Session L4: Invited Session: Challenges in Numerical Relativity

Numerical Relativity and Black Hole Binaries: The historical path to present simulations

The numerical relativity landscape at the turn of the century reached a unique transformative moment. A time with the ripe conditions to solve one of the grand challenges in computational physics: the two-body problem in general relativity. The computational modeling of two black holes as they coalesce is a formidable undertaking, requiring the most powerful hardware, innovative algorithms and creativity. This talk provides a historical perspective of the developments that led to the current success we enjoy of binary black hole simulations as genuine tools of discovery in the new astronomy of gravitational waves.   

Computing EM signatures from astrophysical compact binary mergers

In the next few years the new generation of gravitational wave detectors will likely detect some of the most energetics events in the universe; the coalescence and merger of binary compact objects, which will help to test gravity in the strong field regime. If the magnetic field is sufficiently strong, the binary may produce a detectable electromagnetic burst, especially if it is in the form of a jet. The concurrent detection of EM and GW signals (and possibly neutrinos) will open the door to the so-called multimessenger astronomy, which can confirm the detection and give more insight into the physical processes involved. I will describe some of the numerical evolutions involving black holes and neutron stars binaries, focusing on the GW waveforms, the possible EM counterparts and its astrophysical implications.   

Simulation of Core Collapse Supernovae

One of the most interesting open problems in modern astrophysics is the origin of the chemical elements of which we and the planet we live are made. We know now that most of the heavy elements (i.e., heavier than Iron) are produced in core collapse supernova explosions (CCSN). These explosions mark the end of the lives of stars with masses in the range of ten to a few dozens solar masses and they still carry mysteries very hard to unravel. Chief of them is the mechanism by which the explosion itself occurs. Simulating CCSN is one of the hardest challenges in numerical astrophysics and despite of decades of work and great progress, the physical processes that fuel the explosion are not yet fully understood. To complicate matters, the astronomical observations of CCSN are mostly confined to electromagnetic signatures that provide information on processes occurring at the explosions outer boundaries since the core is deeply shrouded in opaque material. Fortunately, CCSN are among the sources that will produce gravitational waves (GW) detectable by GW observatories around the globe. In particular, a Galactic supernova event will likely produce a signal well within the Advanced version of the ground-based GW observatories across a broad range of frequencies. Comparisons of GW signals with numerical models could settle many questions about the origin and evolution of CCSN. This talk will cover some of the latest simulations of CCSN with particular emphasis in the generation of long term GW (i.e., covering about the first second of the explosions) and the numerical challenges they face currently and in the road ahead.