Stellar structure of magnetars
16 Mar 2016-Science China-physics Mechanics & Astronomy (Science China Press)-Vol. 59, Iss: 4, pp 1-5
TL;DR: In this article, the authors investigated the effects of magnetic fields on the structure of isolated magnetars and found that the magnetar mass and radius are weakly enhanced by the strong magnetic fields.
Abstract: Magnetars are strong magnetized neutron stars which could emit quiescent X-ray, repeating burst of soft gamma ray, and even the giant flares. We investigate the effects of magnetic fields on the structure of isolated magnetars. The stellar structure together with the magnetic field configuration can be obtained at the same time within a self-consistent procedure. The magnetar mass and radius are found to be weakly enhanced by the strong magnetic fields. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars.
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TL;DR: This work shows that the highly stable, non-toxic and earth-abundant material, ZrSiS, has an electronic band structure that hosts several Dirac cones that form a Fermi surface with a diamond-shaped line of Dirac nodes, making it a very promising candidate to study Dirac electrons, as well as the properties of lines ofDirac nodes.
Abstract: Materials harbouring exotic quasiparticles, such as massless Dirac and Weyl fermions, have garnered much attention from physics and material science communities due to their exceptional physical properties such as ultra-high mobility and extremely large magnetoresistances. Here, we show that the highly stable, non-toxic and earth-abundant material, ZrSiS, has an electronic band structure that hosts several Dirac cones that form a Fermi surface with a diamond-shaped line of Dirac nodes. We also show that the square Si lattice in ZrSiS is an excellent template for realizing new types of two-dimensional Dirac cones recently predicted by Young and Kane. Finally, we find that the energy range of the linearly dispersed bands is as high as 2 eV above and below the Fermi level; much larger than of other known Dirac materials. This makes ZrSiS a very promising candidate to study Dirac electrons, as well as the properties of lines of Dirac nodes.
661 citations
01 Feb 2018
TL;DR: The realization of Dirac and Weyl physics in solids has made topological materials one of the main focuses of condensed matter physics as discussed by the authors, and the topic of topological nodal line semimetals, mat...
Abstract: The realization of Dirac and Weyl physics in solids has made topological materials one of the main focuses of condensed matter physics. Recently, the topic of topological nodal line semimetals, mat...
137 citations
TL;DR: In this article, an annular bright-field (ABF) scanning TEM (STEM), in which the contrast has a low scaling rate with the atomic number, has been proven to be a robust technique for simultaneous imaging of light and heavy elements.
Abstract: Rechargeable batteries are being intensively investigated in an attempt to solve the energy issues while meeting the environmental demands. Even though Li-ion batteries (LIB) with high energy and light weight have been commercialized within the last 20 years, these devices currently require higher energy density, output power and sustainability characteristics. The atomic behavior of Li ion that determines LIB's performance is hardly characterized by transmission electron microscopy (TEM) owing to its weak electron-scattering power. In this sense, annular bright-field (ABF) scanning TEM (STEM), in which the contrast has a low scaling rate with the atomic number, has been proven to be a robust technique for simultaneous imaging of light and heavy elements. The s-state model, in which electron channeling along the atomic column allows the intensity to be focusing in the forward direction, has successfully explained the theory of ABF contrast. Furthermore, the detector angle range, the defocus-thickness dependence and the accelerating voltage (among other parameters) were discussed for optimized imaging conditions. ABF-STEM has shown powerful capabilities in resolving the atomic structure and the chemistry of electrodes (e.g. Li-ion occupation and diffusion, phase transformation and interface reaction), thereby providing critical insights into the physical properties, the battery performance and the design guidance of LIB. The future directions of ABF imaging for the characterization of LIB materials were also reviewed.
14 citations
TL;DR: In this paper, an inclined cable excited by a massive non-ideal moving deck is investigated in an asymptotically coupled formulation for understanding cable-deck dynamic interactions.
Abstract: A moving deck is an important (kinematic) excitation source for the inclined cable in cable-stayed bridges. In ideal cases, the deck motion is assumed to be harmonic oscillation and cable’s dynamic effects on the deck are neglected. As a refined version, an inclined cable excited by a massive non-ideal moving deck, i.e., the deck’s oscillation, is slowly modulated by the cable and thus not exactly harmonic is investigated in an asymptotically coupled formulation for understanding cable–deck dynamic interactions. More explicitly, by ordering the deck/cable mass ratio as a large parameter, the coupled system is reduced using asymptotic approximations and multi-scale expansions. After neglecting the reduced model’s nonlinear terms, firstly, cable–deck linear coupled modes are obtained, leading to two different kinds of linear modal dynamics, i.e., the cable-dominated one and the deck-dominated one, whose asymptotic characteristics are also revealed. Then cable’s forced nonlinear vibrations, excited by the deck’s modulated oscillation (i.e., non-ideal moving deck), are fully investigated. Nonlinear frequency responses of the cable–deck coupled system are found, and the dynamic effects on the cable’s periodic and quasi-periodic behaviors, due to cable–deck coupling (characterized by the deck/cable mass ratio), cable’s inclinations, and boundary damping, are also presented.
13 citations
TL;DR: The results further verify the previous theoretical research of generating multiferroics experimentally paving a way for designing or developing the novel magnetoelectric devices based on manganite ferromagnets.
