The magnetic and thermal evolution of neutron stars is a very complex process with many, also non-linear, interactions. For a decent understanding of neutron star physics, these evolutions cannot be considered isolated. A brief overview is presented, which describes the main magneto -thermal interactions that determine the fate both of isolated neutron stars and accreting ones. Special attention is devoted to the interplay of thermal and magnetic evolution at the polar cap of radio pulsars. There, a strong meridional temperature gradient is maintained over the lifetime of radio pulsars. It may be strong enough to drive thermoelectric magnetic field creation which perpetuate a toroidal magnetic field around the polar cap rim. Such a local field component may amplify and curve the poloidal surface field at the cap, forming a strong and small scale magnetic field there as required for the radio emission of pulsars.Key words: stars: neutron -stars: magnetic fields -pulsars: general -stars: interiors
PREFACEWhen I started to try to understand some aspects of neutron star physics, one of the first papers I read was Srinivasan & van den Heuvel (1982) about the evolution of millisecond pulsars. Then the connection between the (at that time in optical light) invisible pulsars and the fascinating manifestations of supernova remnants (Srinivasan et al. 1984) increased my interest in this branch of astrophysics. The observation of millisecond pulsars in the early eighties was a challenge, which was met by Prof. Srinivasan and his colleagues (see e.g. Bhattacharya & Srinivasan (1986);Srinivasan (1989)). Later the pioneering work of Srinivasan et al. (1990) triggered my interest to understand how the very long-lived core magnetic field is affected by the rotational history of neutron stars and how the evolutions of core and crustal field are coupled to each other. Meanwhile Prof. Srinivasan enriched our knowledge about neutron stars by many contributions, among others about their evolution in accreting binary systems, about the recycling of old pulsars to millisecond pulsars, about the supernova remnants and pulsar wind nebulae which are results of neutron star births, about the use of radiotelescope for pulsar observations and about many other topics. As far as I can see being a far distant observer, Prof. Srinivasan succeeded also in the formation of a group of excellent and worldwide renown Indian scientists working in the field of neutron star physics.⋆ E-mail:ulrich.geppert@dlr.deMay be there exists a not yet discovered age-relativistic effect that makes the time running faster when seen by an aging person. It seems to be this effect that made me surprised to recognize that Prof. Srinivasan celebrates already his 75th birthday. This special issue is a good opportunity to esteem his life-work and I am happy that I can contribute to it.
THE MANY FACETS OF MAGNETO -THERMAL INTERACTIONS