Probing the Nuclear Equation of State from the Existence of a ∼2.6 M⊙ Neutron Star: The GW190814 Puzzle

On 14 August 2019, the LIGO/Virgo collaboration observed a compact object with mass similar to 2.59(-0.09)(+0.08) M-circle dot, as a component of a system where the main companion was a black hole with mass similar to 23 M-circle dot. A scientific debate initiated concerning the identification of the low mass component, as it falls into the neutron star-black hole mass gap. The understanding of the nature of GW190814 event will offer rich information concerning open issues, the speed of sound and the possible phase transition into other degrees of freedom. In the present work, we made an effort to probe the nuclear equation of state along with the GW190814 event. Firstly, we examine possible constraints on the nuclear equation of state inferred from the consideration that the low mass companion is a slow or rapidly rotating neutron star. In this case, the role of the upper bounds on the speed of sound is revealed, in connection with the dense nuclear matter properties. Secondly, we systematically study the tidal deformability of a possible high mass candidate existing as an individual star or as a component one in a binary neutron star system. As the tidal deformability and radius are quantities very sensitive on the neutron star equation of state, they are excellent counters on dense matter properties. We conjecture that similar isolated neutron stars or systems may exist in the universe and their possible future observation will shed light on the maximum neutron star mass problem.

Automated summary

This work investigates the GW190814 event observed by the LIGO/Virgo collaboration, discussing issues such as mass gap, speed of sound upper bounds, and nuclear equation of state. It highlights the importance of these studies in addressing problems related to neutron star mass and providing insights for future observations of similar isolated neutron stars or systems in the universe.