Probing neutron-star matter in the lab: connecting binary mergers to heavy-ion collisions

Abstract

As a way to find analogies and differences in the dynamics of hot and dense matter under extreme conditions, we present the first self-consistent relativistic-hydrodynamic calculations of both neutron-star mergers and lowenergy heavy-ion collisions employing the same equation of state. By a direct comparison of the evolution of quantities such as temperature, entropy, and density, we show that neutron-star collision regimes can be probed directly at GSI beam energies. We provide concrete evidence that the physical conditions reached in binary neutron-star mergers can be studied in present and future laboratory experiments, thus bridging 18 orders of magnitude in length scale, from microscopic ion collisions to macroscopic astrophysical compact objects.

The Role of the Hadron-Quark Phase Transition in Core-Collapse Supernovae

“…The smooth nature of the crossover from hadrons to quarks does not lead to a third family branch of compact stars. All these components allow the CMF model to be applied for modeling of heavy-ion collisions (Steinheimer et al 2010;Omana Kuttan et al 2022), analysis of lattice QCD data , 2014Motornenko et al 2020Motornenko et al , 2021aMotornenko et al 2021b), as well as studies of cold neutron stars and their mergers (Most et al 2022). Since the CMF EoS does not include heavy nuclei at sub-saturation density, we extend it to low densities using the SFHx EoS (Steiner et al 2013), which is matched to the CMF table at densities less than 8 × 10 13 g cm −3 .…”

“…Since the CMF EoS does not include heavy nuclei at sub-saturation density, we extend it to low densities using the SFHx EoS (Steiner et al 2013), which is matched to the CMF table at densities less than 8 × 10 13 g cm −3 . Note that the CMF model with a similar matching has been recently applied to describe the dynamical evolution of binary neutron star mergers as well as heavy ion collisions at the SIS18 accelerator (Most et al 2022).…”

“…We note in passing that the high specific entropies reached in the PCS due to inverted mixing are significantly larger than those reached in a recent study on simulating 6 The Clausius-Clapeyron relation (Landau & Lifshitz 1980) is often referenced for the negative pressure gradient d𝑃 d𝑇 for Maxwellian phase transitions (local charge neutrality during the mixed phase) where pressure in the mixed phase is independent of density which is not the case for a Gibbs construction. heavy ion collisions and binary neutron star mergers using the same underlying CMF EoS we used (Most et al 2022).…”

“…The order of the phase transition at finite densities is, however, not yet fully understood (Annala et al 2020;Cuteri et al 2021). With the advancement of multi-messenger astronomy (Abbott et al 2017;Aartsen et al 2017), astrophysical observations have the potential to further constrain the EoS in the QCD regime as the physical conditions in relativistic heavy-ion collisions are closely linked, e.g., to those in neutron star mergers (Hades Collaboration et al 2019;Hanauske et al 2017;Hanauske et al 2019;Most et al 2022). The extreme environment at the centre of PCSs can exceed densities of 𝜌 centre 10 15 g cm −3 with maximum temperatures of the order 10 12 K. Phenomenological models are the basis on which predictions about the phase transition from hadrons to quarks rely in these intermediate regimes of the QCD phase diagram.…”

Exotic Cores with and without Dark-Matter Admixtures in Compact Stars

“…We emphasize the relation of ultra-relativistic heavy-ion collision physics, related to the EoS p(T, µ B ≈ 0), and compact star physics, related to p(T ≈ 0, µ B ) when focusing on static compact-star properties [49,50]. (Of course, in binary or ternary compact-star merging-events, also finite temperatures T and a large range of baryon-chemical potential µ B are probed [51].)…”