Black Hole–Neutron Star Mergers as Central Engines of Gamma-Ray Bursts

Janka, Hans-Thomas; Eberl, T.; Ruffert, M.; Fryer, Chris L.

doi:10.1086/312397

Cited by 255 publications

(330 citation statements)

References 23 publications

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“…In the first one, a toroidal distribution of matter and angular momentum is placed in our computational domain, embedded by a larger, essentially spherically symmetric dilute gas cloud. Such a configuration is suggested by the previous results of and Janka et al (1999) where the gas cloud is produced by mass shed off the hot massive merger remnant. Of course, a more refined setup would require to take into account asphericities due to the angular momentum in the system.…”

Section: The Modelmentioning

confidence: 56%

“…In the angular direction, the half-opening angle of the deposition cone (θ 0 ) around the system axis spans a range which was varied between 30 • and 75 • . From the results of and Janka et al (1999) we have inferred a power-law decline for the energy deposition rate per unit of volume by νν-annihilation in the direction perpendicular to the equatorial plane of the accretion torus. We have chosen an explicit form of the energy deposition law in terms of observer frame coordinates aṡ…”

Section: Numerical Detailsmentioning

confidence: 94%

“…The situation that can arise from the mentioned merging processes consists of a central black hole of a few solar masses girded by a thick accretion torus with mass between 0.05 and ≈0.3 M (see, e.g., Janka et al 1999). Once the thick disk has formed, neutrino-antineutrino annihilation may release up to ∼10 51 erg above the poles of the black hole in a region that contains less than 10 −5 M of baryonic matter.…”

Section: The Modelmentioning

confidence: 99%

“…In this paper we present results of the first general relativistic (a fix Schwarzschild metric is assumed), axisymmetric models for the acceleration and expansion of ultrarelativistic jets and winds, which originate from the pair-plasma-photon fireball that is produced by the deposition of thermal energy above the poles of a stellar-mass BH that accretes matter from a thick accretion torus as obtained in NS+NS or NS+BH merger simulations Janka et al 1999). We use the high-resolution shock-capturing code GENESIS (Aloy et al 1999) to integrate the general relativistic hydrodynamic equations in "2.5 dimensions" (i.e., in spherical (r, θ) coordinates assuming that there is no azimuthal (φ) dependence of physical quantities although the φ-components of vectors can have non-zero values).…”

Section: Introductionmentioning

confidence: 99%

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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: The Modelmentioning

confidence: 56%

Section: Numerical Detailsmentioning

confidence: 94%

Section: The Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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show abstract

“…330-458), but there is still much that we do not understand about these exotic objects. The combination of electromagnetic observations with future detections of gravitational-wave (GW) signals will provide key insights into the nature of compact objects and the role they play in some of the most energetic events in the universe: gamma-ray bursts, active galactic nuclei, quasars, etc. (Soltan 1982;Kormendy & Richstone 1995;Magorrian et al 1998;Janka et al 1999;Gebhardt et al 2000;Hughes & Blandford 2003;Peterson et al 2004;Lee & Ramirez-Ruiz 2007;Hughes 2009;Metzger & Berger 2012;Berger 2013;Berger et al 2013;Piran et al 2013;Tanvir et al 2013). Several large-scale collaborations are working to inaugurate the new field of GW astronomy by targeting a wide variety of potential GW sources.…”

Section: Introductionmentioning

confidence: 99%

Detecting Eccentric Supermassive Black Hole Binaries With Pulsar Timing Arrays: Resolvable Source Strategies

Taylor

Huerta

Gair

et al. 2016

ApJ

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The couplings between supermassive black hole binaries (SMBHBs) and their environments within galactic nuclei have been well studied as part of the search for solutions to the final parsec problem. The scattering of stars by the binary or the interaction with a circumbinary disk may efficiently drive the system to sub-parsec separations, allowing the binary to enter a regime where the emission of gravitational waves can drive it to merger within a Hubble time. However, these interactions can also affect the orbital parameters of the binary. In particular, they may drive an increase in binary eccentricity which survives until the system's gravitational-wave (GW) signal enters the pulsar-timing array (PTA) band. Therefore, if we can measure the eccentricity from observed signals, we can potentially deduce some of the properties of the binary environment. To this end, we build on previous techniques to present a general Bayesian pipeline with which we can detect and estimate the parameters of an eccentric SMBHB system with PTAs. Additionally, we generalize the PTA  e -statistic to eccentric systems, and show that both this statistic and the Bayesian pipeline are robust when studying circular or arbitrarily eccentric systems. We explore how eccentricity influences the detection prospects of single GW sources, as well as the detection penalty incurred by employing a circular waveform template to search for eccentric signals, and conclude by identifying important avenues for future study.

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Gamma-Ray Bursts and Their Central Engines

Rosswog

2006

NATO Science Series II: Mathematics, Physics and Chemistry

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Black Hole–Neutron Star Mergers as Central Engines of Gamma-Ray Bursts

Cited by 255 publications

References 23 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

Detecting Eccentric Supermassive Black Hole Binaries With Pulsar Timing Arrays: Resolvable Source Strategies

Gamma-Ray Bursts and Their Central Engines

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