was recorded with an increase in the weathering crust thickness. Geophysical signs of the boundaries between geological structures and artificial underground objects are revealed. The exact position and depth of the old underground tunnel of Glubochinsky hydraulic structures was determined.

Saturated absorption spectrum of cesium micrometric-thin cell with suppressed crossover spectral lines

Micrometric-thin cells (MCs) with alkali vapor atoms have been valuable for research and applications of hyperfine Zeeman splitting and atomic magnetometers under strong magnetic fields. We theoretically and experimentally study the saturated absorption spectra using a 100-μm cesium MC, where the pump and probe beams are linearly polarized with mutually perpendicular polarizations, and the magnetic field is along the pump beam. Because of the distinctive thin chamber of the MC, crossover spectral lines in saturated absorption spectra are largely suppressed leading to clear splittings of hyperfine Zeeman transitions in experiments, and the effect of spatial magnetic field gradient is expected to be reduced. A calculation method is proposed to achieve good agreements between theoretical calculations and experimental results. This method successfully explains the suppression of crossover lines in MCs, as well as the effects of magnetic field direction, propagation and polarization directions of the pump/probe beam on saturated absorption spectrum. The saturated absorption spectrum with suppressed crossover lines is used for laser frequency stabilization, which may provide the potential value of MCs for high spatial resolution strong-field magnetometry with high sensitivity.

Polar Photospheric Magnetic Field Evolution and Global Flux Transport

Polar Photospheric Magnetic Field Evolution and Global Flux Transport

Study of the Green Coronal Line with Altitude from Out-of-Eclipse Observations during Solar Cycle 24

The results of studies of the coronal emission line λ = 5303 Å (Fe XIV) for the period of solar cycle 24 are presented. The spectral data were obtained with an out-of-eclipse Lyot coronagraph at the Mountain Astronomical Station of the Pulkovo Observatory, Russian Academy of Sciences (near Kislovodsk). As a result of processing of out-of-eclipse observations, a database of three types of daily coronal maps of green line intensity I5303 was created with a height distribution h from 1R☉ to 1.38R☉ (R☉ is the radius of the Sun). Irregularities along the λ = 5303 Å line were found and identified, which were associated with the configuration of magnetic fields in the solar corona above active regions. The length of the green line from the position angle of the Sun was calculated. We have shown that the time distribution of the line length in the polar regions has two maxima, which coincide with the times of the reversal of the polar magnetic field on the Sun. The maximum values of the average length of the coronal line along the entire limb occur in 2012–2014. For different phases (the rise, the period of maximum, the decline, and the minimum solar activity) of this solar cycle and for different regions of solar activity, dependences of the height variations of the I5303 values were plotted and studied. The regression equations for these fitting curves are presented. The variation in I5303 with height for the polar regions is most likely determined by a logarithmic function, and the approximating trend curves for the remaining latitudinal zones are determined by a third-order power function.

Prediction for the amplitude and second maximum of Solar Cycle 25 and a comparison of the predictions based on strength of polar magnetic field and low-latitude sunspot area

ABSTRACTThe maximum of a solar cycle contains two or more peaks, known as Gnevyshev peaks. Studies of this property of solar cycles may help in better understanding the solar dynamo mechanism. We analysed the 13-month smoothed monthly mean Version-2 international sunspot number (SN) during the period 1874–2017 and found that there exists a good correlation between the amplitude (value of the main and highest peak) and the value of the second maximum (value of the second highest peak) during the maximum of a solar cycle. Using this relationship and the earlier predicted value 86 ± 18 (92 ± 11) of the amplitude of Solar Cycle 25, here we predict a value 73 ± 15 (79 ± 15) for the second maximum of Solar Cycle 25. The ratio of the predicted second maximum to the amplitude is found to be 0.85, almost the same as that of Solar Cycle 24. The least-square cosine fits to the values of the peaks that occurred first and second during the maxima of Solar Cycles 12–24 suggest that in Solar Cycle 25 the second maximum would occur before the main maximum, the same as in Solar Cycle 24. However, these fits suggest ≈106 and ≈119 for the second maximum and the amplitude of Solar Cycle 25, respectively. Earlier, we analysed the combined Greenwich and Debrecen sunspot-group data during 1874–2017 and predicted the amplitude of Solar Cycle 25 from the activity just after the maximum of Solar Cycle 24 in the equatorial latitudes of the Sun’s Southern hemisphere. Here, from the hindsight of the results we found the earlier prediction is reasonably reliable. We analysed the polar-fields data measured in Wilcox Observatory during Solar Cycles 20–24 and obtained a value 125 ± 7 for the amplitude of Solar Cycle 25. This is slightly larger – whereas the value ≈86 (≈92) predicted from the activity in the equatorial latitudes is slightly smaller – than the observed amplitude of Solar Cycle 24. This difference is discussed briefly.

