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Rajesh Maiti

Publications and source records attributed to Rajesh Maiti.

3 recordsLinked to original sources

$f$-mode Oscillations for Hyperons and H-dibaryons in Neutron Stars

The fundamental ($f$-mode) oscillations of neutron stars are studied within the quark meson coupling model, a relativistic Hartree-Fock theory of dense nuclear matter, which takes into account the self-consistent modification of the valence quark structure of the bound baryons in the associated strong Lorentz scalar mean fields. For the first time, hyperons and H-dibaryons are included, along with the effects of potential additional short-range repulsion within this scheme, and their influence on $f$-modes is investigated. Universal relations are studied within the relativistic Cowling approximation and compared against those in the existing literature for potential applications in gravitational wave asteroseismology.

astro-ph.HE

PSR J0614-3329: A NICER case for Strange Quark Stars

Precise measurements of neutron star masses and radii by the NICER mission impose important constraints on the nuclear equation of state. The most recent NICER measurement of PSR J0614-3329 reported an equatorial radius of $R_{eq} = 10.29^{+1.01}_{-0.86}$ km for a mass of $M = 1.44^{+0.06}_{-0.07} M_{\odot}$. Considering all the NICER measurements to date, we find substantial evidence using Bayesian hypothesis ranking for strange quark stars over physically motivated models of neutron stars compatible with this low radius. This provides a strong case for quark matter in neutron stars and also for the possible existence of strange quark stars, a consequence of the Bodmer-Witten hypothesis, suggesting that they could be considered among the population of compact stars during analyses of astrophysical data. Using a wide sample of equations of state, we report the nucleonic equations of state that best fit current observations and rule out one model of strange quark matter.

astro-ph.HE

Investigating the role of nuclear parameters in Neutron Star oscillations: a model comparison

Recent studies based on the relativistic mean field (RMF) model found certain nuclear empirical parameters, in particular the nucleon effective mass, to be strongly correlated with observable properties of Neutron Stars (NSs), such as the frequencies of $f-$mode oscillations. This shows the potential to constrain the values of effective mass from future observations of $f-$modes. One of our primary goals of this work is to investigate whether such correlations are physical or an artifact of the underlying nuclear model. To test this, we perform a comparative study of the correlations between NS astrophysical observables and nuclear physics parameters using two different equation of state models based on RMF theory and non-relativistic Meta-Modelling (MM) scheme. The nuclear meta-model does not assume any underlying nuclear model and therefore allows us to test the model dependence of the results. The calculations of the $f-$mode characteristics are performed within the relativistic Cowling approximation. We use state-of-the-art nuclear microscopic calculations at low density and multi-messenger astrophysical data at high-density within a Bayesian-inspired scheme to constrain the parameter space of the nuclear models. From the posterior distribution, we probe the underlying correlations among nuclear parameters and with NS observables. We find that the correlation between the symmetry energy and its slope is physical, while that of the nucleon effective mass with NS observables is model-dependent. The study shows that the effective mass governs the high density behaviour in RMF models, while in the MM it is controlled by the higher order saturation parameters, and hence probes the possibility of constraining them from future $f$-mode observations. The findings of this investigation are interesting both for astrophysics as well as nuclear physics communities.

astro-ph.HE