Speaker
Description
We study the possibility of existence of deconfined quark matter in the core of neutron stars and non-radial oscillation modes in neutron and hybrid stars. A relativistic mean field model is used to describe the nuclear matter at low densities and zero temperature while Nambu--Jona-Lasinio model is used to describe the quark matter at high densities and zero temperature. A Gibbs construct is used to describe the quark-hadron phase transition at large densities. Within the model, as the density increases, a mixed phase appears at density about $2.5$ times the nuclear matter saturation density $(\rho_0)$ and ends at density about $5~\rho_0$ beyond which the pure quark matter phase appears. It turns out that a stable hybrid star of maximum mass, $M=2.27~M_{\odot}$ with radius $R=14$ km, can exist with the quark matter in the core in a mixed phase only. The quark-hadron phase transition in the core of maximum mass hybrid star occurs at radial distance, $r_c=0.27R$ where the equilibrium speed of sound shows a discontinuity. Existence of quark matter in the core enhances the non-radial oscillation frequencies in hybrid stars compared to neutron stars of the same mass. This enhancement is more for the $g$ modes. The non-radial oscillation frequencies depend on the vector coupling in NJL model. The values of $g$ and $f$ mode frequencies decrease with increase the vector coupling in quark matter.
| Session | Heavy Ions and QCD |
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