VLBA17B-400

Imaging the Fireball of the Nearest Binary Neutron Star Merger Event

Abstract

On August 17, 2017, the Advanced LIGO and Advanced VIRGO observatories detected the gravitational wave signal GW170817 from a binary neutron star merger. Just twelve hours after this discovery, a multi-observatory follow-up campaign found a bright optical counterpart (EM170817), and on September 03 our team discovered the radio afterglow of GW170817 with the VLA. Using further radio follow up observations along with optical and X-ray data, we were able to constrain the possible afterglow emission mechanism to two models: the conventional off-axis relativistic jet and a low-energy cocoon model, both of which predict that the source has peaked, or will peak shortly. Although EM170817 is very faint in the radio, it is still possible to detect resolved structure with the High Sensitivity Array. We propose simultaneous observations with the VLBA, GBT and VLA27 in L band over three epochs. With our proposed program, we will be able to establish the size and geometry of the radio source, thus providing direct observational constraints on the ejecta velocity and the nature of the afterglow.

Investigators

Name	Institution
Adam Deller	Swinburne University of Technology
Stephen Bourke	Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium; Galway, National University of Ireland; Chalmers University of Technology; California Institute of Technology
Ehud Nakar	Tel Aviv University
Assaf Horesh	Weizmann Institute of Science; Jerusalem, Hebrew University of; California Institute of Technology
Dale Frail	National Radio Astronomy Observatory
Kenta Hotokezaka	Princeton University; Tokyo, University of; Jerusalem, Hebrew University of
Gregg Hallinan	National Radio Astronomy Observatory; California at Berkeley, University of; California Institute of Technology
Kunal Mooley *	National Radio Astronomy Observatory; California Institute of Technology
GBT Operator	Green Bank Observatory

* indicates the PI