Abstract
A Bayesian analysis of the possible behaviors of the dense matter equation of state informed by recent LIGO-Virgo as well as NICER measurements reveals that all the present observations are compatible with a fully nucleonic hypothesis for the composition of dense matter, even in the core of the most massive pulsar PSR J0740+6620. Under the hypothesis of a nucleonic composition, we extract the most general behavior of the energy per particle of symmetric matter and density dependence of the symmetry energy, compatible with the astrophysical observations as well as our present knowledge of low-energy nuclear physics from effective field theory predictions and experimental nuclear mass data. These results can be used as a null hypothesis to be confronted with future constraints on dense matter to search for possible exotic degrees of freedom.
Highlights
The exceptional progress of multi-messenger astronomy on different astrophysical sources of dense matter has very recently led to quantitative measurements of various properties of neutron stars (NS), such as the correlation between mass and radius (M-R) from X-ray timing with NICER [1,2,3,4] and the tidal polarizability from gravitational wave (GW) LIGO/Virgo data [5,6,7,8,9]
LD: in this sample, the models are selected by the strict filter from the chiral effective field-theory (EFT) calculation, where the energy per nucleon of symmetric nuclear matter (SNM) and pure neutron matter (PNM) of the model are compared with the corresponding energy bands of Reference [35], enlarged by 5%
This can be explained by the fact that the prior intervals of the empirical parameters are chosen based on the current knowledge provided by nuclear physics, in which the deviations of Esat, nsat, and Ksat are already relatively small
Summary
The exceptional progress of multi-messenger astronomy on different astrophysical sources of dense matter has very recently led to quantitative measurements of various properties of neutron stars (NS), such as the correlation between mass and radius (M-R) from X-ray timing with NICER [1,2,3,4] and the tidal polarizability from gravitational wave (GW) LIGO/Virgo data [5,6,7,8,9]. To identify the observables pointing towards more exotic constituents, it is important to quantitatively evaluate the space of parameters and observables that are compatible with the nucleonic hypothesis To this end, meta-modelling techniques were proposed [19,20,21,22,23,24,25], which allow for exploring the complete parameter space of hadronic equations of state, and predicting the astrophysical observables with uncertainties controlled by our present theoretical and experimental knowledge of nuclear physics.
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