Session K04: Binary Merger Simulations

Numerical Simulations of Binary Neutron Star Mergers: Gravitational Waves and Short Gamma-Ray Bursts

The discovery of GW170817 and GRB170817A showed that (at least some) short gamma-ray bursts are produced by the merger of binary neutron star (BNS) systems. I will review the current status of fully general relativistic magnetohydrodynamic (GRMHD) simulations of BNS mergers with a particular focus on the possibility of producing the relativistic jets responsible for the gamma-ray emission. I will also discuss the effects that magnetic fields may have on the post-merger gravitational-wave emission and their impact on our capability of measuring the equation of state of neutron star matter.   

New vistas in binary black holes

Our understanding of binary black hole systems has been growing in a spectacular fashion at theoretical and, since 2015, observational levels. Progress will continue to accelerate in the coming years which will further push our understanding of astrophysics and gravity itself. This talk will discuss a few successful examples on the theory/simulation front as well as challenges in the `near horizon' that should be met to enhance the scientific payoff of exciting data to come.   

Modeling kilonovae using neutron star merger simulations : current status and uncertainties

Numerical simulations of neutron star-neutron star and black hole-neutron star binaries play an important role in the interpretation of gravitational wave and electromagnetic signals from merging binaries. In this talk, I will first provide a broad overview of current simulations of black hole-neutron star binaries, and of the challenges that we face to bring these simulations to the level of accuracy and physical detail required to reliably extract information from merger observations in the Advanced LIGO/Virgo era. I will then look in more detail at the modeling of kilonovae, the bright optical/infrared emission that follows neutron star mergers. I will in particular focus on the impact of neutrino transport on the properties of kilonovae. I will discuss the strength and limitations of the algorithms currently used to model neutrino transport, the impact of these limitations on kilonova modeling, and some promising way forward to improve on the current state-of-the art for neutrino transport in merger simulations.