Astronomy & Astrophysics Seminar: Relativistic outflows in Collapsars & Neutron star mergers

Zoom: https://zoom.us/j/7365745304

Abstract:

Following a collapse of a massive star/Neutron star merger (NSM), a relativistic jet is launched into the dense stellar/ejecta material. During the jet propagation in the dense medium, matter is pushed around the jet to form a hot cocoon which applies pressure on the jet and potentially collimates it. The jet and the cocoon eventually break out from the dense medium and emit radiation: The jet generates beamed GRB and afterglow emissions, while the cocoon expands and emits radiation over large angles throughout the entire electromagnetic spectrum. Using 3D relativistic hydrodynamic simulations I will discuss the emission mechanisms from the jet-cocoon system. First, I will show how hydrodynamic processes shape the jet-cocoon morphology and whether the resulting emission from the photosphere or internal shocks can account for the GRB powering mechanism.  Then, I will address the emission from relativistic outflows in NSMs, from the first seconds to years later, and compare it with GW170817 observables. I will conclude with what we can expect from electromagnetic signals in future NSM events.

Seminar Organizer: Dr. Omer Bromberg