Rotating Hybrid Stars with Color-Flavor-Locked Quark Matter

TL;DR

This study models rotating hybrid stars with CFL quark matter, analyzing their structural properties and stability under various astrophysical constraints, and explores how phase transitions affect their characteristics.

Contribution

It presents a detailed analysis of hybrid star models with CFL quark matter, incorporating phase transitions and rotational effects, and compares results with multiple astrophysical observations.

Findings

Hybrid stars satisfy observational constraints from GW and NICER data.

Phase transition causes instability at certain densities.

Rotating star models meet constraints from fast pulsars and maximum mass observations.

Abstract

In the present work we have achieved phase transition from $\beta$ stable hadronic matter to color-flavor locked (CFL) quark matter with Maxwell construction. The hybrid equation of state (EoS), obtained for different values of bag pressure $B$ and gap parameter $\Delta$, have been used to compute the speed of sound in hybrid star (HS) matter. The structural properties of the HSs in both static and rotating conditions have been calculated in the light of various constraints from different astrophysical and empirical perspectives. The effects of $B$ and $\Delta$ on the EoS and structural properties have been investigated. At a certain density, shortly after phase transition, the HSs become unstable. In static conditions, the mass-radius solutions satisfy the constraints from GW190425, NICER experiment for PSR J0030+0451 and PSR J0740+6620 and from massive pulsars like PSR J0348+0432 and PSR J0740+6620. In rapidly rotating conditions at Kepler frequency, the constraints on maximum mass from the secondary component of GW190814 and that on rotational frequency from fast pulsars like PSR B1937+21 and PSR J1748-2446ad are all satisfied. In slowly rotating conditions, the universality relations in terms of normalized moment of inertia also hold quite well for most of our HS configurations.