The Cosmic Horseshoe\u2019s enormous size visibly warps spacetime, bending the light from nearby galaxies into a horseshoe-shaped glare called an Einstein Ring<\/a>. This fortuitous celestial quirk, along with more traditional detection methods, allowed astronomers to spot the new black hole, which has yet to be named.<\/p>\n \u201cThis is amongst the top 10 most massive black holes ever discovered, and quite possibly the most massive,\u201d Thomas Collett, study co-author and a cosmologist at the University of Portsmouth in England, said in the statement. \u201cMost of the other black hole mass measurements are indirect and have quite large uncertainties, so we really don\u2019t know for sure which is biggest.\u201d\u00a0<\/p>\n Most large galaxies appear to host supermassive black holes at their core, including the Milky Way. Cosmological models predicted that bigger galaxies, like the Cosmic Horseshoe, might be capable of hosting even larger, \u201cultramassive\u201d black holes. However, such ultramassive black holes were difficult to spot, as the conventional method of tracking the motion of stars around them\u2014stellar kinematics\u2014wasn\u2019t effective for dormant, faraway black holes.\u00a0<\/p>\n The researchers overcame this limitation with gravitational lensing, a method that doesn\u2019t depend on necessarily \u201cseeing\u201d the motion of cosmic entities. They also took observational data from the Very Large Telescope<\/a> and the Hubble Space Telescope<\/a> to create a comprehensive model of the galaxy. This two-pronged approach allowed the team to spot a \u201cdormant\u201d black hole \u201cpurely on its immense gravitational pull and the effect it has on its surroundings,\u201d explained Carlos Melo, study lead author and PhD student at the Universidade Federal do Rio Grande do Sul in Brazil, in the same statement.<\/p>\n \u201cWe detected the effect of the black hole in two ways,\u201d Collett said. \u201cIt is altering the path that light takes as it travels past the black hole, and it is causing the stars in the inner regions of its host galaxy to move extremely quickly. By combining these two measurements, we can be completely confident that the black hole is real.\u201d<\/p>\n \u201cWhat is particularly exciting is that this method allows us to detect and measure the mass of these hidden ultramassive black holes across the universe,\u201d Melos added, \u201ceven when they are completely silent.\u201d<\/p>\n Another notable aspect of the Cosmic Horseshoe\u2019s environment is that it\u2019s a \u201cfossil group.\u201d These dark, massive systems are primarily driven by gravitational forces and usually come as the final product of a series of galaxy mergers.<\/p>\n \u201cIt is likely that all of the supermassive black holes that were originally in the companion galaxies have also now merged to form the ultramassive black hole that we have detected,\u201d said Collett. \u201cSo we\u2019re seeing the end state of galaxy formation and the end state of black hole formation.\u201d<\/p>\n![\"Cosmic](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/08\/cosmic-horseshoe-black-hole-gravitational-lensing-1280x1280.png\")
Another image of the Cosmic Horseshoe, but with the pair of images of a second background source highlighted. The faint central image forms close to the black hole, which is what made the new discovery possible. Credit: NASA\/ESA\/Tian Li (University of Portsmouth) <\/p>\n