Speaker: Taya Govreen-Segal (Department of Astrophysics, School of Physics & Astronomy, Tel-Aviv University)

Title: The hydrodynamic evolution of jetted blast waves - implications for gamma-ray bursts

Abstract:
Gravitational wave (GW) events accompanied by an observable jet provide a unique opportunity to study GRB jets. The geometry of these jets is of special interest. The jet core angle and jet structure are related to its total energy, propagation, and launching mechanism, while the observing angle can significantly improve the accuracy of the measurement of H0 using GW.  However, while the jet observing angle is constant, the jet core angle and structure evolve throughout its evolution, and understanding this evolution is necessary if we want to measure the initial core angle and jet structure.
A unique property of mergers detected by their GW signal (unlike those detected by their GRB prompt emission) is that they are nearby, and the jets are seen off-axis. This combination presents a special opportunity to measure the system geometry. High-resolution radio observations that can resolve the motion of the GRB afterglow images play a key role in decoding the jet geometry. In my talk, I will present a detailed analytical and numerical study of the jets’ fluid dynamical evolution and show that many jets approach a self-similar solution, while still retaining memory of their initial conditions. I will discuss the implications of the jets’ structure evolution on the observed light curve and afterglow image, and on our ability to measure the jets' initial structure and core angle. And, time permitting, say a few words about measuring H0 with a small number of gravitational wave events with an observable jet.

Zoom link:
https://huji.zoom.us/j/83921534992?pwd=Iy5HjZU7mwAHTHzSKb3LXkcfkSpRAq.1
Meeting ID: 839 2153 4992
Passcode: 752528
 
Contact: Dima Ofengeim