Italian researchers at the University of Pisa, the University of Ferrara and the National Institute of Nuclear Physics (INFN) have suggested that the source of the GW190814 gravitational waves detected Aug. 14, 2019, by the LIGO Collaboration is a binary system that includes a hypothetical quark star. A summary of the study, published in the journal Physical Review Letters.
According to the model proposed by the authors of the scientific paper, a quark star forms when a number of conditions are met. First, the density of the bowels must be high enough to make the transition from normal nuclear matter (consisting of protons and neutrons) to a liquid of three quarks (top, bottom and strange). Second, if the “strange quark matter” is absolutely stable, then the normal neutron stars, whose mass exceeds the threshold value, become metastable and transform into strange quark stars.
The astrophysical scenario assumes that there are two coexisting families of compact stars in nature, namely, normal neutron stars and strange quark stars. Moreover, when a neutron star turns into a strange quark star, it emits a significant amount of energy (about 10 in the 53rd degree of erg), which resembles a supernova explosion. Quark matter is very hard, and such stars can hold the mass of three suns.
Analysis of the GW190814 data showed that the mass of the second compact object serves as an indication of the presence of a quark star in the system. In general, the event could be the result of the merger of two neutron stars, a neutron star and a quark star, or two quark stars. Further observations will help verify the hypothesis of the Italian researchers.