Recent development in multi-messenger astronomy leading to a wealth of new observational results through gravitational waves (LIGO/VIRGO) and X-ray spectra (NICER) have opened new possibilities to understand hadronic matter at densities at and beyond our terrestrial reach. They provide new constraints to the theories of nuclear physics, where an absolute energy density functional from ab-initio modelling is still not available.

General relativity guarantees that there is a unique one-to-one correspondence between static observables of neutron stars such as mass-radius relation or tidal deformability and equation of state (EoS) of beta equilibrated matter. However, these static properties are not enough to predict the composition of the interiors of neutron stars. In this talk, I will present EoS meta-modelling technique which was developed in our group, particularly to emphasize that even within pure nucleonic assumption, there is a big room for ambiguity in the composition. I will also demonstrate how recent observational data put bounds on the high density nucleonic matter using this (nucleonic) meta-modelling approach.