3U Transat: a cubesat constellation to boost the multi-messenger astronomy

Abstract: Thanks to the advent of sensitive gravitational wave (GW) and neutrino detectors, multi-messenger (MM) astronomy will deeply transform our understanding of the Universe contents and evolution over cosmological times. To fully exploit the forthcoming GW and neutrino discoveries, it is crucial to detect as many electromagnetic (EM) counterparts as possible, but up to now, only one event has been detected by both GW detectors (Ligo/Virgo) and electromagnetic detectors (Fermi/GBM (Gamma ray Burst Monitor) and Integral), the short gamma-ray burst GRB 170817A/GW 170817 associated with the merger of a binary neutron star. To help improving the rate of joint MM events, it is crucial for the EM detectors in particular at high-energy in space to observe all the sky with a decent sensitivity. To do so, we propose the development of 3U Transat (TRANsient sky SATellites) project. 3U Transat is a constellation of nano-satellites offering a full sky coverage with a limited investment. The goal of this article is to present the 3U Transat project and its main scientific drivers as well as its current status. We will also describe our dynamic simulator used to optimise the scientific performances of the constellation. We will show highlights of the expected performances in term of detection and localisation capabilities as a function of the number of satellites in the constellation.