Abstract: In this paper, [(La0.9Sr0.1MnO3)n/(Pa0.9Ca0.1MnO3)n/(La0.9Sb0.1MnO3)n]m superlattices films have been deposited on (001) Nb:SrTiO3 substrates by a laser molecular-beam epitaxy technology. Expected ferroelectricity arise at well-defined tricolor superlattice at low temperature, composed of transition metal manganite, which is absent in the single-phase compounds. Furthermore, the ferroelectric properties of the superlattices are enhanced by increasing the periodicity m, which may be attributed to the accumulation of the polarization induced by the frustration. As for the magnetic hysteresis loop characteristics of the multilayer structures, the saturation magnetization and magnetic coercivity of films present definitely a strong periodic dependence. It also indicates that the frustration may exist in the tricolor superlattice. Our results further verify the previous theoretical research of generating multiferroics experimentally paving a way for designing or developing the novel magnetoelectric devices based on manganite ferromagnets.
10 citations
References
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04 Dec 2013
TL;DR: Beringer et al. as mentioned in this paper presented a review of particle physics using data from previous editions, plus 2658 new measurements from 644 papers, and summarized searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles.
Abstract: Phys. Rev. D 86, 010001 REVIEW OF PARTICLE PHYSICS* Particle Data Group Abstract This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, V cb & V ub , Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov. DOI: 10.1103/PhysRevD.86.010001 The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D. This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012). c 2012 Regents of the University of California ∗ The publication of the Review of Particle Physics is supported by the Director, Office of Science, Office of High Energy and Nuclear Physics, the Division of High Energy Physics of the U.S. Department of Energy under Contract No. DE–AC02–05CH11231; by the U.S. National Science Foundation under Agreement No. PHY-0652989; by the European Laboratory for Particle Physics (CERN); by an implementing arrangement between the governments of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) and the United States (DOE) on cooperative research and development; and by the Italian National Institute of Nuclear Physics (INFN).
3,544 citations
TL;DR: Radio timing observations of the binary millisecond pulsar J1614-2230 that show a strong Shapiro delay signature are presented and the pulsar mass is calculated to be (1.97 ± 0.04)M⊙, which rules out almost all currently proposed hyperon or boson condensate equations of state.
Abstract: Neutron stars comprise the densest form of matter known to exist in our Universe, but their composition and properties are uncertain. Measurements of their masses and radii can constrain theoretical predictions of their composition, but so far it has not been possible to rule out many predictions of 'exotic' non-nucleonic components. Here, radio timing observations of the binary millisecond pulsar J1614-2230 are presented, allowing almost all currently proposed hyperon or boson condensate equations of state to be ruled out.
3,338 citations
Max Planck Society1, McGill University2, University of Toronto3, University of Manchester4, University of Sheffield5, German Aerospace Center6, University of Amsterdam7, ASTRON8, Lebedev Physical Institute9, University of Warwick10, West Virginia University11, University of Virginia12, National Radio Astronomy Observatory13, University of British Columbia14
TL;DR: Pulsar J0348+0432 is only the second neutron star with a precisely determined mass of 2 M☉
Abstract: Many physically motivated extensions to general relativity (GR) predict significant deviations at energies present in massive neutron stars. We report the measurement of a 2.01 \(\pm \) 0.04 solar mass (M\(_\odot \)) pulsar in a 2.46-h orbit around a 0.172 \(\pm \) 0.003 M\(_\odot \) white dwarf. The high pulsar mass and the compact orbit make this system a sensitive laboratory of a previously untested strong-field gravity regime. Thus far, the observed orbital decay agrees with GR, supporting its validity even for the extreme conditions present in the system. The resulting constraints on deviations support the use of GR-based templates for ground-based gravitational wave detection experiments. Additionally, the system strengthens recent constraints on the properties of dense matter and provides novel insight to binary stellar astrophysics and pulsar recycling.
3,224 citations
TL;DR: In this article, a biennial review summarizes much of particle physics using data from previous editions, plus 2158 new measurements from 551 papers, they list, evaluate and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons.
Abstract: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.
2,788 citations
TL;DR: In this article, the decay rate of the core field is a very strong function of temperature and therefore of the magnetic flux density, which is not present in the decay of the weaker fields associated with ordinary radio pulsars.
Abstract: We calculate the quiescent X-ray, neutrino, and Alfven wave emission from a neutron star with a very strong magnetic field, Bdipole ~ 1014 − 1015 G and Binterior ~ (5–10) × 1015 G. These results are compared with observations of quiescent emission from the soft gamma repeaters and from a small class of anomalous X-ray pulsars that we have previously identified with such objects. The magnetic field, rather than rotation, provides the main source of free energy, and the decaying field is capable of powering the quiescent X-ray emission and particle emission observed from these sources. New features that are not present in the decay of the weaker fields associated with ordinary radio pulsars include fracturing of the neutron star crust, strong heating of its core, and effective suppression of thermal conduction perpendicular to the magnetic field. As the magnetic field is forced through the crust by diffusive motions in the core, multiple small-scale fractures are excited, as well as a few large fractures that can power soft gamma repeater bursts. The decay rate of the core field is a very strong function of temperature and therefore of the magnetic flux density. The strongest prediction of the model is that these sources will show no optical emissions associated with X-ray heating of an accretion disk.
1,128 citations