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We present synthetic radio images of the GRB170817A afterglow, computed frommoving-mesh hydrodynamic simulations of binary neutron star merger outflows.Having expanded for nearly a year, the merger remnant is expected to subtendroughly 5 milli-arcseconds (mas) on the sky, potentially resolvable by verylong baseline radio imaging techniques. Any observations revealing the radiocentroid to be offset from the line-of-site to the merger would be the smokinggun of a jetted outflow. However, our results indicate that a measurement ofthe centroid position alone cannot independently determine whether that jetescaped successfully from the merger debris cloud, or was "choked," yielding aquasi-spherical explosion. We find that in both scenarios, the centroidexhibits superluminal proper motion away from the merger site at roughly 4 - 10mas per day for at least the first 300 days. We argue that a successfulstrategy for differentiating among the explosion models will need to includemultiple observations over the coming months - years. In particular, we findthe time at which the centroid attains its maximum offset, and begins headingback toward the merger site, is considerably later if the jet was choked.Detecting a reversal of the centroid trajectory earlier than 600 days woulduniquely identify a successful jet. Our results indicate the source might beresolved using VLBI radio observing techniques with roughly 1 mas resolutionstarting at roughly 400 days post-merger, and that the the angular extent of asuccessful jet is significantly smaller than that of a choked jet (4.5 versus 7mas respectively).

Radio sky maps of the GRB 170817A afterglow from simulations