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arXiv · 2112.08157

Investigating Signatures of Phase Transitions in Neutron-Star Cores

Rahul Somasundaram·Ingo Tews·Jérôme Margueron
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Abstract

Neutron stars explore matter at the highest densities in the universe such that their inner cores might undergo a phase transition from hadronic to exotic phases, e.g., quark matter. Such a transition could be associated with non-trivial structures in the density behavior of the speed of sound such as jumps and sharp peaks. Here, we employ a physics-agnostic approach to model the density dependence of the speed of sound in neutron stars and study to what extent the existence of non-trivial structures can be inferred from existing astrophysical observations of neutron stars. For this, we exhaustively study different equations of state, including as well those with explicit first-order phase transitions. We obtain a large number of different EoSs which reproduce the same astrophysical observations and obey the same physical constraints such as mechanical stability and causality. Among them, some have non-trivial structures in the sound speed while others do not. We conclude that astrophysical information to date do not require the existence of a phase transition to quark matter in the density range explored in the core of neutron stars.

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Rahul Somasundaram, Ingo Tews, Jérôme Margueron. 2021-12-15. Investigating Signatures of Phase Transitions in Neutron-Star Cores. https://doi.org/10.1103/physrevc.107.025801

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