The influence of quark matter at high densities on binary neutron star mergers

Oechslin, R.; Uryū, Kōji; Poghosyan, Gevorg; Thielemann, Friedrich‐Karl

doi:10.1111/j.1365-2966.2004.07621.x

Cited by 68 publications

(76 citation statements)

References 42 publications

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“…A high density halo would have to be expected if, for example, the collapse to a black hole were delayed due to the effects of very rapid (differential) rotation or viscous heating (e.g., Duez et al 2004;Morrison et al 2004), in which case the hot neutron star would radiate neutrinos and a neutrino-driven wind (e.g., Duncan et al 1986) would lead to a dense, expanding baryonic cloud around the merger site. It may also be possible to find situations where the accretion torus is surrounded by a thin, dilute halo, in particular, if the BH forms during the merger or within a few dynamical timescales afterwards (e.g., Shibata & Uryū 2000;Shibata et al 2003;Oechslin et al 2004). In regard of these considerations we have performed two series of simulations.…”

Section: Resultsmentioning

confidence: 99%

Relativistic outflows from remnants of compact object mergers and their viability for short gamma-ray bursts

Aloy¹,

Janka²,

Müeller³

2005

A&A

254

295

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Abstract. We present the first general relativistic hydrodynamic models of the launch and evolution of relativistic jets and winds, driven by thermal energy deposition, possibly due to neutrino-antineutrino annihilation, in the close vicinity of black hole-accretion torus systems. The latter are considered to be the remnants of compact object mergers. Our two-dimensional simulations establish the link between models of such mergers and future observations of short gamma-ray bursts by the SWIFT satellite. They show that ultrarelativistic outflow with maximum terminal Lorentz factors around 1000 develops for polar energy deposition rates above some 10 48 erg s −1 per steradian, provided the merger environment has a sufficiently low baryon density. By the interaction with the dense accretion torus the ultrarelativistic outflow with Lorentz factors Γ above 100 is collimated into a sharp-edged cone that is embedded laterally by a wind with steeply declining Lorentz factor. The typical semi-opening angles of the Γ > 100 cone are 5 • −10 • , corresponding to about 0.4−1.5% of the hemisphere and apparent isotropized energies (kinetic plus internal) up to ≈10 51 erg although at most 10−30% of the deposited energy is transferred to the outflow with Γ > 100. The viability of post-merger black hole-torus systems as engines of short, hard gamma-ray bursts is therefore confirmed. The annihilation of neutrino-antineutrino pairs radiated from the hot accretion torus appears as a suitable energy source for powerful axial outflow even if only ≈10 49 erg are deposited within a cone of 45 • half-opening angle around the system axis. Although the torus lifetimes are expected to be only between some 0.01 s and several 0.1 s, our models can explain the durations of all observed short gamma-ray bursts, because different propagation velocities of the front and rear ends will lead to a radial stretching of the ultrarelativistic fireball before transparency is reached. The ultrarelativistic flow reveals a highly non-uniform structure caused by the action of Kelvin-Helmholtz instabilities that originate at the fireball-torus interface. Large radial variations of the baryon density (up to several orders of magnitude) are uncorrelated with moderate variations of the Lorentz factor (factors of a few) and fluctuations of the gently declining radiation-dominated pressure. In the angular direction the Lorentz factor reveals a nearly flat plateau-like maximum with values of several hundreds, that can be located up to 7 • off the symmetry axis, and a steep decrease to less than 10 for polar angles larger than 15 • −20 • . Lateral expansion of the ultrarelativistic core of the flow is prevented by a subsonic velocity component of about 0.05c towards the symmetry axis, whereas the moderately relativistic wings show a subsonic sideways inflation with less than 0.07c (measured in the frame comoving with the radial flow).

