Strange Stars with Dark Matter Core Could Explain Astrophysical Observations, Study Suggests

Scientists have proposed the existence of Color-Flavor Locked (CFL) strange stars made of strange quark matter (SQM), which could be the true ground state of baryonic matter. The central compact object within the supernova remnant HESS J1731347 could be a strange star, given its mass and high temperature. The study also suggests these stars may contain a mirror dark matter (MDM) core. This theory could explain observations of the HESS J1731347 and other compact objects without the need for an extremely large pairing gap. The findings could enhance understanding of strange stars and the role of dark matter within them.

What are Color-Flavor Locked Strange Stars with a Mirror Dark Matter Core?

Color-flavor locked (CFL) strange stars are a type of star hypothesized to exist in the universe. These stars are made of strange quark matter (SQM), which consists of up, down, and strange quarks and electrons. The existence of these stars is a consequence of the hypothesis that SQM may be the true ground state of baryonic matter. At sufficiently high density, quarks of different color and flavor form Cooper pairs with the same Fermi momentum and the ground state of quantum chromodynamics with three flavors is the color-flavor locked (CFL) phase. Thus, strange stars might be made of SQM in the CFL phase.

The mass of the central compact object within the supernova remnant HESS J1731347 is measured to be M 0.77±0.20 M, which implies that it could be a strange star rather than a neutron star (NS), since it is less than 1.17M, which is suggested to be the minimum mass of an NS within the supernova remnant. The HESS J1731347 compact object might be a strange star in the CFL phase considering its high temperature.

What is the Role of Mirror Dark Matter in CFL Strange Stars?

In this paper, the researchers propose an explanation to all of the abovementioned astrophysical observations which supposes that these compact stars are strange stars in the CFL phase and assumes that a mirror dark matter (MDM) core exists in the CFL strange stars in GW170817 event. They show that in this scenario, the observations of the central compact object within the supernova remnant HESS J1731347 and the compact objects in GW190814 and GW170817 events could be explained simultaneously without the use of the extremely large pairing gap 200 MeV. More importantly, they find that the conformal bound or the positive trace anomaly bound could be satisfied.

Compact stars might contain a dark matter core made of self-interacting dark matter. Neutron stars and strange stars with a dark matter core have been studied extensively, and the case of a MDM core has also been studied. Technically, this study is an extension of an earlier paper in which strange stars made of unpaired SQM with a MDM core are investigated.

How is the Equation of State of the CFL SQM and MDM Determined?

For unpaired SQM, the grand canonical potential per unit volume can be written as a function of the grand canonical potential for uds quarks and electrons described as ideal relativistic Fermi gases. In the calculation, the strange quark mass is chosen to be ms 93MeV, while the masses of the up and down quarks and electrons are set to be zero. The second term at the right hand side of the equation accounts for the perturbative quantum chromodynamics (QCD) corrections due to gluon mediated quark interactions to Oα2s. The quartic coefficient a4 represents the degree of quark interaction correction in perturbative QCD and a4 = 1 corresponds to no QCD corrections.

What are the Implications of the Study?

The study of the structure and the tidal deformability of the CFL strange stars with a MDM core and the explanation of the mass and radius of the HESS J1731347 compact object, the mass of GW190814’s secondary component, and the tidal deformability of GW170817 simultaneously are significant contributions to the field of astrophysics. The findings of this study could lead to a better understanding of the nature of strange stars and the role of dark matter in these celestial bodies.

What are the Future Directions of the Study?

The researchers plan to continue their investigation of the structure and the tidal deformability of the CFL strange stars with a MDM core. They aim to further explain the mass and radius of the HESS J1731347 compact object, the mass of GW190814’s secondary component, and the tidal deformability of GW170817 simultaneously. The researchers also aim to further explore the implications of their findings on the nature of strange stars and the role of dark matter in these celestial bodies.