Multi-Physics Constraints at Different Densities to Probe Nuclear Symmetry Energy in Hyperonic Neutron Stars

Abstract

The appearance of strangeness in the form of hyperons within the inner core of neutron stars is expected to affect its detectable properties, such as its global structure or gravitational wave emission. This work explores the parameter space of hyperonic stars within the framework of the Relativistic Mean Field model allowed by the present uncertainties in the state-of-the-art nuclear and hypernuclear experimental data. We impose multi-physics constraints at different density regimes to restrict the parameter space: Chiral effective field theory, heavy-ion collision data, and multi-messenger astrophysical observations of neutron stars. We investigate possible correlations between empirical nuclear and hypernuclear parameters, particularly the symmetry energy and its slope, with observable properties of neutron stars. We do not find a correlation for the hyperon parameters and the astrophysical data. However, the inclusion of hyperons generates a tension between the astrophysical and heavy-ion data constraining considerably the available parameter space.

Role of vector self-interaction in Neutron Star properties

“…However, the parameter is fixed such that the EoS should able to reproduce the maximum observed neutron star mass. In many works the vector self interaction is either ignored [16,18,19,31] or they are fixed to constant value [15,32] by choosing a particular EoS model. In this work we will consider the variation of all nuclear saturation parameters along with and the ranges for each of the variables are provided in Table 1.…”

“…By applying the maximum mass constraint resulting from the observed massive pulsar, one can limit the allowed range for . Other physical constraints considered in different works include the constraints following chiral effective field theory ( EFT), which describes the behaviour of low-density nuclear matter (0.5-1.4 0 ) [44,45,46,18,19,47,48]. At such low densities, nuclear matter is insensitive to [35].…”

“…Previous studies in the literature have shown that there may exist correlations among certain nuclear saturation parameters and neutron star observables, such as the slope of the symmetry energy and the radius of a 1.4 ⊙ neutron star [20,21,22,23,24,25,26,27]. However as such correlations are not observed for some other EoS models [16,18,19,28,29,30,31], it is not clear whether these are physical or spurious. In this work, we probe in particular…”

“…There are two main approaches of describing the nuclear EoS [6], the first is microscopic or ab-initio while the other is phenomenological (effective theories with parameters fitted to reproduce saturation nuclear properties) [7,8,9,10,11,12]. In this work, we employ the Relativistic Mean Field (RMF) model, which is a relativistic effective field theoretical model successfully applied to a wide range of nuclei and nuclear matter [13,14,15,16,17,18,19].…”

Constraining the equation of state of hybrid stars using recent information from multidisciplinary physics

“…In our previous work (Ghosh et al 2022a), it was explicitly demonstrated that including the statistical re-weighting using χ-squared statistics might change the posterior probability distribution slightly, but it does not significantly alter the physical correlation between nuclear empirical parameters and astrophysical observables. Many other works have followed the same scheme (Kurkela et al 2014;Most et al 2018;Annala et al 2018;Annala et al 2020;Ghosh et al 2022b). A similar scheme was employed to study the correlations between nuclear parameters in various works (Chatterjee et al 2017;Margueron et al 2018;Ghosh et al 2022a,b).…”