Repair of thoracic aorta and subsequent pregnancy

Levin, Hilton; Heifetz, M

doi:10.1111/j.1365-2044.1988.tb05495.x

Cited by 4 publications

(7 citation statements)

References 3 publications

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“…3 Therefore, given the knowledge of the internal magnetic field, one should use ρ c ≃ x p ρ n in Eq. ( 1) to determine the frequency of the lowest QPO which, according to Levin (2007), corresponds to the turning point of the Alfven continuum in the core. For Levin's the simplest computable magnetar model (uniform internal magnetic field and density), with the typical magnetar parameters, B = 10 15 G, R = 10km, ρ = 10 15 g/cm 3 and x p = 0.05, Eq.…”

Section: Hydromagnetic Waves In Magnetarsmentioning

confidence: 99%

“…Levin (2006) has shown that for a magnetar-strength field the crustal motion [which is thought to be either powering power the flare (Thompson & Duncan 1995) or responding to a global reconnection event in the magnetosphere (Lyutikov 2003)] would excite the core Alfven waves on the timescale of several oscillation periods. Since then, a significant body of theoretical work has been devoted to a study of global magnetar vibrations, which would involve both hydromagnetic waves in the core and elasto-magnetic shear waves in the crust [Glampedakis, Samuelsson, & Andersson 2006, Levin 2007 (from here on L07), Sotani, Kokkotas, & Stergioulas 2007, Lee 2007]. In particular, L07 has argued that the longlived low-frequency QPOs are associated with the special spectral points of the Afven continuum in the magnetar core.…”

Section: Introductionmentioning

confidence: 99%

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Hydromagnetic waves in a superfluid neutron star with strong vortex pinning

Hoven

Levin

2008

Monthly Notices of the Royal Astronomical Society

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Neutron star cores may be the hosts of a unique mixture of a neutron superfluid and a proton superconductor. Compelling theoretical arguments have been presented over the years that if the proton superconductor is of type II, then the superconductor fluxtubes and superfluid vortices should be strongly coupled and hence the vortices should be pinned to the protonelectron plasma in the core. We explore the effect of this pinning on the hydromagnetic waves in the core, and discuss two astrophysical applications of our results. (i) We show that, even in the case of strong pinning, the core Alfvén waves thought to be responsible for the lowfrequency magnetar quasi-periodic oscillations (QPO) are not significantly mass loaded by the neutrons. The decoupling of ∼0.95 of the core mass from the Alfvén waves is, in fact, required in order to explain the QPO frequencies, for simple magnetic geometries and for magnetic fields not greater than 10 15 G.(ii) We show that in the case of strong vortex pinning, hydromagnetic stresses exert stabilizing influence on the Glaberson instability, which has recently been proposed as a potential source of superfluid turbulence in neutron stars.

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Section: Hydromagnetic Waves In Magnetarsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydromagnetic waves in a superfluid neutron star with strong vortex pinning

Hoven

Levin

2008

Monthly Notices of the Royal Astronomical Society

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“…For the present study, we adopt the same phenomenological family of crust EOS constructed by Oyamatsu & Iida (2003, 2007, the so-called OI-EOSs. For this family of EOS the bulk energy per nucleon, for zero-temperature uniform nuclear matter, is expressed in the vicinity of the saturation density for the symmetric nuclear matter, n 0 , as a function of the baryon number density, n b , and the asymmetry parameter, α, as…”

Section: Crust Equilibrium and Torsional Oscillationsmentioning

confidence: 99%

“…In this study, we worked under the assumption that the strength of the magnetic field in GRB 200415A is < ∼ 10 15 G, so that torsional oscillations have a short damping time, but the frequencies are still close to the values of pure crustal oscillations. For B ≥ 10 15 G, there is a strong shift in the torsional oscillation frequencies, and the damping due to the "continuous" spectrum is even stronger, if one considers particular geometries for the magnetic field (Levin 2007;Colaiuda et al 2009;van Hoven & Levin 2011;Colaiuda & Kokkotas 2011;Gabler et al 2012Gabler et al , 2018. For mixed poloidal-toroidal fields, the magnetoelastic oscillations spectrum is becoming discrete (Colaiuda & Kokkotas 2012).…”

