The Physics of Neutron Stars

TLDR

Neutron stars are among the densest objects in the universe, serving as astrophysical laboratories that probe dense matter physics and link nuclear, particle, and astrophysics through extreme conditions such as hyperon‑rich matter, deconfined quarks, superfluidity, superconductivity, neutrino opacity, and magnetic fields exceeding 10^13 G. This work aims to describe the formation, structure, internal composition, and evolutionary pathways of neutron stars. We use observations of binary pulsars, isolated neutron star thermal emission, pulsar glitches, and accreting neutron star quasi‑periodic oscillations to infer masses, radii, temperatures, ages, and internal compositions.

Abstract

Neutron stars are some of the densest manifestations of massive objects in the universe. They are ideal astrophysical laboratories for testing theories of dense matter physics and provide connections among nuclear physics, particle physics and astrophysics. Neutron stars may exhibit conditions and phenomena not observed elsewhere, such as hyperon-dominated matter, deconfined quark matter, superfluidity and superconductivity with critical temperatures near ${10^{10}}$ kelvin, opaqueness to neutrinos, and magnetic fields in excess of $10^{13}$ Gauss. Here, we describe the formation, structure, internal composition and evolution of neutron stars. Observations that include studies of binary pulsars, thermal emission from isolated neutron stars, glitches from pulsars and quasi-periodic oscillations from accreting neutron stars provide information about neutron star masses, radii, temperatures, ages and internal compositions.