Exploring Short-GRB afterglow parameter space for observations in coincidence with gravitational waves

TL;DR

This paper investigates how gravitational wave detections of neutron star mergers can inform and constrain the physical parameters of short gamma-ray burst afterglows across multiple electromagnetic frequencies, enhancing multi-messenger astronomy.

Contribution

It provides a simulation-based analysis of the afterglow parameter space in the context of GW-EM coincident observations, identifying regions leading to different detection outcomes.

Findings

Narrowed down afterglow parameter regions for detection scenarios.

Identified how detection or non-detection constrains afterglow physics.

Provided insights into multi-messenger observational strategies.

Abstract

Short duration Gamma Ray Bursts(SGRB) and their afterglows are among the most promising electro-magnetic (EM) counterparts of Neutron Star (NS) mergers. The afterglow emission is broadband, visible across the entire electro-magnetic window from $\gamma$-ray to radio frequencies. The flux evolution in these frequencies is sensitive to the multi-dimensional afterglow physical parameter space. Observations of gravitational wave (GW) from BNS mergers in spatial and temporal coincidence with SGRB and associated afterglows can provide valuable constraints on afterglow physics. We run simulations of GW-detected BNS events and assuming all of them are associated with a GRB jet which also produces an afterglow, investigate how detections or non-detections in X-ray, optical and radio frequencies can be influenced by the parameter space. We narrow-down the regions of afterglow parameter space for a uniform top-hat jet model which would result in different detection scenarios. We list inferences which can be drawn on the physics of GRB afterglows from multi-messenger astronomy with coincident GW-EM observations.