The Dipole Magnetic Field and Spin-down Evolutions of the High Braking Index Pulsar PSR J1640–4631

Here, we summarize our recent work on the evolution of magnetic field and spin-down of young pulsars including high-B pulsars and magnetars. Our work includes the following three parts: (a) Based on the estimated ages of their potentially associated supernova remnants (SNRs), we estimate the values of the mean braking indices of eight magnetars with SNRs and find that five magnetars have smaller mean braking indices of 1 < n < 3, and we interpret them within a combination of magnetodipole radiation and wind-aided braking. (b) The low braking index of n = 0.9(2) for PSR J1734-3333 could undergo a supercritical accretion soon after its formation in a supernova explosion. The buried multipole magnetic fields will merge into a dipole magnetic field. Retaining the current field growth index = 1.34, this pulsar will become a magnetar with dB p ∼6.2(2) × 10 14 G and dB p ∼1.06(4) × 10 15 G after 50 kyrs and 100 kys, respectively. (c) By introducing a mean rotation energy conversion coefficient and combining the pulsar's high-energy and timing observations with a reliable nuclear equation of state, we estimate the initial spin period, initial dipole magnetic field, and true age of PSR J1640-4631. For this source, its measured high braking index n = 3.15(3) is attributed to a long-term dipole magnetic field decay, and its soft X-ray emission is attributed to anisotropic heating. K E Y W O R D SPSR J1640-4631, toroidal magnetic field, TPW heating

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“…Long‐term rotational evolution of PSR J1640‐4631 dominated by the dipole magnetic field decay. This figure is cited from Gao et al ()…”

Section: High Braking Index Pulsar Psr J1640‐4631mentioning

confidence: 99%

The evolution of magnetic field and spin‐down of young pulsars

2019

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“…Manchester & Taylor 1977;Lyne & Graham-Smith 2012;Gao et al 2016Gao et al , 2017. Alternatively, for BeXRBs, the observed NS spin frequency is modulated by the orbital motion, which allows measurement of the orbital parameters of the binary system (e.g., Li et al 2011;Takagi et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Pulse phase-resolved analysis of SMC X-3 during its 2016–2017 super-Eddington outburst

Zhao

Weng

et al. 2018

Astrophys Space Sci

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The Be X-ray pulsar SMC X-3 underwent an extra long and ultraluminous giant outburst from 2016 August to 2017 March. The peak X-ray luminosity is up to ∼ 10 39 erg/s, suggesting a mildly superEddington accretion onto the strongly magnetized neutron star. It therefore bridges the gap between the Galactic Be/X-ray binaries (L peak X ≤ 10 38 erg/s) and the ultraluminous X-ray pulsars (L peak X ≥ 10 40 erg/s) found in nearby galaxies. A number of observations were carried out to observe the outburst. In this paper, we perform a comprehensive phase-resolved analysis on the high quality data obtained with the Nustar and XMM-Newton, which were observed at a high and intermediate luminosity levels. In order to get a better understanding on the evolution of the whole extreme burst, we take the Swift results at the low luminosity state into account as well. At the early stage of outburst, the source shows a double-peak pulse profile, the second main peak approaches the first one and merges into the single peak at the low luminosity. The second main peak vanishes beyond 20 keV, and its radiation becomes much softer than that of the first main peak. The line widths of fluorescent iron line vary dramatically with phases, indicating a complicated geometry of accretion flows. In contrast to the case at low luminosity, the pulse fraction increases with the photon energy. The significant small pulse fraction detected below 1 keV can be interpreted as the existence of an additional thermal component located at far away from the central neutron star.

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“…Our previous work (Li et al ) (“Li16” in short) was devoted to considering the electron Fermi energy and an associated value of the electron number fraction as functions of the matter density ρ within different layers of NS's crust and core of a common NS with B ≪ B cr (Li et al ; Gao et al ). Since the main purpose of this paper is to reinvestigate Y e and E F ( e ) inside an NS by revising Li16, it is necessary to briefly review Li16, which is provided below.…”

Section: Introductionmentioning

confidence: 99%

Reinvestigation of the electron fraction and electron Fermi energy of neutron star

et al. 2017

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In this work, we reinvestigate the electron fraction Ye and electron Fermi energy EF(e) of neutron stars, based on our previous work, in which we first deduce a special solution to EF(e), and then obtain several useful analytical formulae for Ye and matter density ρ within classical models and the relativistic mean‐field (RMF) theory using numerical fitting. The advantages of this formalism include the following: (a) Linear functions are substituted for the nonlinear exponential functions used in the previous work. This method may be simpler and closer to realistic equation of state (EoS) of a neutron star (NS) because there are linear or quasi‐linear relationships between number fractions of leptons and matter density, which can be seen by solving NS EoS. (b) We introduce a dimensionless variable ϱ (ϱ = ρ/ρ0, ρ0 is the standard saturated nuclear density), which greatly reduces the scope of the fitting coefficients. (c) We present numerical errors including absolute and relative deviations between the data and fit. By numerical simulations, we obtain several analytical formulae for Ye and ρ for both APR98 and RMF models. Combining these analytical formulae with the special solution, we can calculate the value of EF(e) for any given matter density. Since Ye and EF(e) are important in assessing the cooling rate of an NS and the possibility of kaon/pion condensation in the NS's interior, this formalism could be useful in the future studies on the thermal evolution of an NS.

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The Dipole Magnetic Field and Spin-down Evolutions of the High Braking Index Pulsar PSR J1640–4631

Cited by 88 publications

References 93 publications

The evolution of magnetic field and spin‐down of young pulsars

The evolution of magnetic field and spin‐down of young pulsars

Pulse phase-resolved analysis of SMC X-3 during its 2016–2017 super-Eddington outburst

Reinvestigation of the electron fraction and electron Fermi energy of neutron star

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