Probing the Incompressibility of Nuclear Matter at Ultrahigh Density through the Prompt Collapse of Asymmetric Neutron Star Binaries

Perego, Albino; Logoteta, Domenico; Radice, David; Bernuzzi, Sebastiano; Kashyap, R.; Das, Abhishek; Surendra, Padamata,; Prakash, Aviral

doi:10.1103/physrevlett.129.032701

“…Thus, asymmetric mergers can be electromagnetically bright because they produce massive tidal dynamical ejecta and remnants with accretion discs of mass ∼0.1 M . This prompt collapse process is mainly controlled by the incompressibility parameter of nuclear matter around the TOV maximum density [139]. A robust, EOS-insensitive criterion is not known in these These data are not released in the database since the waveforms are rather short and extracted at close radii.…”

Section: Overviewmentioning

confidence: 99%

“…conditions [56,[139][140][141][142], but tidal disruption effects are subdominant to the mass effect; they produce maximal variations from the equal-mass criterion of ∼8% [138,139].…”

Section: Overviewmentioning

confidence: 99%

Second release of the CoRe database of binary neutron star merger waveforms

González¹,

Zappa²,

Breschi³

et al. 2022

Preprint

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We present the second data release of gravitational waveforms from binary neutron star merger simulations performed by the Computational Relativity (CoRe) collaboration. The current database consists of 254 different binary neutron star configurations and a total of 590 individual numerical-relativity simulations using various grid resolutions. The released waveform data contain the strain and the Weyl curvature multipoles up to = m = 4. They span a significant portion of the mass, mass-ratio, spin and eccentricity parameter space and include targeted configurations to the events GW170817 and GW190425. CoRe simulations are performed with 18 different equations of state, seven of which are finite temperature models, and three of which account for non-hadronic degrees of freedom. About half of the released data

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“…To date, post-merger GWs from BNS mergers have not been detected, but the Einstein Telescope and the Cosmic Explorer should reach the required sensitivity and largely increase the probability of detecting these signals. Such a discovery would strongly impact our knowledge of the nuclear EOS at high densities, even at a finite temperature (Sekiguchi et al 2011b;Bauswein et al 2012;Takami et al 2014;Weih et al 2020;Perego et al 2022;Breschi et al 2022), which is still quite uncertain. In this context, precise numerical simulations based on accurate modelling of the merger microphysics are mandatory.…”

Section: Introductionmentioning

confidence: 99%

Muons in the aftermath of neutron star mergers and their impact on trapped neutrinos

Loffredo

¹

,

Perego

²

,

Logoteta

³

et al. 2023

A&A

Self Cite

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Context. In the upcoming years, present and next-generation gravitational wave observatories will detect a larger number of binary neutron star (BNS) mergers with increasing accuracy. In this context, improving BNS merger numerical simulations is crucial to correctly interpret the data and constrain the equation of state (EOS) of neutron stars (NSs). Aims. State-of-the-art simulations of BNS mergers do not include muons. However, muons are known to be relevant in the microphysics of cold NSs and are expected to have a significant role in mergers, where the typical thermodynamic conditions favour their production. Our work is aimed at investigating the impact of muons on the merger remnant. Methods. We post-process the outcome of four numerical relativity simulations of BNS mergers performed with three different baryonic EOSs and two mass ratios considering the first 15 milliseconds after merger. We compute the abundance of muons in the remnant and analyse how muons affect the trapped neutrino component and the fluid pressure. Results. We find that depending on the baryonic EOS, the net fraction of muons is between 30% and 70% the net fraction of electrons. Muons change the flavour hierarchy of trapped (anti-)neutrinos such that deep inside the remnant, muon anti-neutrinos are the most abundant, followed by electron anti-neutrinos. Finally, muons and trapped neutrinos modify the neutron-to-proton ratio, affecting the remnant pressure by up to 7% when compared with calculations neglecting them. Conclusions. This work demonstrates that muons have a non-negligible effect on the outcome of BNS merger simulations, and they should be included to improve the accuracy of a simulation.

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“…Finding the EOS of the densest visible matter in the universe is an ultimate goal of astrophysics in the era of high-precision multimessenger astronomy (Sathyaprakash et al 2019). However, despite much effort in using various data and models over the last few decades, information about the NS core EOS remains elusive and ambiguous (De et al 2018;Radice et al 2018;Tews et al 2018;Bauswein et al 2019;Baym et al 2019;Montaña et al 2019;Most et al 2019;Xie & Li 2019, 2021Zhang & Li 2019a, 2019b, 2021Drischler et al 2020;Weih et al 2020;Zhao & Lattimer 2020;Miao et al 2021;Pang et al 2021;Raaijmakers et al 2021;Tan et al 2022aTan et al , 2022bBreschi et al 2022;Huth et al 2022;Perego et al 2022), partially because of the strong degeneracy between the core EOSs and the still poorly understood crust. Can one directly extract the core EOS from some NS observables without using any specific model EOS?…”

Section: Introductionmentioning

confidence: 99%

Core States of Neutron Stars from Anatomizing Their Scaled Structure Equations

Cai¹,

Li

²

,

Zhang³

2023

ApJ

5

0

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Given an Equation of State (EOS) for neutron star (NS) matter, there is a unique mass–radius sequence characterized by a maximum mass M NS max at radius R max. We first show analytically that the M NS max and R max scale linearly with two different combinations of the NS central pressure P c and energy density ε c, by dissecting perturbatively the dimensionless Tolman–Oppenheimer–Volkoff (TOV) equations governing NS internal variables. The scaling relations are then verified via 87 widely used and rather diverse phenomenological as well as 17 microscopic NS EOSs with/without considering hadron–quark phase transitions and hyperons, by solving numerically the original TOV equations. The EOS of the densest NS matter allowed before it collapses into a black hole is then obtained. Using the universal M NS max and R max scalings and Neutron Star Interior Composition Explorer and XMM-Newton mass–radius observational data for PSR J0740+6620, a very narrow constraining band on the NS central EOS is extracted directly from the data for the first time, without using any specific input EOS model.

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Probing the Incompressibility of Nuclear Matter at Ultrahigh Density through the Prompt Collapse of Asymmetric Neutron Star Binaries

Cited by 23 publications

References 110 publications

Second release of the CoRe database of binary neutron star merger waveforms

Second release of the CoRe database of binary neutron star merger waveforms

Muons in the aftermath of neutron star mergers and their impact on trapped neutrinos

Core States of Neutron Stars from Anatomizing Their Scaled Structure Equations

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