Dmitry Ofengeim, Racah Institute of Physics, Hebrew University of Jerusalem, Israel — May 27, 2024

Determining the equation of state (EoS) of superdense matter in neutron star (NS) interiors is an intriguing problem of modern physics. In the literature one can find several hundreds of EoS models —nucleonic, hyperonic, hybrid (i.e. with deconfined quarks)—based on different approaches to the superdense matter microphysics. In spite of the differences of various EoSs, it is widely known that some macroscopic NS properties show universal correlations which are largely independent of a specific EoS model. Such relations help to interpret NS observations and, ultimately, to constrain the EoS. In this talk, I present a novel class of universal phenomenological relations for very basic properties of NS, their mass-radius curve and pressure-density dependence (i.e the EoS itself). They explore the idea that for a given EoS the maximum-mass NS (Oppenheimer-Volkoff limit) provides a key scale for all NSs. With the relations developed, I build an explicit analytic mapping from mass-radius curves to EoSs (the inverse Oppenheimer-Volkoff mapping), which I use to construct a method for inferring the EoS from observed NS masses and radii. Application of it to existing observations yields the strict constraints the properties of superdense matter.