Section: Appendix A: Magnetic Effects On the Crustal Torsional Oscill...mentioning

confidence: 99%

“…In addition, the analysis of the afterglow spectra in magnetar giant flares (SGR 1900+14 andSGR 1806-20) demonstrated a rich spectrum, the so-called quasi-periodic oscillations (QPOs) (Strohmayer & Watts 2005;Israel et al 2005;Strohmayer & Watts 2006). The analysis suggested that the QPOs were due to magnetoelastic oscillation modes (Levin 2007;Sotani et al 2007;Steiner & Watts 2009;Gabler et al 2011;Gearheart et al 2011;Sotani et al 2012;Colaiuda & Kokkotas 2012;Gabler et al 2012;Sotani et al 2013;Gabler et al 2013Gabler et al , 2016Gabler et al , 2018 which provided another opportunity for constraining the parameters of neutron stars.…”

Section: Introductionmentioning

confidence: 99%

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Neutron star mass-radius constraints using the high-frequency QPOs of GRB 200415A

Sotani¹,

Kokkotas²,

Stergioulas³

2023

Preprint

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Context. Quasi-periodic oscillations (QPOs) observed in a giant flare of a strongly magnetized neutron star (magnetar), are carrying crucial information for extracting the neutron star properties. Aims. The aim of the study is to constrain the mass and radius of the neutron star model for GRB 200415A, by identifying the observed QPOs with the crustal torsional oscillations together with the experimental constraints on the nuclear matter properties. Methods. The frequencies of the crustal torsional oscillations are determined by solving the eigenvalue problem with the Cowling approximation, assuming a magnetic field of about 10 15 G. Results. We find that the observed QPOs can be identified with several overtones of crustal oscillations, for carefully selected combinations of the nuclear saturation parameters. Thus, we can inversely constrain the neutron star mass and radius for GRB 200415A by comparing them to the values of nuclear saturation parameters obtained from terrestrial experiments. Conclusions. We impose further constraints on the neutron star mass and radius while the candidate neutron star models are consistent with the constraints obtained from other available astronomical and experimental observations.

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Computational general relativistic force-free electrodynamics

Mahlmann

Aloy

Mewes

et al. 2021

A&A

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General relativistic force-free electrodynamics is one possible plasma-limit employed to analyze energetic outflows in which strong magnetic fields are dominant over all inertial phenomena. The amazing images of black hole (BH) shadows from the Galactic Center and the M87 galaxy provide a first direct glimpse into the physics of accretion flows in the most extreme environments of the universe. The efficient extraction of energy in the form of collimated outflows or jets from a rotating BH is directly linked to the topology of the surrounding magnetic field. We aim at providing a tool to numerically model the dynamics of such fields in magnetospheres around compact objects, such as BHs and neutron stars. To do so, we probe their role in the formation of high energy phenomena such as magnetar flares and the highly variable teraelectronvolt emission of some active galactic nuclei. In this work, we present numerical strategies capable of modeling fully dynamical force-free magnetospheres of compact astrophysical objects. We provide implementation details and extensive testing of our implementation of general relativistic force-free electrodynamics in Cartesian and spherical coordinates using the infrastructure of the EINSTEIN TOOLKIT. The employed hyperbolic/parabolic cleaning of numerical errors with full general relativistic compatibility allows for fast advection of numerical errors in dynamical spacetimes. Such fast advection of divergence errors significantly improves the stability of the general relativistic force-free electrodynamics modeling of BH magnetospheres.

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Repair of thoracic aorta and subsequent pregnancy

Cited by 4 publications

References 3 publications

Hydromagnetic waves in a superfluid neutron star with strong vortex pinning

Hydromagnetic waves in a superfluid neutron star with strong vortex pinning

Neutron star mass-radius constraints using the high-frequency QPOs of GRB 200415A

Computational general relativistic force-free electrodynamics

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