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arXiv · 1412.5722

Hyperon Puzzle of Neutron Stars with Skyrme Force Models

Yeunhwan Lim·Chang Ho Hyun·Kyujin Kwak·Chang-Hwan Lee
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Abstract

We consider the so called hyperon puzzle of neutron star (NS). We employ Skyrme force models for the description of in-medium nucleon-nucleon, nucleon-Lambda hyperon ($N\Lambda$), and Lambda-Lambda ($\Lambda\Lambda$) interactions. A phenomenological finite-range force for the $\Lambda\Lambda$ interaction is considered as well. Equation of state (EoS) of NS matter is obtained in the framework of density functional theory, and Tolman-Oppenheimer-Volkoff equations are solved to obtain the mass-radius relations of NSs. It has been generally known that the existence of hyperons in the NS matter is not well supported by the recent discovery of large-mass NSs ($M \simeq 2 M_\odot$) since hyperons make the EoS softer than the one without them. For the selected interaction models, $N\Lambda$ interactions reduce the maximum mass of NS by about 30~\%, while $\Lambda\Lambda$ interactions can give about 10~\% enhancement. Consequently, we find that some Skyrme force models predict the maximum mass of NS consistent with the observation of $2 M_\odot$ NSs, and at the same time satisfy observationally constrained mass-radius relations.

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Yeunhwan Lim, Chang Ho Hyun, Kyujin Kwak, Chang-Hwan Lee. 2014-12-18. Hyperon Puzzle of Neutron Stars with Skyrme Force Models. https://doi.org/10.1142/s0218301315501001

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