Addendum: Influence of the nuclear matter equation of state on the r-mode instability using the finite-range simple effective interaction (2018 J. Phys. G: Nucl. Part. Phys. 45 055202)

Abstract

In a previous work, Pattnaik S P et al (2018 J. Phys. G: Nucl. Part. Phys. 45 055202), we studied the spin-down rate under the influence of emission of gravitational waves due to the r-mode for stellar masses of 1.4 M e and 1.8 M e . The sensitivity of the results to the slope parameter of the nuclear symmetry energy, L, and to the nuclear matter incompressibility, K, was also studied. In the present work, we report the intensity of the emitted gravitational waves in terms of the amplitude of the strain tensor, with particular emphasis on the Land K-dependence of the equation of state.Keywords: simple effective interaction, r-mode instability, equation of state, neutron star pulsar, slope parameter, the amplitude of the strain tensor The recent detection [2] of gravitational waves (GW) may be of enormous value in helping to solve many relevant queries relating to the composition and structure of neutron stars (NSs). The r-modes in NSs are the mechanism for continuous emission of GW by the star, where, in particular, the l=m=2 current quadrupole emission dominates [3]. In our earlier work [1],

Constraints from GW170817 on the bulk viscosity of neutron star matter and the r-mode instability

“…However, in the present work, the bulk viscous damping contribution is obtained from the Urca processes, which are consistent to the EOS used to compute the NS properties, as has been done by Vidaña [15] and others [66]. The gravitational and shear viscous time-scales are the same as used in our earlier work [65] and are reported in Eqs. (B.61)-(B.64) of Appendix B for the sake of completeness.…”

“…In many works [62,19], including ours in Ref. [65], a general expression for the bulk viscosity, ζ, derived from hydrodynamics was used. However, in the present work, the bulk viscous damping contribution is obtained from the Urca processes, which are consistent to the EOS used to compute the NS properties, as has been done by Vidaña [15] and others [66].…”

“…In order to have a quantitative estimate of the influence of the Urca processes on the instability boundary, we have compared the results obtained in the present work, computed using the EOS with L=70, 76.26, 80 and 90 MeV, with the calculation reported in the Ref. [65] under the minimal model (without the viscous effect from the crust-core region). In Ref.…”

“…In Ref. [65] a general expression of ζ, derived from hydrodynamical considerations (equation ( 11) of [65]), has been used. This comparison is shown in the different panels of Figures 11 and 12 for NSs of masses 1.4 M ⊙ and 1.8 M ⊙ , respectively.…”

“…The time-scale, 1/τ V E , for the viscous layer damping in the crust-core transition region is reported in Eq. ( 8) of our previous work [65] and also given in Eq. (B.65) of Appendix-B for ready reference.…”