On the moment of inertia of PSR J0737-3039 A from LIGO/Virgo and NICER

Zhiqiang Miao, Ang Li

Published 2021-07-16Version 1

We extend our previous study (Li et al. 2021) on neutron stars with a quark core to predict the moment of inertia of pulsar A in the double pulsar binary J0737-3039, assuming there is a phase transition in the pulsar inner core from the soft QMF or the stiff DD2 hadronic equation of state (EOS) to a high-density phase of quark matter modelled by the generic "constant-sound-speed" (CSS) parameterization. We perform a Bayesian analysis of the moment of inertia by incorporating observational data for the tidal deformability of the GW170817 and GW190425 binary neutron star mergers, as detected by LIGO/Virgo, and the mass and radius of PSR J0030+0451 and MSP J0740+6620, as detected by the Neutron Star Interior Composition Explorer. We find that the most probable values of the moment of inertia of PSR J0737-3039 A are $1.27_{-0.14}^{+0.18}\times10^{45}\,{\rm g\,cm^2}$ for QMF+CSS and similarly $1.29_{-0.15}^{+0.26}\times10^{45}\,{\rm g\,cm^2}$ for DD2+CSS at $90\%$ credible interval. We also demonstrate how a moment of inertia measurement would improve our knowledge of the EOS and the mass-radius relation for hybrid stars and discuss whether a quark deconfinement phase transition is supported by the available data and forthcoming data that could be consistent with this hypothesis.