BlackGEM telescopes begin searching for sources of gravitational waves

Some cataclysmic events that take place in the universe, such as the collision of black holes or neutron stars, create gravitational waves. These are ripples in the fabric of time and space. Observatories such as LIGO (Laser Interferometer Gravitational-Wave Observatory, Laser Interferometer Gravitational Wave Observatory) and the Virgo interferometer are designed to detect these disturbances. But they can’t pinpoint its origin very precisely or see the fleeting glow that results from collisions between neutron stars and black holes.

The BlackGEM set, made up of three new telescopes located at the La Silla Observatory, dependent on the European Southern Observatory (ESO), has begun its activity to detect this. The telescopes will monitor the southern hemisphere sky for cosmic events that produce gravitational waves, such as neutron star and black hole mergers. BlackGEM uses visible light to quickly scan large areas of the sky to accurately capture sources of gravitational waves.

“With BlackGEM we intend to extend the study of these cosmic events using both gravitational waves and visible light,” says Paul Groot of the University of Radboud in the Netherlands, principal investigator of the project. “The combination of both gives us much more information about these events than studying just one of them.”

By detecting both gravitational waves and their visible counterparts, the astronomical community can confirm the nature of gravitational wave sources and accurately determine their locations. The use of visible light also allows for detailed observations of the processes that occur in these mergers, such as the formation of heavy elements such as gold and platinum.

To date, however, only a visible counterpart to a gravitational wave source has been detected. Furthermore, even the most advanced gravitational wave detectors, such as LIGO or Virgo, cannot accurately identify their sources of origin. At best, they can narrow a source’s location to an area of ​​about 400 full moons in the sky. Using visible light, BlackGEM will efficiently scan such large regions at a resolution high enough to systematically locate sources of gravitational waves.

The three telescopes that make up BlackGEM were built by a consortium of universities: Radboud University, the Netherlands Research School of Astronomy, and the University of Leuven in Belgium. The telescopes are each 65 centimeters in diameter and can study different areas of the sky simultaneously. The collaboration ultimately aims to expand the array to 15 telescopes, further improving its scanning coverage. BlackGEM is located at ESO’s La Silla Observatory in Chile, making it the first array of its kind in the southern hemisphere.

“Despite the modest 65-centimeter primary mirror, we reached the same depth as other projects with much larger mirrors, as we took full advantage of the excellent viewing conditions at La Silla,” says Groot.

A night view of the BlackGEM ensemble at ESO’s La Silla Observatory. (Photo: IT)

Once BlackGEM accurately identifies a source of gravitational waves, larger telescopes such as ESO’s Very Large Telescope (VLT) or the future Extremely Large Telescope (ELT) can carry out detailed follow-up observations, which will help clarify some of the most extreme events in the cosmos.

In addition to its search for the optical counterparts of gravitational waves, BlackGEM will also conduct surveys of the southern sky. Its operations are fully automated, meaning the array can quickly find and observe “transient” astronomical events, which appear suddenly and fade quickly. This will give the astronomical community deeper insight into short-lived astronomical phenomena such as supernovae, the huge explosions that mark the end of a massive star’s life.

“Thanks to BlackGEM, La Silla now has the potential to make an important contribution to the investigation of transient phenomena,” says Ivo Saviane, manager of ESO’s La Silla Observatory. “We hope that this project will deliver many outstanding results, which will broaden the impact of the observatory for both the scientific community and the general public.”

The BlackGEM consortium also includes, among other institutions, the University of Valparaíso in Chile and the University of Barcelona. (Source: IT. CC BY 4.0)