SXS studies binary neutron star binary mergers

The inspiral and merger of binaries composed of two neutron stars are excellent gravitational wave sources and strong candidate explanations for short duration gamma ray bursts.  In a series of recent papers, SXS researchers have joined the effort to model these violent events.  Nick Tacik and collaborators have been studying the usually-overlooked effect of the spins of the two neutron stars on their final orbits of inspiral.  Read the paper here (  Roland Haas, working with many on the SXS team, has carried our first binary neutron star simulation all the way through the collision of the two stars and the collapse of the giant merged neutron star into a black hole.  A paper on this simulation is still in the works, but it's already been used to test a recipe for generating binary neutron star waveforms without full numerical simulations of these events.  The paper, by Barkett et al, is here ( The idea is that binary black hole simulations are cheaper than binary neutron star simulations, and one can roughly convert the former into the latter by adding an analytic approximation of the neutron star tidal effects. Lastly, SXS researcher Francois Foucart has carried out merger simulations that study in detail what happens right after two neutron stars merge into a single more-massive neutron star.  These post-merger neutron stars ring and give off possibly-detectable gravitational waves.  Studying the post-merger mess required us to incorporate realistic nuclear physics and neutrino emission effects into simulations.  Read the paper here (

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Go, wond'rous creature!
Mount where Science guides,
Go, measure earth, weigh air,
    and state the tides;
Instruct the planets in
    what orbs to run,
Correct old Time,
    and regulate the Sun.

Alexander Pope's
An Essay on Man

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About SXS

The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.

The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.

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