Mysterious dark object in space
Scientists detect the lowest mass dark object currently measured
Overlay of the infrared emission (black and white) with the radio emission (colour). The dark, low-mass object is located at the gap in the bright part of the arc on the right-hand side. © Keck/EVN/GBT/VLBA Overlay of the infrared emission (black and white) with the radio emission (colour). The dark, low-mass object is located at the gap in the bright part of the arc on the right-hand side. © Keck/EVN/GBT/VLBA
To the point
Gravitational lenses: Distortions caused by gravitational lenses can be used to study the properties of dark matter, even though it does not emit light.
Distortions caused by gravitational lenses can be used to study the properties of dark matter, even though it does not emit light. Discovery: An international team has discovered a dark object in the distant universe that has one million times the mass of the Sun. The discovery is based on an analysis of the gravitational effects on the light from another galaxy.
An international team has discovered a dark object in the distant universe that has one million times the mass of the Sun. The discovery is based on an analysis of the gravitational effects on the light from another galaxy. Technology: A network of radio telescopes around the world, including the Green Bank Telescope, collected the data. It forms a virtual supertelescope that enables enhanced image quality, allowing even small gravitational signals to be detected.
Dark matter is an enigmatic form of matter not expected to emit light, yet it is essential to understanding how the rich tapestry of stars and galaxies we see in the night sky evolved. As a fundamental building block of the universe, a key question for astronomers is whether dark matter is smooth or clumpy, as this could reveal what it is made of. Since dark matter cannot be observed directly, its properties can only be determined by observing the gravitational lensing effect, whereby the light from a more distant object is distorted and deflected by the gravity of the dark object. “Hunting for dark objects that do not seem to emit any light is clearly challenging,” said Devon Powell at the Max Planck Institute for Astrophysics and lead author of the study. “Since we can’t see them directly, we instead use very distant galaxies as a backlight to look for their gravitational imprints.”
The team used a network of telescopes from around the world, including the Green Bank Telescope, the Very Long Baseline Array and the European Very Long Baseline Interferometric Network. The data from this international network were correlated at the Joint Institute for VLBI ERIC in the Netherlands, forming an Earth-sized super-telescope that could capture the subtle signals of gravitational lensing by the dark object. They found that the object has a mass that is a million times greater than that of our Sun and is located in a distant region of space, approximately 10 billion light years from Earth, when the universe was only 6.5 billion years old.
This is the lowest mass object to be found using this technique, by a factor of about 100. To achieve this level of sensitivity, the team had to create a high-fidelity image of the sky using radio telescopes located around the world. John McKean from the University of Groningen, the University of Pretoria, and the South African Radio Astronomy Observatory, who led the data collection and is the lead author of a companion paper, stated: “From the first high-resolution image, we immediately observed a narrowing in the gravitational arc, which is the tell-tale sign that we were onto something. Only another small clump of mass between us and the distant radio galaxy could cause this.”
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