Magneto-thermal evolution of neutron stars

By José A. Pons, J. Miralles, U. Geppert. 2008

232 citations recorded by the source corpus.

Context. The presence of magnetic fields in the crust of neutron stars c auses a non-spherically symmetric temperature distribution. The strong temperature dependence of the magnetic diffusivity and thermal conductivity, together with the heat generated by magnetic dissipation, couple the magnetic and thermal evolution of NSs, that cannot be formulated as separated one‐dimensional problems. Aims. We study the mutual influence of thermal and magnetic evoluti on in a neutron star’s crust in axial symmetry. Taking into account realistic microphysical inputs, we find the heat rel eased by Joule effect consistent with the circulation of currents in the crust , and we incorporate its effects in 2‐dimensional cooling calculations. Methods. We solve the induction equation numerically using a hybrid method (spectral in angles, but a finite‐di fferences scheme in the radial direction), coupled to the thermal diffusion equation. To improve the boundary conditions, we also revisit the envelope stationary solutions updating the well known Tb− Ts‐relations to include the effect of 2‐D heat transfer calculations and new microphysical inputs. Results. We present the first long term 2‐dimensional simulations of t he coupled magneto-thermal evolution of neutron stars. This substantially improves previous works in which a very crude approximation in at least one of the parts (thermal or magnetic diffusion) has been adopted. Our results show that the feedback between Joule heating and magnetic diffusion is strong, resulting in a faster dissipation of the stronger fields during the first 10 5 − 10 6 years of a NS’s life. As a consequence, all neutron stars born with fields larger than a critical value (> 5×10 13 G) reach similar field strengths (≈ 2−3×10 13 G) at late times. Irrespectively of the initial magnetic field strength, after 10 6 years the temperature becomes so low that the magnetic diffusion timescale becomes longer than the typical ages of radio‐pulsars, thus resulting in apparently no diss ipation of the field in old NS. We also confirm the strong correl ation between the magnetic field and the surface temperature of relatively young NSs discussed in preliminary works. The effective temperature of models with strong internal toroidal components are systematically higher than those of models with purely poloidal fie lds, due to the additional energy reservoir stored in the toroidal field tha t is gradually released as the field dissipates.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/2ccb91afb906ad1b2a228f639e7256a6a20bbe1f

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Citations in the corpus

THE McGILL MAGNETAR CATALOG (2013, background): “…support the idea that there is a continuum in the X-ray luminosities of high-B radio pulsars and magnetars (see An et al. 2012 for further discussion) as expected on physical grounds based on magnetic dissipation and expected magnetothermal evolution (Thompson & Duncan 1996; Pons et al. 2009).”
Unifying the observational diversity of isolated neutron stars via magneto-thermal evolution models. (2013, methodology): “Perna & Pons (2011) combined results from the magnetothermal evolution of NSs (Pons et al. 2009), with a computation of the magnetic stresses exerted on the NS crust.”
A UNIFIED MODEL OF THE MAGNETAR AND RADIO PULSAR BURSTING PHENOMENOLOGY (2011, background): “The temperature of the crust at different ages is given by the results of Pons et al. (2009), where the interplay between the thermal and magnetic field evolution of magnetars was studied.”