Features

The library contains functions for precomputing properties for sequences of neutron stars and interpolating those to any parameter. Further, the sequences can be written and loaded from files in a hdf5 based format. Sequences can be computed using the TOV solver provided by the library, but also created using sampled data from other sources (note this would also allow for NS solutions from modified GR theories, provided that the same properties are still meaningful). The stored NS properties are: gravitational mass, baryonic mass, central matter state, moment of inertia, circumferential radius, and tidal deformability.

The framework provides a representation of generic sequences and a specialization representing stable branches. Sequences are spanning a range of central densities, and present NS properties as functions of central pseudo-enthalpy. Branches are sequences that restrict the range to a segment where the gravitational mass is strictly increasing with pseudo-enthalpy, and which extends up to the maximum mass.

Branches also offer all properties as function of the gravitational mass, and they provide the maximum mass as wel as the properties of the corresponding NS model.

We note that the EOS framework insists on causality, and therefore the same guarantee extends to the star sequences. By design, the library actively prevents the computation of TOV solutions with causality-violating regions. Even though the equations for the static TOV solution do not break down for such EOS, this does not hold for dynamic evolution equations that govern, e.g., oscillations. Such models are considered physically meaningless.

It may happen that the central density exceeds the EOS validity range before the maximum NS mass is reached. The library distinguishes this case, and allows to query whether a branch extends to the physical maximum or the one given by the EOS range.