Weighing a Million Suns: Smallest ‘Dark Matter Object’ Discovered in the Universe

Lebanon Today

On a quiet night on planet Earth, astronomers weren’t looking to the sky for a new star, but were hunting for a shadow in the heart of the universe, a dark object, neither seen nor lit, revealing itself only through its subtle effect on light.

From Germany to the United States and South Africa, a team of scientists gathered around a massive network of radio telescopes, stretching from the Green Bank Telescope in West Virginia to the European Very Long Baseline Interferometry Network, whose telescopes connect across several continents, turning the Earth itself into a giant telescope searching for a single signal: a small bend of light amidst a sea of stars.

Strange Objects: “Dark objects” do not emit any light or radiation, but their existence is detected through the effect of their gravity on light coming from distant objects, in a phenomenon known as “gravitational lensing,” where gravity distorts the path of light passing near the invisible object, causing a bulge in the image distorted by a larger object, resembling a small defect in a house of mirrors.

In reality, scientists do not yet know exactly what these objects are. They are neither stars nor clear galaxies as we know them, but lie in a mysterious area between the two. Some scientists believe they are clumps or “nodes” of dark matter that do not contain stars or gases, so they do not emit any light.

Another team of scientists expects them to be dormant dwarf galaxies that have lost their gas and active stars, and their cores may consist of black holes or extinguished star clusters.

Sign of Dark Matter: As scientists stared into their telescopes, the sign they were waiting for suddenly appeared: a subtle bulge in a distant light image, as if the mirror of the universe itself had an unexpected scratch.

This bulge was not a measurement error, but the fingerprint of an unknown dark object, the smallest of its kind ever discovered, with a mass estimated at about a million times the mass of the Sun, and located about 10 billion light-years from Earth.

Professor Chris Fassnacht of the University of California, Davis, and a participant in the study, said in an official statement published on the university’s website that “being able to spot an object of such small mass at such a huge distance is an amazing achievement, as each object of this kind brings us one step closer to understanding the nature of dark matter.”

He adds that “the analysis showed that this mysterious object has a mass of about a million times the mass of the Sun, but it does not resemble anything known, it may be a mass of dark matter that makes up a quarter of the universe and is not seen, or perhaps a dead dwarf galaxy whose stars have faded long ago.”

Confirming the “Cold Dark Matter” theory: This discovered object is the least massive object discovered using the “gravitational lensing” technique, suggesting that it can be used to discover more similar dark objects in the future.

Lead researcher Devon Powell of the Max Planck Institute for Astrophysics in Germany says, “We expected to find at least one dark object, and our results are consistent with the cold dark matter theory that explains how galaxies form, and the question now is: Will we find more? And will their numbers match theoretical models?”.

“Cold dark matter” is one of the most important theories that explain how galaxies formed and the universe was built as we see it today, and revolves around the fact that the universe in its early days was full of invisible particles that do not emit light or radiation, but have a very large mass, which is cold dark matter.

This material was moving very slowly compared to the speed of light, meaning it is not “fast or hot” as in some other theories, and because of its slowness and weight, dark matter attracts ordinary matter such as gases and dust by gravity, to gradually gather and form the major structures in the universe such as galaxies and galaxy clusters.

Powell believes that their results are consistent with the cold dark matter theory, as the discovery of the small dark object supports the idea that dark matter can clump together in small clusters as predicted by this theory, and this reinforces the belief that dark matter is indeed the “hidden building block” that built galaxies since the dawn of the universe.