The Impact of Magnetic Field on the Thermal Evolution of Neutron Stars

Abstract

The impact of strong magnetic fields G on the thermal evolution of neutron stars is investigated, 13B 1 10 including crustal heating by magnetic field decay. For this purpose, we perform 2D cooling simulations with anisotropic thermal conductivity considering all relevant neutrino emission processes for realistic neutron stars. The standard cooling models of neutron stars are called into question by showing that the magnetic field has relevant (and in many cases dominant) effects on the thermal evolution. The presence of the magnetic field significantly affects the thermal surface distribution and the cooling history of these objects during both the early neutrino cooling era and the late photon cooling era. The minimal cooling scenario is thus more complex than generally assumed. A consistent magnetothermal evolution of magnetized neutron stars is needed to explain the observations.

X-ray emission from isolated neutron stars

“…They have been interpreted as proton cyclotron lines or as H and/or He atomic transitions, falling in the soft X-ray range due to the effect of a high magnetic field on the binding energies. Both interpretations require B∼ 10 13 − 10 14 G, broadly consistent with the values of 2.5 and 3.4 10 13 G derived from the timing parameters of RX J0720.4−3125 and RX J1308.6+2127 assuming dipole braking 2 .…”

Grand unification of neutron stars

“…A theory of magnetothermal evolution in neutron stars has recently been developed in a series of papers (91)(92)(93)(94). Motivated largely by an apparent correlation between inferred B field and surface temperature in a wide range of neutron stars, including RPPs, INSs, and magnetars (91) (but see ref.…”

Joule heating governing the cooling of magnetized neutron stars

“…Therefore, the cooling evolution time should be corrected according to the prescription for the magnetic field decay in order to compare with the observations properly. A detailed comparison with observational sources is presented in [10] and is summarized in the next section. …”

“…3 our simulations with observational data of NSs covering about three orders of magnitude in magnetic field strength: from radio-pulsars (B ≃ 10 12 G) and isolated radioquiet NSs (B ≃ 10 13 G) to recent magnetar candidates (B ≃ 10 14−15 G). The sources considered here are listed in Table 1 of [10], with the corresponding references.…”