Magnetic Field Effects upon Neutron Star Cooling

The principal mechanism for neutron-star cooling during the early period of its thermal evolution is the emission of neutrinos. Because the neutrino luminosity is very large compared to the photon luminosity, most approximations leave any small effects upon the photon luminosity during the early part of the evolution as ignorable. However, for a field strength of H similar to 10(12) gauss, taking those effects into consideration in terms of a decreased photon flux from the surface means that the energy not released from the surface as photons is still trapped within the star. Energy conservation requires that neutrino emission must make up for the difference, thereby modifying the onset of the photon era of cooling. A magnetic field of large magnitude will change the surface temperature. A proper treatment of the neutron-star cooling problem in a large magnetic field requires that tangential heat flow be taken into account. This presentation shows the preliminary results of a study that is leading toward a full two-dimensional calculation of the thermal evolution.