Revealing Short GRB Jet Structure and Dynamics with Gravitational Wave Electromagnetic Counterparts

TL;DR

This paper explores how gravitational wave detections of compact mergers can be used to study short gamma-ray burst jets, revealing their structure, dynamics, and potential hidden populations through electromagnetic counterparts.

Contribution

It models EM afterglows from various jet structures and viewing angles to predict observable features, aiding in constraining jet properties using GW-EM observations.

Findings

Predicted EM signatures for different jet structures and viewing angles.

Identified potential for GW-triggered searches to find orphan afterglows.

Provided observational indicators for jet structure models.

Abstract

Compact object mergers are promising candidates for the progenitor system of short gamma-ray bursts (GRBs). Using gravitational wave (GW) triggers to identify a merger, any electromagnetic (EM) counterparts from the jet can be used to constrain the dynamics and structure of short GRB jets. GW triggered searches could reveal a hidden population of optical transients associated with the short-lived jets from the merger object. If the population of merger-jets is dominated by low-Lorentz-factors, then a GW triggered search will reveal the on-axis orphan afterglows from these failed GRBs. By considering the EM counterparts from a jet, with or without the prompt GRB, the jet structure and dynamics can be constrained. By modelling the afterglow of various jet structures with viewing angle, we provide observable predictions for the on- and off- axis EM jet counterparts. The predictions provide an indication for the various features expected from the proposed jet structure models.