The recent GW+EM detection of a neutron star merger has underlined the multitude of physical processes that are needed for a reliable prediction of multi-messenger signals. In the talk I will discuss the various processes that lead from the merger to the electromagnetic emission. Particular attention will be payed to topics where our understanding is incomplete and more progress is needed.
A robust and quantitative understanding of neutron star mergers requires detailed numerical simulations. The latter must include all the relevant physics, resolve the necessary lenght scales, and cover all the important temporal phases. The key role of all fundamental interactions makes this task extremely challenging. In this talk, I will briefly summarize the present status of the field and...
I will present results of general relativistic hydrodynamic (GRHD) simulations of binary neutron star (BNS) mergers with a hybrid leakage-transport scheme for the neutrino treatment. I will discuss the matter dynamics and show the thermodynamic conditions of the fluid in the region where the three evolved neutrino species decouple from matter. Finally, I will give an overview of the...
We present FO-CCZ4, a strongly hyperbolic first-order formulation of the Einstein
equations based on the conformal and covariant Z4 system with constraint-violation damping. This formulation combines the advantages of a conformal and traceless formulation, with the suppression of constraint violations given by the damping terms, but being first order in time and space, it is particularly...
With the detection of GW170817 we have observed the first multi messenger signal from two merging neutron stars.
This signal carried a multitude of information about the underlying equation of state (EOS) of nuclear matter, which so far is not known for densities above nuclear saturation. In particular it is not known if exotic states or even a phase transition to quark matter can occur at...
Neutron star merger is a unique cosmic laboratory to investigate general relativity in a strong field regime and fundamental physics, including dense matter and heavy-elements-nucleosynthesis.
Our work focuses on the electromagnetic counterpart of the gravitational wave source GW170817. We study the merger dynamics and light curves employing the state of the art numerical, general...
Merging neutron stars are both gravitational wave and electromagnetic transient sources, as confirmed by the detection of the GW170817 event. The gravitational wave emission was indeed followed by emission all across the electromagnetic spectrum, including an optical and infrared signal known as macronova. This signal is powered by the radioactive decay of freshly synthesized r-process...
The astrophysical production site of the heaviest elements in the universe remains a mystery. Incorporating heavy element signatures of metal-poor, r-process enhanced stars into theoretical studies of r-process-process production can offer crucial constraints on the origin of heavy elements. In this study, we apply the "Actinide-Dilution with Matching" model to a variety of...
