Detectability of GRB optical afterglows with Gaia satellite

TL;DR

This study simulates Gaia satellite's ability to detect optical afterglows of gamma-ray bursts, finding limited detections for on-axis GRBs but promising prospects for orphan afterglows over five years.

Contribution

It provides the first simulation-based estimates of Gaia's detection rates for different types of GRB optical afterglows, considering satellite dynamics.

Findings

Less than 10 on-axis GRB detections expected in five years

Several tens of orphan afterglow detections possible in five years

Simulation results inform future transient detection strategies

Abstract

With the launch of Gaia satellite, detection of many different types of transient sources will be possible, one of them being optical afterglows of gamma-ray bursts (GRBs). Using the knowledge of the satellites dynamics and properties of GRB optical afterglows we performed a simulation in order to estimate an average GRB detection rate with Gaia. Here we present the simulation results for two types of GRB optical afterglows, differing in the observer's line-of-sight compared to a GRB jet axis: regular (on-axis) and orphan afterglows. Results show that for on-axis GRBs, less than 10 detections in five years of foreseen Gaia operational time are expected. The orphan afterglows simulation results are more promising, giving a more optimistic number of several tens of detections in five years.