Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter

Understand

We propose that the observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the recent onset of the breaking and formation of neutron Cooper pairs in the 3P2 channel.

• We find that the critical temperature for this superfluid transition is ~0.5x10^9 K.
• The observed rapidity of the cooling implies that protons were already in a superconducting state with a larger critical temperature.
• Our prediction that this cooling will continue for several decades at the present rate can be tested by continuous monitoring of this neutron star.