scholarly journals Initial-data contribution to the error budget of gravitational waves from neutron-star binaries

2016 ◽  
Vol 94 (4) ◽  
Author(s):  
Antonios Tsokaros ◽  
Bruno C. Mundim ◽  
Filippo Galeazzi ◽  
Luciano Rezzolla ◽  
Kōji Uryū
Keyword(s):  
Neutron Star ◽  
Initial Data ◽  
Gravitational Waves ◽  
Error Budget

scholarly journals Hamiltonian charges in the asymptotically de Sitter spacetimes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Maciej Kolanowski ◽  
Jerzy Lewandowski
Keyword(s):  
Phase Space ◽  
Initial Data ◽  
Exact Solutions ◽  
Gravitational Waves ◽  
Physical Meaning ◽  
De Sitter ◽  
Killing Vectors ◽  
Asymptotically Flat ◽  
Angular Momenta ◽  
The One

Abstract We generalize a notion of ‘conserved’ charges given by Wald and Zoupas to the asymptotically de Sitter spacetimes. Surprisingly, our construction is less ambiguous than the one encountered in the asymptotically flat context. An expansion around exact solutions possessing Killing vectors provides their physical meaning. In particular, we discuss a question of how to define energy and angular momenta of gravitational waves propagating on Kottler and Carter backgrounds. We show that obtained expressions have a correct limit as Λ → 0. We also comment on the relation between this approach and the one based on the canonical phase space of initial data at ℐ+.

scholarly journals Spectral analysis of gravitational waves from binary neutron star merger remnants

2017 ◽  
Vol 96 (6) ◽  
Author(s):  
Francesco Maione ◽  
Roberto De Pietri ◽  
Alessandra Feo ◽  
Frank Löffler
Keyword(s):  
Spectral Analysis ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Binary Neutron Star

LIGO/Virgo Listens to Neutron Stars

2020 ◽  
pp. 137-145
Author(s):  
John W. Moffat
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Accurate Determination ◽  
Hubble Constant ◽  
Gravitational Theory ◽  
Optical Signal ◽  
Gravity Models ◽  
Expansion Of The Universe

On August 8, 2017, LIGO/Virgo detected the merging of two neutron stars 130 million light years away. Just 1.7 seconds later, the Fermi Gamma Ray Space Telescope received an optical signal—a short gamma ray burst (GRB). Thus began a new era of “multimessenger astronomy.” The GRBs are very energetic explosions observed in galaxies. The neutron star merger offers the first evidence that heavy metals such as gold, platinum, and uranium were created by the collision of neutron stars in a “kilonova.” The resulting gravitational waves offer a new way of measuring the Hubble constant, which determines the rate of expansion of the universe. An important result from the neutron star merger is an extremely accurate determination of the speed of gravitational waves; they move at the speed of light. This has significant ramifications for gravitational theory. It falsifies many proposed modified gravity models.

scholarly journals Plasma Damping of Gravitational Waves

1990 ◽  
Vol 142 ◽  
pp. 62-62
Author(s):  
C. Sivaram
Keyword(s):  
Neutron Star ◽  
Magnetic Fields ◽  
Gravitational Waves ◽  
Plasma Frequency ◽  
Landau Damping ◽  
Plasma Medium ◽  
Plane Gravitational Waves

The possibility of the damping of plane gravitational waves while propagating in a plasma medium is considered. The gravitational plasma frequency, is for a neutron star medium ~ 103Hz, which is the same as the frequency of the gravitational waves emitted by a collapsing star. So resonant damping of such waves within a collapsing star is probable. Estimates are made for the damping length for dense and dilute plasmas (also in the presence of magnetic fields). Analogies with Landau damping are made. Applications to other astrophysical situations are outlined.

scholarly journals Gravitational waves, neutrino emissions and effects of hyperons in binary neutron star mergers

