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arXiv · 2606.02593

Hybrid stars among mass gap objects are excluded by twin stars at $1.4\,M_\odot$

Alexander Ayriyan·David Blaschke·Marcin Dubaj·Oleksandr Vitiuk·Adrian Wojcik
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Abstract

We investigate the question whether compact objects in the so called mass gap ($2.5 < M/M_\odot < 5.0$) can be neutron stars or hybrid stars. Using a generic hybrid star equation of state with a first-order deconfinement transition, we map the allowed parameter space in a Seidov-type diagram and confront it with modern mass--radius constraints. We find that mass-gap hybrid stars require an extremely early onset of deconfinement and very stiff quark matter. The Bayesian analysis, however, favors equations of state with deconfinement at typical neutron-star masses around $1.4\,M_\odot$ with mass-twin stars that, if confirmed, would rule out hybrid stars as candidates for observed mass-gap compact objects.

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Alexander Ayriyan, David Blaschke, Marcin Dubaj, Oleksandr Vitiuk, Adrian Wojcik. 2026-05-21. Hybrid stars among mass gap objects are excluded by twin stars at $1.4\,M_\odot$. https://arxiv.org/abs/2606.02593

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