Supernova explosions of massive supergiant stars leave behind neutron stars that are stars containing matter at the highest densities in the universe. Understanding the nature and properties of this matter is a major unsolved problem in fundamental physics.
Research led by Dr Andreas Schmitt, from Mathematical Sciences and the Southampton Theory Astrophysics and Gravity (STAG) Research Centre, used methods from string theory to shed new light on our understanding of this dense nuclear and quark matter that is governed by one of the four fundamental forces of nature, the strong nuclear force.
Solving a mystery of fundamental physics
The first neutron star was discovered almost 60 years ago and there are estimated to be around one billion neutron stars in the Milky Way. Since that first discovery, researchers have been striving to ‘look inside’ the stars and solve the mystery of their interiors. The underlying theory of the strong nuclear force Quantum Chromodynamics (QCD) is notoriously difficult to solve for matter at these extreme densities.
Andreas, working with former Southampton colleagues Nicolas Kovensky and Aaron Poole, applied a mathematical correspondence between string theory and the more traditional theories such as QCD - the gauge-string correspondence, also known as holography.
He has constructed the first entirely ‘holographic’ neutron star, including all layers of the star, that meets known astrophysical constraints.
The research is a breakthrough in the understanding of neutron stars and the role of the holographic principle. Previous studies have usually relied on a patchwork of different models and theories. The research is having an impact on several fields of fundamental physics and astronomy and is opening doors to future research at the interface of string theory, particle physics and astrophysics.
Research on neutron stars is going through fascinating times and I am excited to contribute to our theoretical understanding of ultra-dense matter on a fundamental level – employing cutting-edge methods from quantum field theory and string theory.
In a series of works, presented at several international conferences, Andreas and his collaborators have further tested the holographic predictions against known results from QCD and were able to develop novel string-theoretic descriptions of dense matter, such as ‘quarkyonic’ matter, that otherwise require over-simplified models.
Understanding the physics of neutron stars requires the use of a plethora of mathematical tools from quantum field theory to fluid dynamics and artificial intelligence (AI). Theoretical progress, such as Andreas’ research, is used in close connection with new astrophysical data such as X-ray spectra from the Neutron Star Interior Composition Explorer on the International Space Station and gravitational wave data from the Laser Interferometer Gravitational-Wave Observatory in the USA.
Related publications
Thermal pion condensation: holography meets lattice QCD, Nicolas Kovensky, Andreas Schmitt, 2024, Springer Nature Link
Building a realistic neutron star from holography, Nicolas Kovensky, Aaron Poole and Andreas Schmitt, 2022, APS Physical Review Journals
Predictions for neutron stars from holographic nuclear matter, Nicolas Kovensky, Aaron Poole and Andreas Schmitt, 2022, SciPost
Holographic quarkyonic matter, Nicolas Kovensky, Andreas Schmitt, 2020, Springer Nature Link
