General solution for the vacuum electromagnetic field in the surroundings of a rotating star

Bonazzola, S.; Mottez, Fabrice; Heyvaerts, J.

doi:10.1051/0004-6361/201424659

Cited by 16 publications

(27 citation statements)

References 22 publications

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“…They found that the large density and pressure make the crust very strong and rigid, capable of supporting |ǫ| 4 × 10 −6 (assuming canonical neutron star mass and radius) before cracking suddenly in a collective manner (rather than yielding continuously). If we assume that the initial magnetic field does not deform the star sufficiently to crack the crust, then this limit translates to B (Young, Manchester, & Johnston 1999;Camilo et al 2000;Medin & Lai 2010), the anomalous braking index of some radio pulsars (Barsukov & Tsygan 2010), and the substructures found in some pulsar signals (Bonazzola, Mottez, & Heyvaerts 2015;Pétri 2015). While the dipole component of the magnetic field can be inferred from the observed spin-down rate, the putative higher-order multipoles contribute small corrections of order (2πνR * /c) 2 to the torque and cannot be measured directly.…”

Section: Axp 1e 2259+586 Anti-glitchmentioning

confidence: 99%

Interpreting the AXP 1E 2259+586 antiglitch as a change in internal magnetization

Mastrano

Suvorov

Melatos

2015

Mon. Not. R. Astron. Soc.

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The sudden spin-down event ('anti-glitch') observed in AXP 1E 2259+586 on 2012 April 21 was arguably caused by a decay of its internal toroidal magnetic field component, which turns a stable prolate configuration into an unstable one. We refine previous models of this process by modelling the star's magnetic field self-consistently as a 'twisted torus' configuration in non-barotropic equilibrium (which allows us to explore a greater range of equilibrium configurations). It is shown that, if the star's magnetic field is purely dipolar, the change in the toroidal field strength required to produce an anti-glitch of the observed size can be ∼ 10 times larger than previously calculated. If the star has a quadrupolar magnetic field component, then an anti-glitch of similar magnitude can be produced via a decay of the quadrupole component, in addition to a decay of the toroidal component. We show that, if the quadrupole component decays, the minimum initial toroidal field strength and the change in toroidal field strength needed to produce the observed anti-glitch are lower than in the pure dipole twisted torus. In addition, we predict the maximum anti-glitch sizes, assuming that they are caused by a change in ellipticity, in four glitching magnetars and discuss the implications for energetics of accompanying X-ray bursts.

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Section: Axp 1e 2259+586 Anti-glitchmentioning

confidence: 99%

Interpreting the AXP 1E 2259+586 antiglitch as a change in internal magnetization

Mastrano

Suvorov

Melatos

2015

Mon. Not. R. Astron. Soc.

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“…We suppose that there is the misalignment angle α between the rotational axis and the accretion column along magnetic axis so as to generate GW emission [43]. In the case of rigid rotation about a nonprincipal axis [18], the mass quadrupole moment can be represented as…”

Section: Accretion Columns and Gw Radiationmentioning

confidence: 99%

“…Therefore, the maximum amplitude of GW radiation produced from this mass quadrupole moment Q at a distance D of the source to the observer is given by [29,43]…”

Section: Accretion Columns and Gw Radiationmentioning

confidence: 99%

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Gravitational waves from newborn accreting millisecond magnetars

Zhong¹,

Dai²,

Li³

2019

Phys. Rev. D

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Two accretion columns have been argued to form over the surface of a newborn millisecond magnetar for an extremely high accretion rate 1.8 × 10 −2 M⊙ s −1 that may occur in the corecollapse of a massive star. In this paper, we investigate the characteristics of these accretion columns and their gravitational wave (GW) radiation. For a typical millisecond magnetar (surface magnetic field strength B ∼ 10 15 G and initial spin period P ∼ 1 ms), we find (1) its accretion columns are cooled via neutrinos and can reach a height ∼ 1 km over the stellar surface; (2) its column-induced characteristic GW strain is comparable to the sensitivities of the next generation ground-based GW detectors within a horizon ∼ 1 Mpc; (3) the magnetar can survive only a few tens of seconds; (4) during the survival timescale, the height of the accretion columns increases rapidly to the peak and subsequently decreases slowly; (5) the column mass, characteristic GW strain, and maximum GW luminosity have simultaneous peaks in a similar rise-fall evolution. In addition, we find that the magnetar's spin evolution is dominated by the column accretion torque. A possible association with failed supernova is also discussed. R 125/56 12 M ⊙ ,(7)

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“…Furthermore, measurements of cyclotron resonant scattering lines [33] and pulse fractions in surface X-ray emissions [34] suggest that some neutron stars have local magnetic field strengths well in excess ( 3 orders of magnitude in some cases, such as 1E 1207.4-5209 [35]) of their spindown limits. Since magnetic stresses are known to induce mass density asymmetries within a star [36,37], magnetised neutron stars are therefore expected, in principle, to be excellent sources of continuous GWs [38,39]. In particular, these density asymmetries naturally lead to the generation of mass multipole moments, whose magnitude is proportional to the magnetic energy [20,40,41].…”

Section: Introductionmentioning

confidence: 99%

Monopolar and quadrupolar gravitational radiation from magnetically deformed neutron stars in modified gravity

Suvorov¹

2018

Phys. Rev. D

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Some modified theories of gravity are known to predict monopolar, in addition to the usual quadrupolar and beyond, gravitational radiation in the form of 'breathing' modes. For the same reason that octupole and higher-multipole terms often contribute negligibly to the overall wave strain, monopole terms tend to dominate. We investigate both monopolar and quadrupolar continuous gravitational radiation from neutron stars deformed through internal magnetic stresses. We adopt the Parameterised-Post-Newtonian formalism to write down equations describing the leadingorder stellar properties in a theory-independent way, and derive some exact solutions for stars with mixed poloidal-toroidal magnetic fields. We then turn to the specific case of scalar-tensor theories to demonstrate how observational upper limits on the gravitational-wave luminosity of certain neutron stars may be used to place constraints on modified gravity parameters, most notably the Eddington parameter γ. For conservative, purely poloidal models with characteristic field strength given by the spindown minimum, upper limits for the Vela pulsar yield 1 − γ 4.2 × 10 −3 . For models containing a strong toroidal field housing ∼ 99% of the internal magnetic energy, we obtain the bound 1 − γ 8.0 × 10 −7 . This latter bound is an order of magnitude tighter than those obtained from current Solar system experiments, though applies to the strong-field regime.

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General solution for the vacuum electromagnetic field in the surroundings of a rotating star

Cited by 16 publications

References 22 publications

Interpreting the AXP 1E 2259+586 antiglitch as a change in internal magnetization

Interpreting the AXP 1E 2259+586 antiglitch as a change in internal magnetization

Gravitational waves from newborn accreting millisecond magnetars

Monopolar and quadrupolar gravitational radiation from magnetically deformed neutron stars in modified gravity

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