Compact stars, such as neutron stars - and their possible transition to black holes - are unique laboratories that allow us to probe the building blocks of matter and their interactions at regimes that terrestrial laboratories cannot explore. These exceptional objects have already led to breakthrough discoveries in nuclear and particle physics, general relativity and high-energy astrophysics. The upcoming generation of observatories and gravitational-wave detectors will continue to nurture innovative and fundamental discoveries. The European COST Action MP1304 Exploring fundamental physics with compact stars (NewCompStar) brings together leading experts in astrophysics, nuclear physics and gravitational physics to address this fascinating but challenging research area through an interdisciplinary approach. In addition to an innovative and well-defined research agenda, the network provides a dedicated training program for a new generation of scientists with wide-ranging expertise and multiple skills oriented also towards knowledge transfer and innovation.

The participating group from Basel has special expertise in the so-called equation of state at extreme densities and temperatures, as they occur in such objects (determining properties like the pressure of matter under such conditions); simulations of core-collapse supernova explosions, which lead to neutron stars or black holes; simulations of neutron star mergers in double neutron star systems; as well predictions of the composition of the ejecta (chemical elements and their isotopes) from such explosions, which play a dominant role in understanding the composition we find presently in the solar system.