QCD Equation of State of Dense Nuclear Matter from a Bayesian Analysis of Heavy-Ion Collision Data.

Bayesian methods are used to constrain the density dependence of the QCD equation of state (EOS) for dense nuclear matter using the data of mean transverse kinetic energy and elliptic flow of protons from heavy ion collisions (HICs), in the beam energy range sqrt[s_{NN}]=2-10  GeV. The analysis yields tight constraints on the density dependent EOS up to 4 times the nuclear saturation density. The extracted EOS yields good agreement with other observables measured in HIC experiments and constraints from astrophysical observations both of which were not used in the inference.

Gravitational Waves from a Core g Mode in Supernovae as Probes of the High-Density Equation of State.

Using relativistic supernova simulations of massive progenitor stars with a quark-hadron equation of state (EOS) and a purely hadronic EOS, we identify a distinctive feature in the gravitational-wave signal that originates from a buoyancy-driven mode (g mode) below the proto-neutron star convection zone. The mode frequency lies in the range 200≲f≲800  Hz and decreases with time. As the mode lives in the core of the proto-neutron star, its frequency and power are highly sensitive to the EOS, in particular the sound speed around twice saturation density.

Heavy-element production in a compact object merger observed by JWST.

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs), sources of high-frequency gravitational waves (GWs) and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process). Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs.

Probing the core of the strong nuclear interaction.

The strong nuclear interaction between nucleons (protons and neutrons) is the effective force that holds the atomic nucleus together. This force stems from fundamental interactions between quarks and gluons (the constituents of nucleons) that are described by the equations of quantum chromodynamics. However, as these equations cannot be solved directly, nuclear interactions are described using simplified models, which are well constrained at typical inter-nucleon distances but not at shorter distances.