2012 ◽  
Vol 29 (12) ◽  
pp. 124003 ◽  
Author(s):  
Kenta Kiuchi ◽  
Yuichiro Sekiguchi ◽  
Koutarou Kyutoku ◽  
Masaru Shibata
Keyword(s):  
Neutron Star ◽  
Gravitational Waves ◽  
Binary Neutron Star

scholarly journals Neutron star collapse and gravitational waves with a non-convex equation of state

2019 ◽  
Vol 484 (4) ◽  
pp. 4980-5008 ◽  
Author(s):  
Miguel A Aloy ◽  
José M Ibáñez ◽  
Nicolas Sanchis-Gual ◽  
Martin Obergaulinger ◽  
José A Font ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Waves

scholarly journals Binary Neutron Star (BNS) Merger: What We Learned from Relativistic Ejecta of GW/GRB 170817A

Physics ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 194-228 ◽  
Author(s):  
Houri Ziaeepour
Keyword(s):  
Neutron Star ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Lorentz Factor ◽  
Prompt Gamma ◽  
External Shocks ◽  
Binary Neutron Star ◽  
Tidal Forces ◽  
Relativistic Jet ◽  
Short Grbs

Gravitational Waves (GW) from coalescence of a Binary Neutron Star (BNS) and its accompanying short Gamma-Ray Burst (GRB) GW/GRB 170817A confirmed the presumed origin of these puzzling transients and opened up the way for relating properties of short GRBs to those of their progenitor stars and their surroundings. Here we review an extensive analysis of the prompt gamma-ray and late afterglows of this event. We show that a fraction of polar ejecta from the merger had been accelerated to ultra-relativistic speeds. This structured jet had an initial Lorentz factor of about 260 in our direction, which was O ( 10 ∘ ) from the jet’s axis, and was a few orders of magnitude less dense than in typical short GRBs. At the time of arrival to circum-burst material the ultra-relativistic jet had a close to Gaussian profile and a Lorentz factor ≳ 130 in its core. It had retained in some extent its internal collimation and coherence, but had extended laterally to create mildly relativistic lobes—a cocoon. Its external shocks on the far from center inhomogeneous circum-burst material and low density of colliding shells generated slowly rising afterglows, which peaked more than 100 days after the prompt gamma-ray. The circum-burst material was somehow correlated with the merger. As non-relativistic outflows or tidally ejected material during BNS merger could not have been arrived to the location of the external shocks before the relativistic jet, circum-burst material might have contained recently ejected materials from resumption of internal activities, faulting and mass loss due to deformation and breaking of stars crusts by tidal forces during latest stages of their inspiral but well before their merger. By comparing these findings with the results of relativistic Magneto-Hydro-Dynamics (MHD) simulations and observed gravitational waves we conclude that progenitor neutron stars were most probably old, had close masses and highly reduced magnetic fields.

scholarly journals Analytic properties of the electromagnetic field of binary compact stars and electromagnetic precursors to gravitational waves

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Tomoki Wada ◽  
Masaru Shibata ◽  
Kunihito Ioka
Keyword(s):  
Electromagnetic Field ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Orbital Motion ◽  
Compact Stars ◽  
Close Binary ◽  
Radio Bursts ◽  
Poynting Flux ◽  
Electromagnetic Precursors ◽  
Spiral Arm

Abstract We analytically study the properties of the electromagnetic field in the vacuum around close binary compact stars containing at least one neutron star. We show that the orbital motion of the neutron star induces high multipole modes of the electromagnetic field just before the merger. These modes are superimposed to form a spiral arm configuration, and its edge is found to be a likely site for magnetic reconnection. These modes also enhance the total Poynting flux from neutron star binaries by a factor of 2–4. We also indicate that the electric field induced by the orbital motion leads to a magnetosphere around binaries and estimate its plasma density, which has a different parameter dependence than the Goldreich–Julian density. With these properties, we discuss possible electromagnetic counterparts to gravitational wave events, and identify radio precursors, such as fast radio bursts, as the most promising observational targets.

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