Mechanism for Gammaray Bursts (computer sim shows neutron star merger works)

In summary, the study shows that the merger of magnetized neutron stars can result in a rapidly spinning black hole surrounded by a hot and highly magnetized torus, which can potentially launch a relativistic jet and explain the nature of Short Gamma-Ray Bursts (SGRBs). The simulations also demonstrate that the effective-one-body (EOB) analytical model can accurately reproduce the numerical waveforms of the inspiral of binary neutron stars, providing important information about the equation of state of matter at nuclear density.
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http://arxiv.org/abs/1101.4298
The missing link: Merging neutron stars naturally produce jet-like structures and can power short Gamma-Ray Bursts
Luciano Rezzolla, Bruno Giacomazzo, Luca Baiotti, Jonathan Granot, Chryssa Kouveliotou, Miguel A. Aloy
(Submitted on 22 Jan 2011)
"Short Gamma-Ray Bursts (SGRBs) are among the most luminous explosions in the universe, releasing in less than one second the energy emitted by our Galaxy over one year. Despite decades of observations, the nature of their "central-engine" remains unknown. Considering a binary of magnetized neutron stars and solving Einstein equations, we show that their merger results in a rapidly spinning black hole surrounded by a hot and highly magnetized torus. Lasting over 35 ms and much longer than previous simulations, our study reveals that magnetohydrodynamical instabilities amplify an initially turbulent magnetic field of ~ 1012 G to produce an ordered poloidal field of ~ 1015 G along the black-hole spin-axis, within a half-opening angle of ~ 30 deg, which may naturally launch a relativistic jet. The broad consistency of our ab-initio calculations with SGRB observations shows that the merger of magnetized neutron stars can provide the basic physical conditions for the central-engine of SGRBs."

Published version in ApJL; for high-resolution images and animations see this webpage:
http://numrel.aei.mpg.de/images/relativistic-binary-neutron-star-inspirals

see also this Science Daily article:
http://www.sciencedaily.com/releases/2011/04/110407132618.htm

Also this followup article by some of the same AEI authors:
http://arxiv.org/abs/1103.3874
Accurate numerical simulations of inspiralling binary neutron stars and their comparison with effective-one-body analytical models
Luca Baiotti, Thibault Damour, Bruno Giacomazzo, Alessandro Nagar, Luciano Rezzolla
25 pages, 16 figs
(Submitted on 20 Mar 2011)
"Binary neutron-star systems represent one of the most promising sources of gravitational waves. In order to be able to extract important information, notably about the equation of state of matter at nuclear density, it is necessary to have in hands an accurate analytical model of the expected waveforms. Following our recent work, we here analyze more in detail two general-relativistic simulations spanning about 20 gravitational-wave cycles of the inspiral of equal-mass binary neutron stars with different compactnesses, and compare them with a tidal extension of the effective-one-body (EOB) analytical model. The latter tidally extended EOB model is analytically complete up to the 1.5 post-Newtonian level, and contains an analytically undetermined parameter representing a higher-order amplification of tidal effects. We find that, by calibrating this single parameter, the EOB model can reproduce, within the numerical error, the two numerical waveforms essentially up to the merger. By contrast, analytical models (either EOB, or Taylor-T4) that do not incorporate such a higher-order amplification of tidal effects, build a dephasing with respect to the numerical waveforms of several radians."
 
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Huh, that's pretty cool. :biggrin:
 

Related to Mechanism for Gammaray Bursts (computer sim shows neutron star merger works)

1. What is a Gammaray Burst (GRB)?

A Gammaray Burst (GRB) is a highly energetic explosion that releases a massive amount of gamma rays, the most energetic form of electromagnetic radiation. These bursts can last from a few milliseconds to several minutes and can emit as much energy as our Sun does in its entire lifetime.

2. How are GRBs formed?

GRBs are believed to be caused by the merging of two neutron stars or a neutron star and a black hole. As these incredibly dense objects spiral towards each other, they release an enormous amount of energy in the form of gamma rays.

3. What is the mechanism behind GRBs?

The exact mechanism behind GRBs is still not fully understood, but scientists have proposed two potential mechanisms: the collapsar model and the merger model. In the collapsar model, a massive star collapses into a black hole, which then produces a jet of gamma rays. In the merger model, two neutron stars or a neutron star and a black hole merge, producing a short burst of gamma rays.

4. How do computer simulations show that the merger of neutron stars can produce GRBs?

Computer simulations use sophisticated models and algorithms to simulate the merging of two neutron stars and the resulting emission of gamma rays. These simulations take into account various factors such as the mass and spin of the neutron stars, the strength of the magnetic fields, and the physics of the merger process to accurately predict the production of GRBs.

5. Why is understanding the mechanism for GRBs important?

GRBs are some of the most energetic events in the universe and studying them can provide valuable insights into the physics behind extreme environments. Additionally, understanding the mechanism for GRBs can help us better understand the formation and evolution of neutron stars and black holes, as well as the processes that drive the growth of galaxies.

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