Impact of updated multipole Love numbers and f -Love universal relations in the context of binary neutron stars

Abstract

Neutron star (NS) equation of state (EoS) insensitive relations or universal relations (UR) involving neutron star bulk properties play a crucial role in gravitational-wave astronomy. Considering a wide range of equations of state originating from (i) phenomenological relativistic mean field models, (ii) realistic EoS models based on different physical motivations, and (iii) polytropic EoSs described by spectral decomposition method, we update the EoS-insensitive relations involving NS tidal deformability (Multipole Love relation) and the UR between f-mode frequency and tidal deformability (f-Love relation). We analyze the binary neutron star (BNS) event GW170817 using the frequency domain TaylorF2 waveform model with updated universal relations and find that the additional contribution of the octupolar electric tidal parameter and quadrupolar magnetic tidal parameter or the change of multipole Love relation has no significant impact on the inferred NS properties. However, adding the f-mode dynamical phase lowers the 90% upper bound on Λ by 16-20% as well as lowers the upper bound of NSs radii by ∼500m. The combined URs (multipole Love and f-Love) developed in this work predict a higher median (also a higher 90% upper bound) for Λ by 6% and also predict higher radii for the binary components of GW170817 by 200-300m compared to the URs used previously in the literature. We further perform injection and recovery studies on simulated events with different EoSs in A+ detector configuration as well as with third generation (3G) Einstein telescope. In agreement with the literature, we find that neglecting f-mode dynamical tides can significantly bias the inferred NS properties, especially for low mass NSs. However, we also find that the impact of the URs is within statistical errors.

Cost of Inferred Nuclear Parameters toward the f-mode Dynamical Tide in Binary Neutron Stars

“…We also assume a power-law prior for luminosity distance ( ) d L 2 and isotropic prior for inclination angle. For the additional parameters, such as Λ 3 , Σ 2 , and ω 2 , we use the universal relations from Pradhan et al (2023c). The remaining BNS parameters (such as sky position) are kept fixed at their injected values to reduce the computational cost.…”

“…Several investigations have been conducted to determine the impact of the dynamical tidal correction for the event GW170817 (Pratten et al 2020;Gamba & Bernuzzi 2023;Pradhan et al 2023c). Even though there is no statistically significant support (based on the Bayes factor comparison) for the inclusion of dynamical tidal corrections over adiabatic tides for the GW170817, the bias on the recovered tidal parameters cannot be disregarded (Gamba & Bernuzzi 2023;Pradhan et al 2023c). This can be explained by looking at the relatively low sensitivity of the GW detector in the region where the Note.…”

“…A significant amount of effort has been made to develop an accurate waveform model, including different corrections such as the inclusion of higherorder electric and magnetic multipolar tidal corrections (Damour & Nagar 2010;Hinderer et al 2010;Bini et al 2012;Landry & Poisson 2015;Banihashemi & Vines 2020;Henry et al 2020;Poisson 2020;Mandal et al 2024) and the dynamical tidal correction due to resonant/nonresonant excitation of NS oscillation modes (Hinderer et al 2016;Steinhoff et al 2016;Schmidt & Hinderer 2019;Gupta et al 2021Gupta et al , 2023Kuan & Kokkotas 2022;Gamba & Bernuzzi 2023;Mandal et al 2023;Abac et al 2024;Pnigouras et al 2024). Although, for the detected events GW170817 and/or GW190425, there is a minor impact on the inferred NS properties due to the additional corrections of multipolar tidal effects (Godzieba et al 2021;Narikawa 2023;Pradhan et al 2023c) or due to the consideration of the dynamical corrections (Pratten et al 2020;Gamba & Bernuzzi 2023;Pradhan et al 2023c;Abac et al 2024); their importance will be significant for future events, accessible with increasing sensitivity of the current GW detectors or even with the next-generation detectors. Furthermore, GW models, including dynamical tides, show better agreement with the numerical relativity simulations (Hinderer et al 2016;Steinhoff et al 2016;Schmidt & Hinderer 2019;Andersson & Pnigouras 2021).…”

Nuclear Physics with Gravitational Waves from Neutron Stars Disrupted by Black Holes

“…Of course, the neutron star radius can also be inferred using the tidal deformability of the neutron star, which can be measured precisely by Cosmic Explorer during the inspiral. We convert measurements of deformability Λ 2 to compactness  using the universal relations between the quadrupolar dimensionless tidal deformability and the neutron star compactness (e.g., Maselli et al 2013;Godzieba et al 2021;Keshari Pradhan et al 2022). The latter two studies fit a sixth-order polynomial for the …”

Constraining Nuclear Parameters Using Gravitational Waves from f-mode Oscillations in Neutron Stars

“…The URs have been studied in subsequent works with different assumed NS EOS models or different NS compositions (Benhar et al 2004;Sotani et al 2011;Flores et al 2017;Ranea-Sandoval et al 2018;Das et al 2021;Jaiswal & Chatterjee 2021;Pradhan & Chatterjee 2021;Aguirre 2022;Pradhan et al 2022;Ranea-Sandoval et al 2022;Zhao & Lattimer 2022;Kumar et al 2023). Though initial URs involved the compactness (M/R) and mean density of the star, later works have shown that there exists universality of mode parameters with the inertia parameter (Lau et al 2010;Chirenti et al 2015), the tidal deformability parameters (Chen & Piekarewicz 2014;Pradhan et al 2023b), and with the nuclear parameters (Sotani 2021;Kunjipurayil et al 2022), which are helpful in different scenarios in the NS asteroseismology problem. Additionally, significant effort has been put forward to investigate the impact of rotation on the QNMs and the NS asteroseismology or URs (Kastaun et al 2010;Zink et al 2010;Gaertig & Kokkotas 2011;Yoshida 2012;Doneva et al 2013;Passamonti et al 2013;Pnigouras & Kokkotas 2016;Yazadjiev et al 2017;Rosofsky et al 2019;Krüger & Kokkotas 2020a, 2020b.…”