The project

The first gravitational wave (GW) and electromagnetic (EM) observation of a merging binary neutron star (BNS) system in 2017 opened the era of multimessenger astronomy with GW sources and confirmed the central role of BNS mergers in present-day astrophysics and fundamental physics. This event proved that such systems can launch relativistic jets and power short gamma-ray bursts (GRBs), which are among the most energetic phenomena in the Universe. Additionally, they can produce a copious amount of heavy elements through r-process nucleosynthesis. Moreover, the combination of GW and EM signals led to new constraints on the neutron star equation of state, encoding the behavior of supranuclear matter, and on the Hubble constant. 

While this was a major breakthrough, the most revealing aspects of the underlying physical scenario remain uncertain, from the post-merger dynamics and the nature of the remnant object to the mechanisms behind jet formation and matter ejection. In order to draw a clear and consistent picture of this kind of events, which is the only way to fully exploit the rich information they can provide, we urgently need a substantial quality step in our BNS merger models and simulations.

The goal of the EMERGE project is to improve our ability to simulate BNS mergers and describe the involved physical processes that directly connect with the rich variety of signals expected from these events. Thanks to the inclusion of key ingredients like magnetic fields and neutrino radiation, combined together with treatments beyond the present state of the art, we have the opportunity to investigate with a high degree of realism the post-merger dynamics and the associated GW emission, mass ejection, r-process nucleosynthesis, and jet formation. Moreover, a direct connection with larger scale jet simulations and kilonova emission models, recently accomplished by our team, enable us to link the properties of the merging system with those of the escaping jet and the expected kilonova signal. Our description allows us to gain new insights into long-standing open issues like, e.g., the identification of the GRB jet launching mechanism in BNS merger context and the nature of central engine. The scientific impact of the project is rather broad, touching a variety of research fields across nuclear, high-energy, and multimessenger astrophysics.