G17C001

Do binary neutron star mergers always produce a jet?

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.

Investigators

Name	Institution
GBT Operator	Green Bank Observatory
Giancarlo Ghirlanda *	Brera, Osservatorio Astronomico di
Marcello Giroletti	Istituto Nazionale di Astrofisica
Gabriele Ghisellini	Brera, Osservatorio Astronomico di
Zsolt Paragi	Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium
Ivan Agudo	Boston University; Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium; Andalucía, Instituto de Astrofísica de; Andalucía, Instituto de Astrofísica de
Rob Beswick	Manchester, University of
Carolina Casadio	Andalucía, Instituto de Astrofísica de; Max-Planck-Institut für Radioastronomie; Foundation for Research & Technology - Hellas
Valerio D'Elia	Istituto Nazionale di Astrofisica
Sandor Frey	Konkoly Observatory of the Hungarian Academy of Sciences
Peter Jonker	Center for Astrophysics | Harvard & Smithsonian
Benito Marcote	Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium
Javier Moldon	Manchester, University of; Andalucía, Instituto de Astrofísica de; Barcelona, Universitat de
Arpad Szomoru	Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium
Tao An	Shanghai Astronomical Observatory, CAS
Jun Yang	Shanghai Astronomical Observatory, CAS
Huib van Langevelde	Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium; Leiden, University of

* indicates the PI