Tidal dissipation in binary neutron star inspirals from hyperon bulk viscosity: Phase modeling and parameter estimation bias

TL;DR

We address tidal dissipation from hyperon bulk viscosity in binary neutron star inspirals and its imprint on gravitational-wave phase. We compute the dissipated energy using a Newtonian mode-sum framework and convert it to a frequency-domain phase correction with a stationary-phase approximation, parameterized by a four-parameter function $\Delta\Phi(v)$. Injection-recovery analyses with third-generation detectors show that ignoring this heating can bias the inferred tidal deformability, especially for high-mass (≈$2M_\odot$) binaries, where heating can dominate the phase. Including the heating model allows accurate recovery of $\tilde{\Lambda}$ and the associated phase, illustrating how tidal dissipation can serve as a probe of hyperon-rich dense matter and motivating relativistic improvements. The results highlight the potential of gravitational-wave observations to constrain exotic matter in neutron-star interiors and define a path toward a relativistic, microphysically grounded treatment of tidal dissipation in waveform models.

Abstract

During the inspiral of a binary neutron star, viscous processes in the neutron star matter can damp out the tidal energy induced by its companion and convert it to thermal energy. This tidal dissipation/heating process introduces a net phase shift in the gravitational wave signal. In our recent work, we showed based on a Newtonian estimate that tidal dissipation from bulk viscosity originating from the non-leptonic weak interactions involving hyperons could have a detectable phase shift in the gravitational-wave (GW) signal in the next-generation GW detectors. Using simulated signals, we demonstrate that not accounting for this physical effect in waveform models can result in systematic biases in tidal deformability measurements of high-mass neutron star ($\geq 1.8M_{\odot}$) binary observations in next-generation GW detectors. By employing Newtonian orbital dynamics, we model this tidal dissipation induced dephasing as a phenomenological function of the characteristic velocity. We incorporate its effect in gravitational waveforms of equal-mass binary neutron stars. Those waveforms are used to perform a full Bayesian parameter estimation, which confirms that our model can alleviate possible biases in tidal deformability estimation. We also illustrate that the model can accurately measure the additional phase due to tidal dissipation in a $2M_{\odot}$ neutron star in observations with next-generation GW detectors and discuss its significance in extreme matter studies.

Figures (8)

• Figure 1: Bulk viscous dissipation rate of hyperonic neutron stars as a function of their characteristic velocity in gravitational-wave binaries. Equal-mass BNS systems are considered here, with the legend reporting the total mass for each of the binaries. The black squares represent the individual maxima.
• Figure 2: Estimated phase due to tidal deformability (dotted lines) and tidal heating (solid lines) as a function of $v = (\pi Mf)^{1/3}$ for equal mass binary of $1.6, 1.8$ and $2.0 M_{\odot}$ individual masses.
• Figure 3: Injection and recovery of effective tidal deformability from BNS event with ET-D sensitivity of equal masses for three different EOSs: a) HZTCS(upper panel) b)FSU2(middle panel) and c)Nl3(lower panel). Blue and orange posteriors show injection without(TF2) and with effects of tidal heating(Heated) respectively. Recovery is always done with the TF2 model. Black line shows the injected value.
• Figure 4: Injection and recovery of effective tidal deformability from single BNS event at 150 Mpc distance with CE sensitivity of equal masses for three different EOSs: a) HTZCS(upper panel) b) FSU2( middle panel) and c)NL3 (lower panel). Blue and orange posteriors show injection without (TF2) and with effects of tidal heating (Heated) respectively. Recovery is always done with the TF2 model. Black line shows the injected value.
• Figure 5: Model of the frequency-domain dephasing due to tidal heating for three different total mass values. The solid curves show the dephasing obtained by numerically integrating Eq. \ref{['psi']}, and the individual fits with the ansatz in Eq. \ref{['eq:ansatz']} are shown by the black dashed curves.