When neutron stars and black holes collide, gravitational waves are released and a hot luminous ring of gas is created. These waves are detected on earth by laser interferometers like LIGO and Virgo. However, it is difficult to determine exactly where these types of collisions occurred. LIGO and Virgo can only determine the location within an area that is 400 times as big as the surface of the full moon.
BlackGEM is a series of three telescopes that has been designed to detect the optical radiation from colliding neutron stars and black holes. BlackGEM is fast, it spans a vast area and it is sensitive enough to locate the light that has been created in the collision within the search area specified by LIGO and Virgo. The telescopes start by creating a highly detailed colour map of the southern sky, and then compare the new observations so that they can find the light from the new source.
Their main purpose is to determine the exact location of the collision. The brightness, colour of the source and the subsequent observations with other telescopes will tell the researchers where the collision took place, how it occurred, how much gas was emitted, which nuclear reactions took place and what the chemical composition of the gas is.
The telescopes were developed and built at Radboud University, NOVA and KU Leuven, and have been installed at ESO’s La Silla Observatory in Chile. A prototype has been installed in South Africa and remains operational.