Electrically charged supermassive twin stars

Abstract

By assuming that ultra dense hybrid neutron stars are endowed with a distribution of electric charge, we study the corresponding twin star solutions and their properties resulting from a sharp first order transition from confined hadronic to a deconfined quark phase. Two distinct quark matter equations of state with increasing stiffness are considered and the values for the maximum gravitational masses of the hadronic and hybrid twin configurations are obtained for different values of the total electric charge. Interestingly, our calculations indicate that sharp transitions make charged twin hybrid stars more massive than their neutral counterparts, and that the $${2}\,{\hbox {M}_{\odot }}$$ 2 M ⊙ constraint from PSR J0740+6620 is surpassed for standard values of electric charge and can be considered stable only satisfying $$\partial M/\partial \epsilon _0 > 0$$ ∂ M / ∂ ϵ 0 > 0 . In particular, our charged stellar models reach masses even higher than the unknown compact object measured in the GW190814 event.

Confirming the Existence of Twin Stars in a NICER Way

“…A first-order phase transition can generate so-called "twin stars" in the mass-radius relation, which are compact stars with identical masses, but different radii (Kämpfer 1981;Glendenning & Kettner 2000;Schertler et al 2000;Schaffner-Bielich et al 2002;Zdunik & Haensel 2013;Alford et al 2015;Blaschke & Alvarez-Castillo 2016;Zacchi et al 2017;Christian et al 2018;Goncalves et al 2022). It can be convenient to analyze these twin star configurations in terms of four distinct categories, as we outlined in Christian et al (2018).…”

Electrically charged strange stars with an interacting quark matter equation of state

“…In addition to the EOS, the presence of electric charge inside the star can change its structural properties [24][25][26][27]. In general, neutrons stars, such as SQSs, are assumed to be electrically neutral.…”

Fundamental-mode eigenfrequencies of neutral and charged twin neutron stars

“…∂ M/∂ p c ≥ 0, is enough to determine the stability of hybrid stars. On the other hand, when the conversion time is much larger than that of the oscillation (slow conversions), such criterion has been shown to be insufficient to determine the stability of hybrid stars with one or two sharp phase transitions [35,[38][39][40].…”

“…In addition, and as already briefly discussed, in recent years several studies have analyzed the impact of electric charge distribution on the structure properties of compact stars [41][42][43][44][45][46][47]. In principle, apart from mass accretion, a compact star could also be electrically charged after the merger of two NSs if the remnant is stable.…”

“…In particular, in Ref. [47], we have shown that charged twin hybrid stars are more massive than their neutral counterparts, with the presence of electric charge diminishing the stability region but generating stable configurations with large masses ( 2.2M ), in agreement with recent measurements of heavy NS masses [48][49][50]. More interestingly, for some amounts of electric charge the stellar masses even surpass the 2.5M limit put by the unknown object detected by the GW190814 event [51].…”