Effect of Dark matter and $σ$-cut potential on radial and non-radial oscillation modes in neutron stars

Abstract

We study the mesonic nonlinear (NL) interaction equation of state (EoS) employing the relativistic mean-field model and investigate the effect of $σ$-cut potential (NL-$σ$ cut) and dark matter (NL DM) on the non-radial and radial oscillation modes of neutron stars. For NL-$σ$ cut, we include the $σ$-cut potential $U_{cut} (σ)$ to study its effect. For the dark matter, we use the neutron decay anomaly model. For each model, we investigate two extreme EoSs, stiff and soft, that cover the entire allowed parameter range from the given model, consistent with the current astrophysical constraints. The EoS and the stellar properties, such as mass and radius, are calculated, and the effect of $σ$-cut and DM is discussed. Both non-radial and radial oscillation modes are computed in the general relativistic framework. We study the non-radial $f$ and $p_1$ mode frequency, damping time, and some qusi-universal relations connecting the frequencies of the $f$-mode to the average density and compactness. The analysis showed that the $f$ and $p_1$ mode frequencies at both 1.4~$M_{\odot}$ and the maximum mass configuration are higher in the NL DM model compared to the NL and NL-$σ$ models. The consistent alignment between our prior parameterizations and current calculations strongly supports the existence of quasi-universal relations that hold true irrespective of the particular matter components involved. For the radial oscillations, we compute 10 lowest-order modes ($f$, $p$), study the radial perturbations as well as the large frequency separation with NL-$σ$ cut and NL DM EoS, showing that the microphysics involved in the NS EoS is imprinted on the frequency separation between different nodes.