Physics of gravitational wave emission and detectionCollin Capano
Measuring the equation of state of dense nuclear matter via gravitational waves involves a combination of general relativity, nuclear physics, and statistical analysis. In the first part of my lectures I will review gravitational-wave emission from neutron-star binaries. We will touch on how a binary’s properties — such as the mass, spin, and tidal deformability of its components — affects the emitted gravitational wave. In the second part, I will cover techniques used to analyze a putative gravitational-wave signal when it is buried in detector noise. We will see how Bayesian analysis of gravitational-wave data yields measurements of a binary’s parameters, which in turn provide insights into the equation of state of the dense nuclear matter found in neutron-star cores.
Neutron star observations and NICER resultsCole Miller
Neutron star cores are expected to reach several times nuclear saturation density, and to have neutron to proton ratios greater than ten. This is a state of matter that cannot be explored in laboratories. Thus nuclear physicists have great interest in astronomical measurements (especially radii) of neutron stars as indicators of the properties of high-density matter. However, prior to 2019, neutron star radii inferred from X-ray observations had potentially large systematic errors; thus these inferred radii were not reliable. I will discuss the different nature of the X-ray data collected using NASA's Neutron Star Interior Composition Explorer (NICER) mission, including why it is believed that the radii inferred from these data are reliable as well as precise. I will also discuss the current state and future prospects for combining X-ray observations and gravitational-wave observations to solidify our understanding of very dense matter.
The maths, physics and astrophysics of binary neutron stars mergersLuciano Rezzolla
After introducing the mathematical framework needed to explore the solution for the combined set of Einstein and hydrodynamic equations, I will review the rapid recent progress made in modelling neutron stars in binary systems and show how the inspiral and merger of these systems is more than a strong source of gravitational waves. Indeed, while the gravitational wave signal can provide tight constraints on the equation of state for matter at nuclear densities, the formation of a black-hole–torus system can explain much of the phenomenology of short gamma-ray bursts, while the the ejection of matter during the merger can shed light on the chemical enrichment of the universe. Finally, I will review how our understanding on the maximum mass and radii of neutron stars has improved with the detection of GW170817.
Equation of state for nuclear matter with correlations and clusteringGerd Röpke
Nuclear systems are treated within a quantum statistical approach. Correlations and cluster formation are relevant for the properties of warm and dense nuclear matter. The description is challenging, and different approaches are presented. The equation of state, symmetry energy, the composition, Bose condensation of bound fermions, and the contribution of continuum correlation are discussed. At increasing density, bound states disappear because of Pauli blocking and merge with the continuum of scattering states. These phenomena are of relevance for different applications in astrophysics, heavy ion collisions, and nuclear structure. The investigation of supernova explosions, the structure of the crust of neutron stars, and the evolution of neutron star mergers demands a description of nuclear matter taking correlations and cluster formation into account.
Equation of state for binary neutron star mergers and core-collapse supernovaeArmen Sedrakian
In simulations of compact stars, binary mergers and core-collapse supernovae an equation of state (EoS) is needed to close the system of combined Einstein and hydrodynamics equations. I will discuss requirements for such an equation of state and different existing approaches to construct one.
Introduction to the CompOSE databaseMicaela Oertel
I will present the data base Compose, part of the PHAROS project, which contains EoS data ready for use in simulations. Hands-on sessions showing the different functionalities of Compose will complete my lectures.