One-arm spiral instability in hypermassive neutron stars formed by dynamical-capture binary neutron star mergers

We consider the neutron stars mergers from the point of view of the spinar model. We present calculations of the maximum luminosity of merging neutron stars, both total and in optical ranges. The possibility of observing such gamma-ray bursts using the MASTER system of robotic telescopes is also discussed.

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Gravitational waves from remnant massive neutron stars of binary neutron star merger: Viscous hydrodynamics effects

Physical Review D ◽

10.1103/physrevd.95.123003 ◽

2017 ◽

Vol 95 (12) ◽

Cited By ~ 42

Author(s):

Masaru Shibata ◽

Kenta Kiuchi

Keyword(s):

Neutron Star ◽

Neutron Stars ◽

Gravitational Waves ◽

Binary Neutron Star ◽

Viscous Hydrodynamics

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Equation of state of dense nuclear matter and neutron star structure from nuclear chiral interactions

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731604 ◽

2018 ◽

Vol 609 ◽

pp. A128 ◽

Cited By ~ 27

Author(s):

Ignazio Bombaci ◽

Domenico Logoteta

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Neutron Stars ◽

Nuclear Matter ◽

Symmetric Nuclear Matter ◽

Heavy Nuclei ◽

Hartree Fock ◽

Binary Neutron Star ◽

Dense Nuclear Matter ◽

Three Body

Aims. We report a new microscopic equation of state (EOS) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and β-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear interactions derived in the framework of chiral perturbation theory (ChPT) and including the Δ(1232) isobar intermediate state. This EOS is provided in tabular form and in parametrized form ready for use in numerical general relativity simulations of binary neutron star merging. Here we use our new EOS for β-stable nuclear matter to compute various structural properties of non-rotating neutron stars. Methods. The EOS is derived using the Brueckner–Bethe–Goldstone quantum many-body theory in the Brueckner–Hartree–Fock approximation. Neutron star properties are next computed solving numerically the Tolman–Oppenheimer–Volkov structure equations. Results. Our EOS models are able to reproduce the empirical saturation point of symmetric nuclear matter, the symmetry energy Esym, and its slope parameter L at the empirical saturation density n0. In addition, our EOS models are compatible with experimental data from collisions between heavy nuclei at energies ranging from a few tens of MeV up to several hundreds of MeV per nucleon. These experiments provide a selective test for constraining the nuclear EOS up to ~4n0. Our EOS models are consistent with present measured neutron star masses and particularly with the mass M = 2.01 ± 0.04 M⊙ of the neutron stars in PSR J0348+0432.

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Constraints on the speed of sound of dense nuclear matter through the tidal deformability of neutron stars

EPJ Web of Conferences ◽

10.1051/epjconf/202125205005 ◽

2021 ◽

Vol 252 ◽

pp. 05005

Author(s):

Alkiviadis Kanakis-Pegios ◽

Polychronis Koliogiannis ◽

Charalampos Moustakidis

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Neutron Stars ◽

Nuclear Matter ◽

Speed Of Sound ◽

Nuclear Physics ◽

Equations Of State ◽

Open Problems ◽

Binary Neutron Star ◽

Dense Nuclear Matter

One of the greatest interest and open problems in nuclear physics is the upper limit of the speed of sound in dense nuclear matter. Neutron stars, both in isolated and binary system cases, constitute a very promising natural laboratory for studying this kind of problem. This present work is based on one of our recent study, regarding the speed of sound and possible constraints that we can obtain from neutron stars. To be more speciﬁc, in the core of our study lies the examination of the speed of sound through the measured tidal deformability of a binary neutron star system (during the inspiral phase). The relation between the maximum neutron star mass scenario and the possible upper bound on the speed of sound is investigated. The approach that we used follows the contradiction between the recent observations of binary neutron star systems, in which the effective tidal deformability favors softer equations of state, while the high measured masses of isolated neutron stars favor stiffer equations of state. In our approach, we parametrized the stiffness of the equation of state by using the speed of sound. Moreover, we used the two recent observations of binary neutron star mergers from LIGO/VIRGO, so that we can impose robust constraints on the speed of sound. Furthermore, we postulate the kind of future measurements that could be helpful by imposing more stringent constraints on the equation of state.

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Pan Galactic Gargle Blaster

The Cosmic Mystery Tour ◽

10.1093/oso/9780198831860.003.0017 ◽

2019 ◽

pp. 132-137

Author(s):

Nicholas Mee

Keyword(s):

General Relativity ◽

Neutron Star ◽

Neutron Stars ◽

Gravitational Waves ◽

Gamma Ray ◽

Great Accuracy ◽

Gamma Ray Bursts ◽

Tests Of General Relativity ◽

Binary Neutron Star

The sources of short gamma ray bursts (GRBs) have been identified with neutron star merger events. Hulse and Taylor discovered the first binary neutron star in 1974. By monitoring the pulsar in this system the orbital characteristics of the system have been determined with great accuracy. This has led to tests of general relativity, including the first confirmation of the existence of gravitational waves. The emission of this radiation is gradually bringing the two neutron stars together. They will collide and merge in about 300 million years.

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Speed of sound and quark confinement inside neutron stars

The European Physical Journal Special Topics ◽

10.1140/epjst/e2020-000093-3 ◽

2020 ◽

Vol 229 (22-23) ◽

pp. 3651-3661

Author(s):

Michał Marczenko

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Neutron Stars ◽

Speed Of Sound ◽

Dense Matter ◽

High Mass ◽

Quark Confinement ◽

Binary Neutron Star ◽

Upper Limit ◽

Unified Description

AbstractSeveral observations of high-mass neutron stars (NSs), as well as the first historic detection of the binary neutron star merger GW170817, have delivered stringent constraints on the equation of state (EoS) of cold and dense matter. Recent studies suggest that, in order to simultaneously accommodate a 2M⊙ NS and the upper limit on the compactness, the pressure has to swiftly increase with density and the corresponding speed of sound likely exceeds the conformal limit. In this work, we employ a unified description of hadron-quark matter, the hybrid quark-meson-nucleon (QMN) model, to investigate the EoS under NS conditions. We show that the dynamical confining mechanism of the model plays an important role in explaining the observed properties of NSs.

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