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Section: Resultsmentioning

confidence: 99%

Relativistic outflows from remnants of compact object mergers and their viability for short gamma-ray bursts

Aloy¹,

Janka²,

Müeller³

2005

A&A

254

295

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“…Based on a set of simulated binary merger models [7], we identify characteristic features of the simulated GW signals and link them to the merger properties. The simulations were carried out with our relativistic smoothed particle hydrodynamics (SPH) code [10,11], which solves the relativistic hydrodynamics equations together with the Einstein field equation in the conformally flat ap- proximation [CFC; 12,13]. The simulations were started from a stable equilibrium configuration slightly outside the innermost stable circular orbit and the corresponding initial data were generated by relaxing the fluid to a velocity field that includes the orbital motion and the proper spins of the NSs.…”

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confidence: 99%

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confidence: 99%

Gravitational Waves from Relativistic Neutron-Star Mergers with Microphysical Equations of State

2007

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The gravitational wave (GW) emission from a set of relativistic neutron star (NS) merger simulations is analysed and characteristic signal features are identified. The distinct peak in the GW energy spectrum that is associated with the formation of a hypermassive merger remnant has a frequency that depends strongly on the properties of the nuclear equation of state (EoS) and on the total mass of the binary system, whereas the mass ratio and the NS spins have a weak influence. If the total mass can be determined from the inspiral chirp signal, the peak frequency of the post-merger signal is a sensitive indicator of the EoS.PACS numbers: 95.85. Sz, 97.60.Jd, 95.30.Lz Among the strongest known sources of gravitational wave (GW) emission are the merging events of double neutron star (DNS) binaries. Recent population systhesis studies (e.g. [1]) and the discovery of the DNS J0737-3039 [2] suggest a possible detection rate of GW radiation from DNS mergers of one in ∼30 years for LIGO I and one every two days for advanced LIGO. To detect such GW signals and to filter them out of the detector output, theoretical waveform templates are needed. While the inspiral phase prior to the actual merger can be described very accurately within the post-Newtonian (PN) framework (e.g. [3]), hydrodynamical simulations are needed to model the dynamical merging phase. In addition, different aspects of physics enter the problem at this stage. Besides general relativity (GR), nuclear and particle physics play a role in the description of the hot and dense NS fluid via an equation of state (EoS) and in the treatment of energy losses (e.g., by neutrinos) after the merging. The GW signal of the late inspiral and merging phases is therefore expected to contain information not only on the binary parameters such as masses and spins but also on the nuclear EoS.Efforts to investigate NS mergers have concentrated either on the relativistic aspects while simplifying the microphysics (e.g. [4] and refs. therein), or have employed a microphysical EoS together with an approximative neutrino treatment while describing gravity in a Newtonian framework (e.g., [5,6]). The conformal flatness approach, a middle ground between PN and full GR, combined with a nuclear physics-based nonzero-temperature (T = 0) EoS has recently been chosen by Oechslin et al. [7].The generic GW signal from a NS merger can be split into a chirp-like part emitted by the inspiralling binary, the burst amplitude from the final plunge when the two stars collide (when time is set to t = 0 in Fig. 1), and a quasi-periodic post-merger signal caused either by the rotation and internal oscillation of a newly formed, nonaxisymmetric hypermassive NS (HMNS) as merger remnant, or by the quasinormal ringing of a newly born black hole (BH) in case of a prompt gravitational collapse of the remnant after the final plunge. A first maximum of the compactness of the relic HMNS is associated with a minimum of the amplitude h = (|h + | 2 + |h × | 2 ) 1/2 at about 0.5 ms after the merging, followed ...

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“…Binary neutron star mergers have been simulated including a quark matter equation of state at high densities [47]. The different equations of state affect clearly the Fourier spectrum of the gravitational wave emitted.…”

Section: Gravitational Wave Signal From Strange Quark Matter?mentioning

confidence: 99%

Strange exotic states and compact stars

Sagert¹,

Wietoska²,

Schaffner-Bielich³

2006

J. Phys. G: Nucl. Part. Phys.

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Abstract. We discuss the possible appearance of strange exotic multi-quark states in the interior of neutron stars and signals for the existence of strange quark matter in the core of compact stars. We show how the in-medium properties of possible pentaquark states are constrained by pulsar mass measurements. The possibility of generating the observed large pulsar kick velocities by asymmetric emission of neutrinos from strange quark matter in magnetic fields is outlined.

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The influence of quark matter at high densities on binary neutron star mergers

Cited by 68 publications

References 42 publications

Relativistic outflows from remnants of compact object mergers and their viability for short gamma-ray bursts

Relativistic outflows from remnants of compact object mergers and their viability for short gamma-ray bursts

Gravitational Waves from Relativistic Neutron-Star Mergers with Microphysical Equations of State

Strange exotic states and compact stars

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