High Density with Elliptic Flows

Abstract

The elliptic flow of emitted particles and fragments observed in heavy-ion reactions at high energy has become an important observable reflecting the pressure generated in the dense collision zone. More recently, the strength of the nuclear symmetry energy has been investigated by measuring the ratios or differences of the elliptic flows exhibited by neutrons and charged particles in 197Au+197Au collisions at 400 MeV/nucleon incident energy at the GSI laboratory. A moderately soft to linear dependence on density was deduced for a range of densities shown to reach beyond twice the saturation value in these experiments. The known sources of uncertainties and possible model dependencies were thoroughly studied with transport models of the UrQMD and Tuebingen QMD type. A new source of information on the nuclear equation of state at high density has opened up with the observation of the first LIGO and Virgo GW170817 gravitational wave signal from a neutron star merger. The quantitative comparison of terrestrial and celestial results on the basis of measured or inferred neutron star radii or core pressures, including those obtained from X-ray observations, reveals a rather satisfactory agreement. Depending on the precision that can be achieved with future measurements and observations, it will thus become possible to assess the validity of the applied models and methods. The perspectives for improved experiments at FAIR using the NeuLAND and KRAB detection systems are outlined.

15 pages, 10 figures, to appear in the AIP Conference Proceedings of the Xiamen-CUSTIPEN Workshop on the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave Astronomy (January 3 - 7, 2019, Xiamen, China)

References in corpus (24)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• GW170817: Measurements of Neutron Star Radii and Equation of State
• Neutron Star Observations: Prognosis for Equation of State Constraints
• GW170817: Joint Constraint on the Neutron Star Equation of State from Multimessenger Observations
• Neutron-star radius constraints from GW170817 and future detections
• Neutron skins and neutron stars in the multi-messenger era
• Neutron skin of 208Pb, nuclear symmetry energy, and the parity radius experiment
• A critical examination of constraints on the equation of state of dense matter obtained from GW170817
• GW170817: constraining the nuclear matter equation of state from the neutron star tidal deformability
• Results of the ASY-EOS experiment at GSI: The symmetry energy at suprasaturation density
• Constraints on the Symmetry Energy Using the Mass-Radius Relation of Neutron Stars
• Symmetry energy from elliptic flow in 197Au + 197Au
• Systematics of pion emission in heavy ion collisions in the 1A GeV regime
• Comparison of heavy-ion transport simulations: Collision integral in a box
• Extracting Nuclear Symmetry Energies at High Densities from Observations of Neutron Stars and Gravitational Waves
• Systematics of Stopping and Flow in Au+Au Collisions
• Neutron star universal relations with microscopic equations of state
• Determination of the nuclear incompressibility from the rapidity-dependent elliptic flow in heavy-ion collisions at beam energies 0.4\emph{A} - 1.0\emph{A} GeV
• Constraining the high-density nuclear symmetry energy with the transverse-momentum dependent elliptic flow
• Peeling off neutron skins from neutron-rich nuclei: Constraints on the symmetry energy from neutron-removal cross sections
• KRATTA, a versatile triple telescope array for charged reaction products
• Periodic Variations in the O-C Diagrams of Five Pulsation Frequencies of the DB White Dwarf EC 20058-5234
• Normal or abnormal isospin-fractionation as a qualitative probe of nuclear symmetry energy at supradensities
• Effects of energy conservation on equilibrium properties of hot asymmetric nuclear matter

Cited by in corpus (5)

• Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars
• GW190814's secondary component with mass $(2.50-2.67)$ M${}_{\odot }$ as a super-fast pulsar
• Bayesian Inference of the Symmetry Energy of Super-Dense Neutron-Rich Matter from Future Radius Measurements of Massive Neutron Stars
• Probing high-density nuclear symmetry energy with ${\Xi }^{-}/{\Xi }^0$ ratio in heavy-ion collisions at $\sqrt{s_{NN}}\sim 3$ GeV
• Studies of the equation-of-state of nuclear matter by heavy-ion collisions at intermediate energy in the multi-messenger era