The Cooling of the Crab Pulsar

Neutron stars are one of the most exotic objects in the universe. They are complex due to their extremely high densities. Trying to find the equation of state (EOS) exceeding nuclear saturation density is a high priority for nuclear astrophysics. One way to constrain the EOS is to learn more about the cooling processes of neutron stars over time. Stars cool from one of two ways: emission of thermal radiation from the surface or through the emission of neutrinos from the interior of the star.

There’s some circumstantial evidence that the Crab pulsar was formed in an electron-capture supernova, which is one way stars about 8-10 solar masses die. In this type of supernova, the star’s core collapses at the ONeMg stage, and produces a relatively low mass neutron star of around 1.25 Msun. It is not certain the Crab formed this way, but in this talk we explore the possibility of ruling out the electron capture supernova scenario, and of placing constraints on the neutron star EOS, by calculating the cooling of low mass neutron stars and comparing with the measured upper limit on the Crab’s temperature. We do this using an ensemble of nuclear EOSs spanning the current uncertainty in the nuclear symmetry energy and the maximum mass and moment of inertia of neutron stars.