Talk detail

Participant	Rezzolla, Luciano
Institution	Albert Einstein Institute, Max-Planck Institute for Gravitational Physics - Am Muehlenberg,1 - Potsdam - - Germany

Session	TC2	Accepted		Order	Time
Talk	Oral abstract	Title	Electromagnetic counterparts from the merger of binary black holes
Co-authors
Abstract	Recent years have seen a major progress in numerical relativity and the solution of the simplest and yet among the most challenging problems in classical general relativity: that of the evolution of two objects interacting only gravitationally. I will review the results obtained so far when modelling binaries of black holes and discuss how the combined observation of electromagnetic and gravitational signals can increase their detection and provide a wealth of astrophysical and cosmological information.

Session	SN3	Accepted		Order	Time
Talk	Oral abstract	Title	Instability-driven evolution of poloidal magnetic fields in relativistic stars
Co-authors
Abstract	The problem of the stability of magnetic fields in stars has a long history and has been investigated in detail in perturbation theory. Here we consider the nonlinear evolution of a nonrotating neutron star with a purely poloidal magnetic field, in general relativity. We find that an instability develops in the region of the closed magnetic field lines and over an Alfven timescale, as predicted by perturbation theory. After the initial unstable growth, our evolutions show that a toroidal magnetic field component is generated, which increases until it is locally comparable in strength with the poloidal one. On longer timescales the system relaxes to a new non-axisymmetric configuration with a reorganization of the stellar structure and large-amplitude oscillations, mostly in the fundamental mode. We discuss the energies involved in the instability and the impact they may have on the phenomenology of magnetar flares and on their detectability through gravitational-wave emission.