The hyperon coupling constants and the surface gravitational redshift of massive neutron stars

Zhao, Xian-Feng

doi:10.1016/j.cjph.2019.11.024

Cited by 5 publications

(2 citation statements)

References 34 publications

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“…The largest sample of measured NS masses available for analysis is publicly accessible online at http://www.stellarcollapse.org/, from which one can get a range of about (1-2)M for the observational NS masses. To date, the relativistic-mean-field (RMF) theory has become a standard method to study nuclear matter and finite-nuclei properties [44][45][46][47][48], but it has not been possible to fit masses in the RMF framework with a precision at all comparable to what was achieved with Skyrme functionals (Pearson et al (2018) [33]). At high densities the symmetry energy of BSk26 increases much less steeply than that of BSk24, given the much softer EoS of NeuM to which it was fitted (Pearson et al 2018).…”

Section: Theoretical Model Of Dipole Magnetic Field Evolutionmentioning

confidence: 99%

Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

et al. 2020

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Young pulsars are thought to be highly magnetized neutron stars (NSs). The crustal magnetic field of a NS usually decays at different timescales in the forms of Hall drift and Ohmic dissipation. The magnetization parameter ω B τ is defined as the ratio of the Ohmic timescale τ O h m to the Hall drift timescale τ H a l l . During the first several million years, the inner temperature of the newly born neutron star cools from T = 10 9 K to T = 1.0 × 10 8 K, and the crustal conductivity increases by three orders of magnitude. In this work, we adopt a unified equations of state for cold non-accreting neutron stars with the Hartree–Fock–Bogoliubov method, developed by Pearson et al. (2018), and choose two fiducial dipole magnetic fields of B = 1.0 × 10 13 G and B = 1.0 × 10 14 G, four different temperatures, T, and two different impurity concentration parameters, Q, and then calculate the conductivity of the inner crust of NSs and give a general expression of magnetization parameter for young pulsars: ω B τ ≃ ( 1 − 50 ) B 0 / ( 10 13 G) by using numerical simulations. It was found when B ≤ 10 15 G, due to the quantum effects, the conductivity increases slightly with the increase in the magnetic field, the enhanced magnetic field has a small effect on the matter in the low-density regions of the crust, and almost has no influence the matter in the high-density regions. Then, we apply the general expression of the magnetization parameter to the high braking-index pulsar PSR J1640-4631. By combining the observed arrival time parameters of PSR J1640-4631 with the magnetic induction equation, we estimated the initial rotation period P 0 , the initial dipole magnetic field B 0 , the Ohm dissipation timescale τ O h m and Hall drift timescale τ H a l l . We model the magnetic field evolution and the braking-index evolution of the pulsar and compare the results with its observations. It is expected that the results of this paper can be applied to more young pulsars.

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Section: Theoretical Model Of Dipole Magnetic Field Evolutionmentioning

confidence: 99%

Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

et al. 2020

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“…However, many of us face the questions: are there new degrees of freedom such as hyperons besides nucleons in neutron stars? What the kind of interactions would be allowed the appearance of the new degrees of freedom in the massive neutron stars (Xia et al 2014;Vidaña 2019;Zhao 2020;Khadkikar et al 2022;Zhao & Liu 2022;Sun et al 2023)?…”

Section: Introductionmentioning

confidence: 99%

Probing into the Possible Range of the U Bosonic Coupling Constants in Neutron Stars Containing Hyperons

Diao

Wang

et al. 2023

Res. Astron. Astrophys.

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The range of the U bosonic coupling constants in neutron star matter is a very interesting but still unsolved problem which has multifaceted influences in nuclear physics, particle physics, astrophysics and cosmology.The combination of the theoretical numerical simulation and the recent observations provides a very good opportunity to solve this problem. In the present work, the range of the U bosonic coupling constants is inferred based on the three relations of the mass-radius, mass-frequency and mass-tidal deformability in neutron star containing hyperons using the GM1, TM1 and NL3 parameter sets under the two flavor symmetries of the SU(6) and SU(3) in the framework of the relativistic mean field theory. Combined with observations from PSRs J1614-2230, J0348+0432, J2215-5135, J0952-0607, J0740+6620, J0030-0451, J1748-2446ad, XTE J1739-285, GW170817 and GW190814 events, our numerical results show that the U bosonic coupling constants may tend to be within the range from 0 to 20 GeV$^{-2}$ in neutron star containing hyperons. Moreover, the numerical results of the three relations obtained by the SU(3) symmetry are better in accordance with observation data than those obtained by the SU(6) symmetry. The results will help us to improve the strict constraints of the equation of state for neutron stars containing hyperons.

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Explaining high braking indices of magnetarsSGR0501+4516 and1E2259+586 using the double magnetic‐dipole model

et al. 2021

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In this paper, we attribute high braking indices n > 3 of two magnetars SGR 0501+4516 and 1E 2259+586 to the decrease in their inclination angles using the double magnetic‐dipole model proposed by Hamil et al. (2016). In this model, there are two magnetic moments inside a neutron star—one is generated by the rotation effect of a charged sphere, M1, and the other is generated by the magnetization of ferromagnetically ordered material, M2. Our calculations indicate that the magnetic moment M2 would evolve toward alignment with the spin axis of the two magnetars and cause their magnetic inclination angles to decrease. We also define a ratio η = M2/M1, which reflects the magnetization degree, and find that the values of η of the two magnetars are about two orders of magnitude higher than that of rotationally powered pulsar PSR J1640‐4631 with n = 3.15(3), assuming that they have the same rate of decrease in their inclination angles.

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The hyperon coupling constants and the surface gravitational redshift of massive neutron stars

Cited by 5 publications

References 34 publications

Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

Probing into the Possible Range of the U Bosonic Coupling Constants in Neutron Stars Containing Hyperons

Explaining high braking indices of magnetarsSGR0501+4516 and1E2259+586 using the double magnetic‐dipole model

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