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MeV Gamma-ray Astronomy in the 2020s and Beyond

Current and Future European Missions Focusing on GRBs

Rachel Dunwoody


A breakthrough discovery was made with the coincident detection of GW170817/GRB170817A marking the beginning of a new era of multimessenger astronomy. The gravitational wave (GW) instrument advancements made between observing runs, with the third observing run expected to commence in 2023, has highlighted the demand for instrumentation to detect the gamma-ray burst (GRB) counterparts to GW events. The two currently operational large-scale missions in Europe, INTEGRAL and AGILE, have exceeded their nominal mission lifetimes. Future large-scale missions including SVOM, a Franco-Chinese mission due for launch in mid 2023, cannot provide full sky coverage. THESEUS, one contender for a future large-scale gamma-ray mission has been selected for further study for the European Space Agency's M7 mission opportunity. The science case of Athena, not due for launch until the 2030s, also includes GRBs as tools to study the WHIM (warm hot intergalactic medium), however, due to programmatic constraints, the mission is currently being rescoped. These large missions take years to develop meaning alternatives need to be considered to bridge the gap and assist global current missions that are past their nominal phase e.g. NASA Fermi, ESA INTEGRAL, NASA Swift.

Small satellites, with mass < 180 kg, provide an opportunity to demonstrate novel gamma-ray detection technology on short cost and project timescales, vital aspects when considering the upcoming GW observational runs. There are a number of European groups developing and launching instruments on CubeSats for observing GRBs. EIRSAT-1, an Irish CubeSat, has a <1U GRB detector on board. EIRSAT-1 is a stepping stone to a larger mission with detection and localisation capabilities, joining a collection of other small-scale missions (e.g. GRBAlpha, HERMES) to assist current missions with all-sky coverage and bridge the gap until future large-scale missions with the goal of detecting GRBs are developed and launched.