EPJ A Highlight - Towards the solution of the “hyperon puzzle”

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Published on 12 December 2019

The possible presence of strange matter in the core of neutron stars has given rise to the so-called hyperon puzzle: hyperonic degrees of freedom are energetically allowed in the extreme density conditions believed to exist in the core of Neutron Stars, but hyperons reduce the internal pressure of the star, which then cannot compensate the gravitational field to sustain the most massive compact stars observed.

This work reports on the effect of three-body interactions when including a Lambda hyperon on the properties of hyper-nuclei and Neutron Stars. State-of-the-art three-body chiral effective interactions are introduced in a microscopic Brueckner-Hartree-Fock calculation.

The introduction of three-body interactions leads to an improved reproduction of hypernuclear data and stiffens the equation of state sufficiently to allow the hydrostatic equilibrium of a two-solar masses neutron star.

Even if the comparison with the observation still shows some tension, this is the first work showing without any ad-hoc adjustment of phenomenological parameters that the presence of hyperons in the core can be compatible with hyper-massive neutron stars.