A starquake model for Vela pulsar

Abstract

Various neutron star (NS) models correspond to an unrealistic mass range $\le 0.5M_{\odot }$ for the Vela pulsar, if the observational constraints of the glitch healing parameter in the starquake model ($Q=I_{\mathrm{core}}/I_{\mathrm{total}}\le 0.2$), are imposed on these models. However, we show that these observational constraints yield a realistic mass range for NS models, corresponding to a core given by the stiffest equations of state (EOS) and the envelope is characterized by the well known EOS of adiabatic polytrope, if the continuity of the adiabatic speed of sound together with pressure, energy-density, and the two metric parameters is assured at the core-envelope boundary of the models and this boundary is worked out on the basis of the `compatibility criterion' for hydrostatic equilibrium. The models yield the surface redshift $z_R\simeq 0.6913$ and mass $M\simeq 2.153M_{\odot }$ for the ``central'' weighted mean value, $Q=0.12\pm 0.07$, of the glitch healing parameter of the Vela pulsar. These values of mass and surface redshift can increase upto $M\simeq 2.196M_{\odot }$ and $z_R\simeq 0.7568$ (which represents an ultra-compact object (UCO; $z_R\ge 0.73$)) respectively for the upper weighted mean value of $Q\simeq 0.19$. However, for the lower weighted mean value of $Q\simeq 0.05$, the mass and surface redshift can decrease upto the values of $M\simeq 2.052M_{\odot }$ and $z_R\simeq 0.6066$ respectively. The observation of the lower bound on the energy of a $\gamma$-ray pulse at about 0.30 MeV from the Vela pulsar in 1984 is in excellent agreement with the results of this study, provided this energy could be interpreted as the energy of a gravitationally redshifted electron-positron annihilation radiation from the star's surface.

7 pages, including 2 tables and 2 figures, accepted for publication in MNRAS

References in corpus (4)

• Moments of inertia for neutron and strange stars: limits derived for the Crab pulsar
• A Comparison of Measured Crab and Vela Glitch Healing Parameters with Predictions of Neutron Star Models
• Hydrostatic equilibrium of insular, static, spherically symmetric, perfect fluid solutions in general relativity
• An upper bound on the energy of a gravitationally redshifted electron-positron annihilation line from the Crab pulsar

Cited by in corpus (3)

• Predicting the Starquakes in PSR J0537-6910
• Pi in the Sky: Neutron Stars with Exceptionally Light QCD Axions
• Analytic Core Envelope Models for the Crab and the Vela Pulsars