A brand new telescope array has begun to hunt for essentially the most violent and cataclysmic events within the cosmos, clashes so powerful that they cause the very fabric of space and time to “ring.”
The BlackGEM array, consisting of three latest telescopes positioned on the European Southern Observatory’s (ESO) La Silla Observatory in Chile, will search in visible light for events like neutron star collisions and black hole mergers, which launch ripples in space-time called gravitational waves.
“With BlackGEM, we aim to scale up the study of cosmic events with each gravitational waves and visual light,” BlackGEM Principal Investigator Paul Groot, of Radboud University within the Netherlands, said in an announcement (opens in latest tab). “The mix of the 2 tells us way more about these events than simply one or the opposite.”
To this point, just one explosive event has been detected in each gravitational waves and visual light, the collision between two neutron stars with masses between eight and 20 times that of the sun, which occurred 130 million years ago.
By detecting each the gravitational waves and visual light generated by such events, scientists cannot only hone in on their precise locations but may learn more about their nature. For instance, astronomers could confirm that collisions between neutron stars, also often called kilonovas, do indeed forge heavy elements like silver, platinum, and gold, as suspected.
Following up ripples in space-time predicted by Einstein
Gravitational waves were first predicted by Albert Einstein in his theory of general relativity. This 1915 theory says that objects of mass “warp” the material of space-time, a four-dimensional unification of space and time, like objects placed on a stretched rubber sheet. This warping gives rise to gravity. General relativity also suggests that when massive objects speed up, they generate gravitational waves.
Objects of tremendous mass circling one another, like binaries of black holes and neutron stars, produce gravitational waves that carry angular momentum away from the system, causing them to spiral together faster and faster. When the 2 objects finally collide and merge, they create a burst of gravitational waves that could be detected from Earth, even after traversing thousands and thousands or billions of light-years on the speed of sunshine to achieve us.
The primary detection of gravitational waves was made on Earth in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and got here from the collision of two black holes 1.3 billion years ago. Since then, LIGO, based within the U.S., and its fellow gravitational wave detectors Virgo in Italy and KAGRA in Japan have detected gravitational waves from other black hole mergers, neutron star mergers and even collisions between black holes and neutron stars (that are the super-dense corpses of massive stars).
As impressive as that is, nonetheless, gravitational wave detectors cannot accurately pinpoint the placement from which gravitational waves originate. Nor can they see the energetic blasts of sunshine which can be emitted with the gravitational wave bursts that occur during these collisions.
That is where BlackGEM will are available, quickly scanning large areas of the sky to hunt for gravitational-wave sources in visible light and more accurately honing in on their locations.
How BlackGEM will slot in
Once BlackGEM identifies the source of gravitational waves, larger instruments just like the Very Large Telescope (VLT) positioned on Cerro Paranal within the Atacama Desert of northern Chile will follow up on its findings by zooming in on the event.
The three telescopes of the BlackGEM array are each 25.6 inches (65 centimeters) in diameter and might investigate different areas of the sky concurrently. Eventually, these telescopes, built by Radboud University, the Netherlands Research School for Astronomy and KU Leuven in Belgium, could also be joined within the array by an extra 15 scopes.
This could give a powerful boost to the sky-searching power of the BlackGEM array, the primary system of its kind within the Southern Hemisphere.
“Despite the modest 65-centimeter primary mirror, we go as deep as some projects with much larger mirrors because we take full advantage of the wonderful observing conditions at La Silla,” Groot said.
BlackGEM won’t just be trying to find the sources of gravitational waves, nonetheless. The telescope array can even survey the southern sky in fully automated mode, allowing it to quickly find and discover events and objects with rapidly changing brightness, also often called “transients.”
These could include supernovas, titanic explosions that accompany the deaths of massive stars after which quickly fade from view.
“Due to BlackGEM, La Silla now has the potential to turn into a serious contributor to transient research,” La Silla Observatory site manager Ivo Saviane said. “We expect to see many outstanding results contributed by this project, which can expand the reach of the location for each the scientific community and the general public at large.”