QM 2022

Non-radial oscillation modes in hybrid stars: consequences of a mixed phase

8 Apr 2022, 14:40

4m

Poster Baryon rich matter, neutron stars, and gravitational waves Poster Session 3 T10

Speaker

Mr Deepak Kumar (Physical Research Laboratory)

Description

We study the possible existence of deconfine quark matter in the core of neutron stars. A relativistic mean field model is used to describe the nuclear matter at low densities while Nambu--Jona-Lasinio model is used to describe the quark matter at high densities. A Gibbs construct is used to describe the quark-hadron phase transition at large densities and at zero temperature. Within the model, as the density is increased, a mixed phase appears at about $2.5$ times the nuclear matter saturation density $({\rho }_0)$ and ends at about $5{\rho }_0$ beyond which pure quark matter phase appear. It turns out that a stable hybrid star of maximum mass, $M=2.27M_{\odot }$ with radius $R=14$ km, can exist with a quark matter core in a mixed phase only. As the density decreases from the center to the surface, there is a sharp increase of the velocity of sound at the point where the quark-hadron phase transition occurs. This leads to the possibility of low frequency non-radial oscillations, the $g$ modes, in hybrid stars in contrast to canonical neutron stars which do not have such quark matter core. The higher $f$ modes frequencies of neutron stars get enhanced in the presence of quark matter core in hybrid stars. The magnitude of $g$ mode frequencies decrease with increase the repulsive interaction in quark matter.