Dark Cosmic Object Found By Astronomers Raises Questions About The Universe
by
Aaron Leong
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Friday, October 10, 2025, 10:07 AM EDT
With the aid of a multinational network of radio telescopes, scientists have been able to detect the lowest-mass dark object ever found in the universe. The mysterious object, roughly one million times the mass of our Sun (approximately 10 billion light-years from Earth) was discovered using gravitational imaging to spot a subtle warp of spacetime.
Published in Nature Astronomy last week, the discovery provides a critical new test for the widely-accepted Cold Dark Matter (CDM) theory, which predicts that dark matter forms clumps, or halos, across a vast range of sizes. Since dark matter does not emit or reflect light, it can only be detected by its gravitational influence on visible objects. Astronomers found the object by observing the JVAS B1938+666 galaxy, where the light from a background galaxy is gravitationally lensed by a foreground galaxy, creating a large, distorted arc of light.
A zoom-in of the main image shows the pinch in the luminous radio arc, where the extra mass from the dark object is gravitationally imaged. The dark object is indicated by the white blob at the pinch point of the arc. (Credit: Keck/EVN/GBT/VLBA)
Within this arc the team found a tiny, distinct pinch or aberration (above). This subtle flaw in the image could only be explained by the presence of an additional, much smaller, invisible mass clump acting as a secondary gravitational lens. By mapping this distortion using radio telescopes from the Green Bank Telescope, the Very Long Baseline Array, and European Very Long Baseline Interferometric Network, the team successfully imaged the dark object's gravitational field. Doing so allowed them to measure its mass at nearly 100 times smaller than any dark matter clump previously measured at such a distance.
While the detection is a triumph for gravitational imaging, the true nature of the million-solar-mass object remains unknown. The two leading possibilities are:
A clump of dark matter: a starless, invisible concentration of the mysterious substance that makes up about 27% of the universe's total mass. If confirmed, this object would be the smallest, most distant dark matter halo ever detected, which could align it with the predictions of the CDM model.
A very compact, inactive dwarf galaxy: a small galaxy that contains very few stars, making it almost completely dark.
Nonetheless, the ability to detect such low-mass objects at this distance is mightily impressive, while proving that gravitational imaging is a viable tool for this kind of research. As researchers probe the skies, there's also a possibility that they may find that objects of this size are rarer than what CDM predicts, necessitating a shift towards alternative theories such as Modified Newtonian Dynamics and Superfluid Dark Matter.
