The gravitational wave follow-up program of the Cherenkov Telescope Array
2019 July 22
The birth of gravitational-wave / electromagnetic astronomy was heralded by the joint observation of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo, GW170817, and of gamma-rays from the short gamma-ray burst GRB170817A by the Fermi Gamma-ray Burst Monitor (GBM) and INTEGRAL. This detection provided the first direct evidence that at least a fraction of BNSs are progenitors of short GRBs. GRBs are now also known to emit very-high-energy (VHE, > 100 GeV) photons as has been shown by recent independent detections of the GRBs 1901114C and 180720B by the ground-based gamma-ray de- tectors MAGIC and H.E.S.S. In the next years, the Cherenkov Telescope Array (CTA) will boost the searches for VHE counterparts thanks to its unprecedented sensitivity, rapid response and ca- pability to monitor large sky areas via survey-mode operation. In this contribution, we present the CTA program of observations following the detection of GW events. We discuss various follow- up strategies and links to multi-wavelength and multi-messenger observations. Finally we outline the capabilities and prospects of detecting VHE emission from GW counterparts.