Simulations of rotating neutron star collapse with the puncture gauge: End state and gravitational waveforms

Abstract

We reexamine the gravitational collapse of rotating neutron stars to black holes by new 3 þ 1 numerical relativity simulations employing the Z4c formulation of Einstein equations, the moving puncture gauge conditions, and a conservative mesh refinement scheme for the general relativistic hydrodynamics. The end state of the collapse is compared to the vacuum spacetime resulting from the evolution of spinning puncture initial data. Using a local analysis for the metric fields, we demonstrate that the two spacetimes actually agree. Gravitational waveforms are analyzed in some detail. We connect the emission of radiation to the collapse dynamics using simplified spacetime diagrams, and discuss the similarity of the waveform structure with the one of black hole perturbation theory.

Simulations of inspiraling and merging double neutron stars using the Spectral Einstein Code

“…See Figure 15 for visualization of the (2,0)-mode of Ψ 4 for the D4 case. In addition to our results, we present the waveform of [139] for the same case. As for the comparison of the NSNS waveform in Sec.…”

“…. We show different resolutions and compare our waveform with the published results of [139]. The BAM waveform of [139] is shifted in time such that amplitude maxima coincide.…”

“…Here, we perturb the NS according to the discussion in Appendix B 1 and set f d = 0.9 for a pressure depletion of 10%. In [139], the pressure is simply decreased by 0.5%. .…”

“…IV C, Ref. [139] uses the BAM code. The extraction radii are slightly different between the waveforms, while our waveforms are extracted at a fixed coordinate radius of r = 259M , the BAM waveform is extracted at r = 250M .…”

All-sky search for long-duration gravitational wave transients with initial LIGO

“…GW emission may eventually terminate when the neutron star collapses to a black hole. The collapse process and formation of the black hole itself will also produce a shortduration GW burst [53][54][55].…”