Density and Magnetic Field Evolution

Case A: Interior and Exterior B-field (Medium Lifetime HMNS)

Here we look at the time evolution of the rest-mass density and magnetic fields.The binaries consist of identical irrotational neutron stars, each of rest-mass $M_{0}$ = 1.51 $M_{\odot}$, with total ADM mass M = 2.8 $M_{\odot}$. The rest-mass density is normalized to the maximum density at $t/M = 230$. Time is measured in $M = 1.37 \times 10^{-2} \ ms$ . The neutron stars spirals inwards, forming a hypermassive neutron star (HMNS) and a disk of matter that orbits it. Eventually the HMNS undergoes delayed collapse, and a black hole is formed. We can see that the magnetic field lines become collimated above and below the black hole, and that matter is ejected at mildly relativistic speeds. The field lines above the poles form a helical funnel which drives and confines the matter in the jet.The BH remnant has a final spin of $a_{BH}/M_{BH} \approx 0.74$.

Fig. 1-1: Density and magnetic fields	Fig. 1-2: Density and magnetic fields	Fig. 1-3: Density and magnetic fields
Fig. 1-4: Density and magnetic fields	Fig. 1-5: Density and magnetic fields	Fig. 1-6: Density and magnetic fields