The Magnetic Field Dynamics in Neutron Stars

Neutron stars host some of the strongest magnetic fields in the Universe. We observe neutron stars because of these magnetic fields. And yet, despite 50 years of theoretical studies and observations, the magnetic field configuration inside neutron stars is not fully understood.

Does an equilibrium configuration for the magnetic field inside a neutron exist? How is such an equilibrium reached? What is the role of turbulence in the evolution? And how does it affect astrophysical observables?

In the next years, our collaborative research project "MERLIN" will try to answer these fundamental questions.

Neutron stars are born after the collapse of massive stellar cores and associated to powerful explosions called supernovae. During the collapse, about a Solar mass of material is squeezed into a radius of about ten kilometers. This results in averaged densities above those of the atomic nucleus and in a gravitational field at the neutron star's surface of hundreds billion times that of Earth's gravitational field. In such extreme objects the magnetic field generated during the collapse reaches intensities of more than hundreds of million times stronger than Earth's magnetic field and a billion (one thousand million) times stronger than medical magnetic resonance imaging machines. These magnetic fields are the reason why astronomers observe neutron stars as pulsars. Electromagnetic waves emitted by neutron stars are routinely captured by telescopes at radio and X-ray frequencies and allow the measurement of the the mass and radius of neutron stars. In turn, thus informs on the dense and unknown star matter. In the near future, isolated neutron stars might also be observed via gravitational waves. These "gravitational wave pulsars" will convey information that is complementary to electromagnetic waves.

The MERLIN project will provide the theoretical foundations for future observations by investigating the magnetic field dynamics in neutron star interiors and the role of turbulence in its evolution. We will employ Einstein's general relativity to model the development of the super strong magnetic fields and create accurate astrophysical models. The project will develop at Warsaw (Poland) and Jena (Germany) in the groups of Prof.dr.Haskell and Prof.dr.Bernuzzi. The two teams will combine their expertise in pulsar astrophysics and in numerical simulations of neutron stars.

The MERLIN project is funded by the Deutsche Forschungsgemeinschaft (DFG) and the Narodowe Centrum Nauki (NCN) under the EU weave initiative.