Isospin properties in quark matter and quark stars within isospin-dependent quark mass models

We investigate the isospin properties of the strange quark matter (SQM) and quark stars (QSs) in the framework of the isospin-dependent confining quark matter (ICQM) model and confined-isospin and density-dependent mass (CIDDM) model. Within these two isospin-dependent quark mass phenomenological models, we study the quark matter symmetry energy, the stability of strange quark matter, the quark fractions, the isospin asymmetry, and the quark mass asymmetry in SQM, and the mass-radius relation of quark stars. We find that including isospin dependence of the quark mass can significantly influence the isospin properties of the quark matter. Recently, the LIGO-Virgo collaboration reported their detection of gravitational wave (GW) signals GW170817, which are originating from a binary compact star merger. Using the ICQM model and CIDDM model, we describe the compact stars with the new maximum mass limits $2.{01}_{\ensuremath{-}0.04}^{+0.04}\ensuremath{\le}M/{M}_{\ensuremath{\bigodot}}\ensuremath{\le}2.{16}_{\ensuremath{-}0.15}^{+0.17}$ as quark stars, and the dimensionless tidal deformabilities of QSs are also investigated in this work.