Using Machine Learning to link black hole accretion flows with spatially resolved polarimetric observables

ABSTRACT We introduce a new library of 535 194 model images of the supermassive black holes and Event Horizon Telescope (EHT) targets Sgr A* and M87*, computed by performing general relativistic radiative transfer calculations on general relativistic magnetohydrodynamics simulations. Then to infer underlying black hole and accretion flow parameters (spin, inclination, ion-to-electron temperature ratio, and magnetic field polarity), we train a random forest machine learning model on various hand-picked polarimetric observables computed from each image. Our random forest is capable of making meaningful predictions of spin, inclination, and the ion-to-electron temperature ratio, but has more difficulty inferring magnetic field polarity. To disentangle how physical parameters are encoded in different observables, we apply two different metrics to rank the importance of each observable at inferring each physical parameter. Details of the spatially resolved linear polarization morphology stand out as important discriminators between models. Bearing in mind the theoretical limitations and incompleteness of our image library, for the real M87* data, our machinery favours high-spin retrograde models with large ion-to-electron temperature ratios. Due to the time-variable nature of these targets, repeated polarimetric imaging will further improve model inference as the EHT and next-generation (EHT) continue to develop and monitor their targets.

Tensor CSRMT System with Horizontal Electrical Dipole Sources and Prospects of Its Application in Arctic Permafrost Regions

When studying horizontally-inhomogeneous media, it is necessary to apply tensor modifications of electromagnetic soundings. Use of tensor measurements is of particular relevance in near-surface electrical prospecting because the upper part of the geological section is usually more heterogeneous than the deep strata. In the Enviro-MT system designed for the controlled-source radiomagnetotelluric (CSRMT) sounding method, two mutually perpendicular horizontal magnetic dipoles (two vertical loops) are used for tensor measurements. We propose a variant of the CSRMT method with two horizontal electrical dipole sources (two transmitter lines). The advantage of such sources is an extended frequency range of 1–1000 kHz in comparison with 1–12 kHz of the Enviro-MT system, greater operational distance (up to 3–4 km compared to 600–800 m), and the ability to measure the signal at the fundamental frequency and its subharmonics. To implement tensor measurements with the equipment of the CSRMT method described in the paper, a technique of creating a time-varying polarization of the electromagnetic field (rotating field) has been developed based on the use of two transmitters with slightly different current frequencies and two mutually-perpendicular transmitter lines grounded at the ends. In this way, we made it possible to change the direction of the electrical and magnetic field polarization continuously. This approach allows realization of the technique of tensor measurements using the new modification of the CSRMT method. In permafrost areas, the hydrogenic taliks are widespread. These local objects are important in the context of study of environmental changes in the Arctic and can be successfully explored by the tensor CSRMT method. For the numerical modeling, a 2D model of the talik was used. Results of the interpretation of synthetic data showed the advantage of bimodal inversion using CSRMT curves of both TM and TE modes compared to separate inversion of TM and TE curves. These new data demonstrate the prospects of the tensor CSRMT method in the study of permafrost regions. The problems that can be solved using the CSRMT method in the Arctic permafrost regions are discussed.

Peculiarities of excitation of the Earth–ionosphere waveguide at frequencies above the frequency of the first transverse resonance

Experimental data on the registration of signals from tweek-atmospherics and an ionospheric source formed because of heating of the ionosphere at frequencies higher than the frequency of the first transverse resonance of the Earth–ionosphere waveguide (~1.8 kHz) are considered. It is shown that, far from the source, at frequencies near the resonance, almost complete circular left-hand polarization of the horizontal magnetic field is observed, and the angles of incidence are small and range from 10° to 35°. A joint analysis of observational data and simulation results showed that it is possible to calculate the effective reflection height from estimates of the incidence angle, which can be used to diagnose the lower ionosphere. But, in the case of an ionospheric source, it is important to take into account the inhomogeneity of its radiation pattern.

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

We study the Hii regions associated with the NGC 6334 molecular cloud observed in the submillimeter and taken as part of the B-fields In STar-forming Region Observations Survey. In particular, we investigate the polarization patterns and magnetic field morphologies associated with these Hii regions. Through polarization pattern and pressure calculation analyses, several of these bubbles indicate that the gas and magnetic field lines have been pushed away from the bubble, toward an almost tangential (to the bubble) magnetic field morphology. In the densest part of NGC 6334, where the magnetic field morphology is similar to an hourglass, the polarization observations do not exhibit observable impact from Hii regions. We detect two nested radial polarization patterns in a bubble to the south of NGC 6334 that correspond to the previously observed bipolar structure in this bubble. Finally, using the results of this study, we present steps (incorporating computer vision; circular Hough transform) that can be used in future studies to identify bubbles that have physically impacted magnetic field lines.

