Quark star matter at finite temperature

We have investigated the properties of strange quark matter and quark stars at finite temperature within the confined isospin-density-dependent mass (CIDDM) model. The newly discovered heavy compact stars PSR $\mathrm{J}0348+0432$ ($2.01\pm 0.04M_{\odot }$) and MSP $\mathrm{J}0740+6620$ ($2.14{\pm }_{0.09}^{0.10}{M}_{\odot }$ of 68.3% credibility interval and $2.14{\pm }_{0.18}^{0.20}{M}_{\odot }$ of 95.4% credibility interval) can be well described as quark stars with large quark matter symmetry energy within the CIDDM model in this work. In particular, we also calculate the properties of the protoquark stars (PQSs) at the heating and cooling stages along the star evolution line, and we find that the tidal deformability of PQSs increases with temperature in the heating stages within the CIDDM model.

Figure 1

Two-flavor $u\text{−}d$ quark matter symmetry energy as functions of temperature within the CIDDM model using different DI, when the baryon density is $1{\mathrm{fm}}^{-3}$.

Figure 2

Maximum mass for quark stars using DI-85 and DI-245 at different temperatures within the CIDDM model.

Figure 3

${\mathrm{\Lambda }}_{1.4}$ as functions of the temperature with different $D_I$ in the CIDDM model.

Figure 4

Maximum mass of PQS as functions of the radius at three snapshots along star evolution within the CIDDM model with DI-85 and DI-245. The shaded band represents the pulsar mass of $2.01\pm 0.04M_{\odot }$ from PSR $\mathrm{J}0438+0432$ and the pulsar mass of $2.14{\pm }_{0.18}^{0.20}{M}_{\odot }$ from PSR $\mathrm{J}0740+6620$.