Magnetic field determines observational properties of neutron stars

Neutron stars (NSs) are seen as radio pulsars, magnetars and central compact objects. Magnetars and central compact objects are bright, young NSs seen close to the centra of supernova remnants. Magnetars are extremely magnetised neutron stars which shows a variety of observational phenomena associated to their magnetic fields, such as burst and giant flashes. Both magnetars and central compact objects are much hotter than it is excepted even for very young neutron stars. We perform first three-dimensional simulations of the magneto-thermal evolution using a spectral MHD code. Our results show that presence of strong toroidal magnetic field in magnetars is necessary to explain their quiescent thermal emission, in particular a formation of a single hot spot. Using our thermal maps we are able to explain light curves of 10 out of 19 magnetars in quiescence. In the case of the central compact objects, we test the configuration of magnetic field formed as a result of stochastic dynamo. Such a magnetic field consists of multiple randomly orientated loops of magnetic field. The global dipolar field slowly formed as a result of the Hall and Ohmic evolution. In our simulations we see 5-7% pulsed fraction, formation of a few compact hot regions and difference of two times in temperature between hot and cold regions typical for observations of the central compact objects.