Critical phenomena in neutron stars: II. Head-on collisions

Thorsten Kellerman, Luciano Rezzolla, David Radice
2010 Classical and quantum gravity  
We consider the head-on collision of equal-mass neutron stars boosted towards each other and we study the behavior of such systems near the threshold of black-hole formation. In particular, we confirm the previous findings by [1] that a type-I critical phenomenon can be observed by fine-tuning the initial mass of the two neutron stars. At the same time, we argue against the interpretation that the critical solution is not a perturbed spherical star and show instead that the metastable star
more » ... sponds to a (perturbed) equilibrium solution on the unstable branch of the equilibrium configurations. As a result, the head-on collision of two neutron stars near the critical threshold can be seen as a transition in the space of configurations from an initial stable solution over to a critical metastable one which can either migrate to a stable solution or collapse to a black hole. The critical exponent for this process shows a fine structure which was already observed in the case of the critical collapse of scalar fields but never before for perfect fluids.
doi:10.1088/0264-9381/27/23/235016 fatcat:rnz76j5invgvpj3yocnhxpg6wa