Neutron stars are some of the most extraordinary objects in Nature. Their cores contain strongly interacting matter at densities substantially higher than what can be created in modern collider experiments, and thereby function as stellar laboratories for nuclear and quark matter. At the same time, the strong gravitational fields of neutron stars provide a unique testing ground for modified theories of gravity, and may offer contraints for various Beyond the Standard Model theories.  

The physics of neutron stars can be studied from various perspectives. On one hand, their macroscopic properties are being measured at a rapidly increasing precision with a broad set of tools. In particular, the anticipated observation of gravitational waves from neutron star mergers is expected to open a fundamentally new observational window into the bulk properties of the stars and the matter they contain. 

At the same time, one may approach the problem from the microscopic perspective, and understanding the physics of dense QCD matter is indeed a prominent problem at the intersection of theoretical particle and nuclear physics. First principles approaches, such as Chiral Effective Theory, perturbative QCD and lattice field theory, all have their severe limitations, and it is widely accepted by now that progress towards understanding the properties of the matter found in neutron star cores requires a strong interdiciplinary effort. 

The aim of our TH Institute is to bring together researchers from particle and nuclear theory as well as from observational astrophysics, who study the physics of dense strongly interacting matter and neutron stars from maximally different but complementary viewpoints. The key topics addressed by the Institute include:

- Extending the theoretical description of nuclear matter beyond saturation density

- The Equation of State of quark matter and its use in constraining neutron star matter

- Recent advances in neutron star observations; in particular the prospects of using gravitational wave detection to learn about neutron star matter

- Complementary approaches: phenomenological models, holography, etc.

- Neutron stars as laboratories for modified gravity theories and Beyond the Standard Model physics

Organisers : Aleksi Kurkela, Mark Alford, Diego Blas, Luciano Rezzolla, Achim Schwenk, Aleksi Vuorinen