Thermal Evolution Of Strange Stars With A Crust

Strange star (SS) is a star composed of strange quark matter, possibly, with a normal nuclear crust due to the strong electric field on the surface of the quark core. The research of the thermal evolution of SSs is of significant importance for understanding the properties of this mysterious object.Considering the effects of the existence of the crust on the thermal evolution, I firstly discussed two relevant issues, (i) Analyzing the mechanical equilibrium of the crust qualitatively, I reckon that it is the degenerate pressure of electrons in the electrosphere to support the crust, but not the electric force (means that there is no electric field in the base of the crust), (ii) The effect of a strong magnetic field on the electrosphere is investigated, which enhances the intensity of the electric field and decreases the gap width between the quark core and the crust. Thus I reckon that strange magnetar (B > 10¹⁶G) could be bare. In addition, the effect of the magnetic field on the thermal evolution by changing the thermal structure of the crust directly is also studied. Under this influence, the temperature in the neutrino cooling stage is increased and the photon cooling effect is advanced. However, the effect of a weaker (B < 10¹³G) magnetic field can be neglected.Recently, phenomenological and microscopic studies have confirmed that strange quark matter at a sufficiently high density, as in compact stars, undergoes a phase transition into a color superconducting state, which can change the properties of the matter, such as the neutrino emissivity, the specific heat and the viscosity. Especially, in a SS in the CFL phase (CSS), the neutrino emission and quark specific heat are almost switched off totally. Based on the consideration of coupling of the rotational and thermal evolution, I research two kinds of heating mechanisms induced by the spin-down of the star: crust deconfinement heating and r-mode dissipation heating. Under these heating effects, the cooling of SSs is delayed considerably, even is replaced by a rise of temperature at the first ages.In particular, the heating effects change the thermal evolution of CSSs totally, which becomes to a very slow progress from a extremely rapid cooling. Thus the understanding that CSSs are in strong contradiction with the X-ray data is changed. Reversely, an older ( 10⁶yr) CSS can have a high temperature. Furthermore, a theoretical limit temperature line of compact stars is given by CSSs with deconfinement heating. In addition, the combination of the r-mode and thermal evolution results in that a CSS can retain at the bottom of its instability window for a long term, but not only several hours as estimated previously. This change is favorable for understanding the clustering of the millisecond pulsars and probing...