SIMBAD references

The effect of the magnetic field on the energy loss rate in the direct Urca reactions is studied. The general expression for the neutrino emissivity at arbitrary magnetic field B is derived. The main emphasis is laid on a case, in which the field is not superstrong, and charged reacting particles (e and p) populate many Landau levels. The magnetic field keeps the process operative if Δk/k_Fn≲N_Fp^–2/3 (N_Fp is the number of the Landau levels populated by protons and Δk =k_Fn-k_Fp-k_Fe), that is beyond the well-known switch-on limit in the absence of the field, Δk<0. Cooling of magnetized neutron stars with strong neutron superfluid in the outer cores and nonsuperfluid inner cores is simulated. The magnetic field near the stellar center speeds up the cooling if the stellar mass M is slightly less than the minimum mass M_c, at which the direct Urca reaction becomes allowed for B=0. If B=3x10¹⁶G, the affected mass range is M_c-M≲0.1M_c, while for B=3x10¹⁵G the range is M_c-M≲0.015M_c. This may influence a theoretical interpretation of the observed thermal radiation as illustrated for the Geminga pulsar. The case of superstrong magnetic fields (B>10¹⁸G), such that e and p populate only the lowest Landau levels is briefly outlined.