DOI

https://doi.org/10.48717/8s4t-1t85

Project

GG084

Title

BNS merger counterpart

Abstract

We propose to observe the first ever counterpart (SSS17a/DLT17ck) of the first ever merger of two neutron stars detected by LIGO/Virgo (GW170817A). Through a clear-cut Global VLBI observation we will be able to answer the fundamental question whether (or not) a relativistic jet was launched in the process of the NS-NS merger. A relativistic jet, even if misaligned, would reach a flux density ~0.1-1 mJy at 5 GHz in the next months. A non detection would support jet-less scenarios. Moreover, late time VLBI observations are fundamental to constrain, together with available data that will be published in October this year, the physical parameters of the outflow (e.g. mass-energy content, bulk velocity, opening angle and orientation in the sky). Global VLBI angular resolution, while being fundamental to properly account for the contamination by the host galaxy core - 10 arcsec away, will allow us to measure the source size expected to reach mas angular scales at the time of the proposed observations. Size and flux density measurements provide us the unique opportunity to measure the energetic of the jet and the density of the ambient medium.