Astronomers have discovered and quantified the largest black hole ever found. This colossal black hole approaches the theoretical maximum size allowable in the universe and is approximately 10,000 times the mass of Sagittarius A*, the supermassive black hole located at the center of the Milky Way.
This Hubble image features a horseshoe-shaped gravity lens (from center to right). Behind it is a blue galaxy, distorted into a horseshoe-shaped ring by the space-time distortion caused by the massive orange galaxies in the foreground. Image credits: NASA/ESA/Hubble.
The newly identified ultramassive black hole resides in the Space Horseshoe Gravity Lens System, which is among the largest known strong gravitational lenses.
This lens system, referred to as SDSS J1148+1930 and CSWA 1, lies 5 billion light years away in the Leo constellation.
“Typically, mass measurements of black holes in such distant systems can only be done when they are active,” remarks PhD Carlos Melo from Universidade Federativa do Rio Grande do Sul.
“However, these estimates based on accretion are often fraught with significant uncertainty.”
“Our method integrates strong gravitational lenses with stellar dynamics to yield more direct and reliable measurements, even in these distant systems.”
“The black holes we discovered rank among the top 10 largest black holes known, possibly even the largest,” adds Professor Thomas Collett from the University of Portsmouth.
“Most existing mass measurements for black holes are indirect and come with high uncertainties, so I can’t definitively say which one is the largest. But our new method provides much greater confidence in the mass of this black hole.”
The research team employed a synergy of gravitational lenses and stellar motions to locate the space horseshoe-shaped black holes.
This technique is considered the gold standard for black hole mass measurement, but galaxies are often too small in the sky to resolve areas containing these supermassive black holes, limiting effectiveness in distant contexts.
“The inclusion of a gravitational lens allowed us to explore further into the cosmos,” noted Professor Collett.
“We observed the influence of a black hole in two specific ways: it alters the path light takes as it navigates through the black hole, and stars in the galaxy’s core are observed moving incredibly fast (almost 400 km/s).”
“By correlating these two measurements, we can confidently establish the black hole’s authenticity.”
“This discovery pertains to a ‘dormant’ black hole, which does not actively consume material at the time of observation,” Melo explained.
“The detection relied solely on its immense gravitational pull and its effects on surrounding matter.”
“What’s particularly thrilling is that this method enables us to identify and gauge the masses of these elusive supermassive black holes across the universe, even when they lie completely dormant.”
An intriguing aspect of the Cosmic Horseshoe system is that its host galaxy is classified as a fossil group.
Fossil groups represent the final phase of the universe’s most colossal gravitationally-bound structures, formed from the collapse of a single, large galaxy devoid of bright companions.
“It is plausible that the supermassive black holes originally found in the companion galaxy contributed to the formation of the supermassive black holes we have identified,” Professor Collett noted.
“Thus, we can observe both the conclusion of galaxy formation and the cessation of black hole growth.”
The team’s paper was published today in Monthly Notices of the Royal Astronomical Society.
____
Carlos R Melo-Carneiro et al. 2025. We are pleased to announce the discovery of a 36 billion solar-mass black hole at the core of the Cosmic Horseshoe Gravity Lens. MNRAS 541(4): 2853-2871; doi: 10.1093/mnras/staf1036
Source: www.sci.news