太阳极轨天文台

<p indent="0mm">Solar magnetic fields and related solar magnetic activities dominate the heliospheric environments from the near-Earth space, to the interplanetary space, and up to the interstellar boundary. The polar magnetic fields of the Sun and its dynamic processes are especially vital in the aspects of manifesting the internal dynamo of the Sun, and shaping magnetic fields in the heliosphere. But so far, almost all the solar satellites have been limited in the vicinity of the ecliptic plane. Due to the serious projection effect, the polar regions remain as the least-known mysterious territory of the Sun. The spacecraft of “Solar Polar-orbit Observatory (SPO)” has been designed to directly image the solar polar regions in an unprecedented way by traveling in a large solar inclination angle (≥ 80°) and a small ellipticity. Based on multi-band remote-sensing and <italic>in-situ</italic> measurements, the SPO will make breakthrough on the following top-level scientific objectives: (1) Provide decisive observations for solving the problem of the century—How the solar magnetic activity cycle originates that shapes the living environment of human beings; (2) provide direct observational supports for unveiling the origin, mechanism, and effect of the “primitive” high-speed solar wind that connects the Sun and celestial bodies in the solar system; (3) provide the necessary, complete, and self-consistent initial and boundary conditions for creating a data-driven global heliospheric numerical model that serves as the foundation for space weather prediction. To achieve these scientific objectives, the SPO will be equipped with six remote-sensing instruments and one <italic>in-situ</italic> instrument package. The remote-sensing instruments are Magnetic and Helioseismic Imager (MHI; FOV: 34′ (full disk)/17′ (high resolution); pixel resolution: 1″/0.5″; sensitivity: 10 G (longitudinal), 200 G (transverse); cadence: <sc>15 min;</sc> sensitivity of Doppler velocity: <sc>30 m/s;</sc> Cadence: <sc>1 min),</sc> Extreme Ultraviolet Solar Telescope (EUST; FOV: 51′; spatial resolution: 3.5″; imaging band: 19.3, 17.1, 13.1 and <sc>30.4 nm;</sc> cadence: <sc>1 min),</sc> Visible-light Coronagraph (VISCO; FOV: 0.69°–2.67° annular; pixel resolution: 4.8″; wave band: <sc>700±40 nm;</sc> cadence: <sc>2 min),</sc> Very Large Angle Coronagraph (VLACOR; FOV: 2.67°–24° annular; pixel resolution: 45″; wave band: <sc>600–750 nm;</sc> cadence: <sc>10 min</sc> (white light), <sc>60 min</sc> (polarization)), X-ray Imaging Telescope (XIT; FOV: 48′; angular resolution: 10″; energy range: Energy spectrum <sc>0.5–10 keV;</sc> spectral resolution: <sc>1 keV@6 keV;</sc> time resolution: <sc>5 s</sc> (common), <sc>1 s</sc> (burst)), and Low Frequency Radio Spectrometer (LFRS; frequency range: <sc>10 kHz–2.0 MHz</sc> and <sc>1.0–50 MHz;</sc> spectral resolution: <sc>≤5 kHz@2.0 MHz</sc> and <sc>≤0.1 MHz@50 MHz;</sc> time resolution: <sc>1 s;</sc> dynamic range: <sc>&gt;72 dB)</sc>. The <italic>in-situ</italic> instrument package includes Solar Wind Ion Analyzer (SWIA), Solar Energetic Particles Analyzer (SEPA), and Magnetometer (MAG).

Evolutionary implications of a magnetar interpretation for GLEAM-X J162759.5–523504.3

ABSTRACT The radio pulsar GLEAM-X J162759.5–523504.3 has an extremely long spin period ($P = 1091.17\, \mbox{s}$), and yet seemingly continues to spin-down rapidly ($\dot{P} &amp;lt; 1.2 \times 10^{-9}\, \mbox{ss}^{-1}$). The magnetic field strength that is implied, if the source is a neutron star undergoing magnetic dipole braking, could exceed $10^{16}\, \mbox{G}$. This object may therefore be the most magnetized neutron star observed to date. In this paper, a critical analysis of a magnetar interpretation for the source is provided. (i) A minimum polar magnetic field strength of $B \sim 5 \times 10^{15}\, \mbox{G}$ appears to be necessary for the star to activate as a radio pulsar, based on conventional ‘death valley’ assumptions. (ii) Back-extrapolation from magnetic braking and Hall–plastic–Ohm decay suggests that a large angularize momentum reservoir was available at birth to support intense field amplification. (iii) The observational absence of X-rays constrains the star’s field strength and age, as the competition between heating from field decay and Urca cooling implies a surface luminosity as a function of time. If the object is an isolated, young ($\sim 10\, \mbox{kyr}$) magnetar with a present-day field strength of $B \gtrsim 10^{16}\, \mbox{G}$, the upper limit ($\approx 10^{30}\, \mbox{erg s}^{-1}$) set on its thermal luminosity suggests it is cooling via a direct Urca mechanism.