Was GW190814 a Black Hole-Strange Quark Star System?

Area of Science:

• Astrophysics
• Nuclear Physics
• Gravitational Wave Astronomy

Background:

• The GW190814 event detected a black hole with a low-mass companion.
• The nature of this companion is crucial for understanding compact star physics.
• Existing models struggle to explain the properties of all observed compact objects.

Purpose of the Study:

• To investigate if the GW190814 companion could be a strange quark star.
• To explore the viability of the two-families scenario for compact stars.
• To reconcile the high masses and small radii of compact objects.

Main Methods:

• Theoretical modeling of compact stars within the two-families scenario.
• Analysis of equations of state for neutron stars and strange quark stars.
• Comparison of model predictions with GW190814 observations and astrophysical constraints.

Main Results:

• Strange quark stars can achieve the mass range of the GW190814 companion (∼2.5–2.67 M☉) with a high adiabatic index.
• Neutron stars (hyperonic stars) in this scenario satisfy astrophysical and nuclear physics constraints with a softer equation of state.
• This model allows for massive stars with small radii, including radii ≤ 11 km for a 1.4 M☉ star.

Conclusions:

• The two-families scenario, where neutron stars and strange quark stars coexist, provides a consistent explanation for compact objects.
• Strange quark stars are a viable candidate for the GW190814 low-mass companion.
• This framework resolves apparent contradictions in compact star properties, such as high mass and small radius simultaneously.