Anisotropic mass ejection from black hole-neutron star binaries: Diversity of electromagnetic counterparts

Kyutoku, Koutarou; Ioka, Kunihito; Shibata, Masaru

doi:10.1103/physrevd.88.041503

Cited by 149 publications

(194 citation statements)

References 52 publications

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“…Note that, however, as the outflow is only mildly relativistic, even from a highly a-spherical ejecta, the emission will be roughly isotropic and viewing angle effects will be small. It is worth noting that the effect of a-sphericity is more relevant for black hole neutron star mergers, which can result in highly a-spherical mass ejection (see e.g., Kyutoku et al 2013;Foucart et al 2013). …”

Section: Numerical Resultsmentioning

confidence: 99%

Mass ejection from neutron star mergers: different components and expected radio signals

Hotokezaka

Piran

2015

Monthly Notices of the Royal Astronomical Society

132

137

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In addition to producing a strong gravitational signal, a short gamma-ray burst (GRB), and a compact remnant, neutron star mergers eject significant masses at significant kinetic energies. This mass ejection takes place via dynamical mass ejection and a GRB jet but other processes have also been suggested: a shock-breakout material, a cocoon resulting from the interaction of the jet with other ejecta, and viscous and neutrino driven winds from the central remnant or the accretion disk. The different components of the ejected masses include up to a few percent of a solar mass, some of which is ejected at relativistic velocities. The interaction of these ejecta with the surrounding interstellar medium will produce a long lasting radio flare, in a similar way to GRB afterglows or to radio supernovae. The relative strength of the different signals depends strongly on the viewing angle. An observer along the jet axis or close to it will detect a strong signal at a few dozen days from the radio afterglow (or the orphan radio afterglow) produced by the highly relativistic GRB jet. For a generic observer at larger viewing angles, the dynamical ejecta, whose contribution peaks a year or so after the event, will generally dominate. Depending on the observed frequency and the external density, other components may also give rise to a significant contribution. We also compare these estimates with the radio signature of the short GRB 130603B. The radio flare from the dynamical ejecta might be detectable with the EVLA and the LOFAR for the higher range of external densities n 0.5cm −3 .

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Section: Numerical Resultsmentioning

confidence: 99%

Mass ejection from neutron star mergers: different components and expected radio signals

Hotokezaka

Piran

2015

Monthly Notices of the Royal Astronomical Society

132

137

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“…We will study consequences of our results on the synthesis of heavy elements in the forthcoming paper. If EOS is not very soft like SFHo, some other contributions, such as mergers of black hole-neutron star binaries [38], disk winds from accretion torus around a merger remnant black hole [34,39], and magnetorotational supernova explosions [40] may be necessary. In such cases, however, it is not clear whether the universality requirement can be achieved or not.…”

Section: Summary and Discussionmentioning

confidence: 99%

Dynamical mass ejection from binary neutron star mergers: Radiation-hydrodynamics study in general relativity

et al. 2015

Self Cite

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We perform radiation-hydrodynamics simulations of binary neutron star mergers in numerical relativity on the Japanese "K" supercomputer, taking into account neutrino cooling and heating by an updated leakage-plus-transfer scheme for the first time. Neutron stars are modeled by three modern finite-temperature equations of state (EOS) developed by Hempel and his collaborators. We find that the properties of the dynamical ejecta of the merger such as total mass, average electron fraction, and thermal energy depend strongly on the EOS. Only for a soft EOS (the so-called SFHo), the ejecta mass exceeds 0.01M⊙. In this case, the distribution of the electron fraction of the ejecta becomes broad due to the shock heating during the merger. These properties are well-suited for the production of the solar-like r-process abundance. For the other stiff EOS (DD2 and TM1), for which a long-lived massive neutron star is formed after the merger, the ejecta mass is smaller than 0.01M⊙, although broad electron-fraction distributions are achieved by the positron capture and the neutrino heating.

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“…The number of simulations studying these mergers and their fates has grown with time (Rosswog et al 2004;Rosswog 2005;Rantsiou et al 2008;Foucart et al 2010Foucart et al , 2011Foucart et al , 2015Kyutoku et al 2013;Paschalidis et al 2014), all showing that the final fate of the merged system depends sensitively upon the initial conditions. Based on earlier merging BH-NS models by Rantsiou et al (2008), it was shown for one particular evolutionary model that only a fraction of BH-NS systems may potentially form an accretion torus and lead to a GRB.…”

Section: Bh-ns Mergersmentioning

confidence: 99%

“…In the past decade, the number of hydrodynamic simulations of NS-NS and BH-NS mergers has grown considerably (Foucart et al 2010(Foucart et al , 2011(Foucart et al , 2015Foucart 2012;Korobkin et al 2012;Hotokezaka et al 2013;Kyutoku et al 2013;Bauswein et al 2014;Kiuchi et al 2014;Radice et al 2014;Shibata et al 2014;Takami et al 2014). Although these models are becoming increasingly sophisticated, most of the current models include only a subset of the physics needed to model these objects: hydrodynamics, neutrino transport (or at least neutrino energy losses), nuclear equations of state, magnetic fields, and general relativity.…”

Section: Merger Modelsmentioning

confidence: 99%

The Fate of the Compact Remnant in Neutron Star Mergers

Fryer

Belczyński

Ramírez-Ruiz

et al. 2015

ApJ

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Neutron star (binary neutron star and neutron star-black hole) mergers are believed to produce short-duration gamma-ray bursts (GRBs). They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and advanced VIRGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of Newtonian merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing GRBs, LIGO/Virgo observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.

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Anisotropic mass ejection from black hole-neutron star binaries: Diversity of electromagnetic counterparts

Cited by 149 publications

References 52 publications

Mass ejection from neutron star mergers: different components and expected radio signals

Mass ejection from neutron star mergers: different components and expected radio signals

Dynamical mass ejection from binary neutron star mergers: Radiation-hydrodynamics study in general relativity

The Fate of the Compact Remnant in Neutron Star Mergers

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