Hybrid stars may have an inverted structure

Abstract

We propose a new stellar structure of compact stars, the ``cross stars" that consist of a hadronic matter core and a quark matter crust, with an inverted structure compared to the conventional hybrid stars. This distinct stellar structure naturally arises from the quark matter to hadronic matter transition associated with the chemical potential crossing, in the context of the quark matter hypothesis that either strange or up-down quark matter is the ground state of baryonic matter at low pressure. We find that the interplay between the hadronic matter and quark matter compositions of cross stars can help to reconcile the small radii constraints indicated by the LIGO/Virgo GW170817 event, the large radii constraints set for massive compact stars by recent NICER X-ray observations, and the recent observation of the most-massive pulsar PSR J0952-0607. This leaves more space open for the equation of states of both hadronic matter and quark matter.

10 pages, 6 figures. Published version. Typo fixed

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Cited by in corpus (7)

• Hybrid Strangeon Stars
• Radial and Non-Radial Oscillations of Inverted Hybrid Stars
• Universal relations for anisotropic interacting quark stars
• Observational Probes of the Neutron Star Equation of State with Hyperons, Bosonic Dark Matter, and Quark Matter
• Confronting recent light compact star observations with color-flavor locked quark matter
• Rotational Properties of Inverted Hybrid Stars
• Constraining the competition between the deconfinement and chiral phase transitions in light of the multimessenger era