Astronomers have been monitoring the largest black holes observed in space thus far.

Through a combination of two distinct measurement techniques, researchers have recently identified that these colossal black holes possess nearly 10,000 times the mass of the ultra-massive black holes at the center of our galaxy.

This colossal black hole is situated five billion light-years from Earth, at the core of the Cosmic Horseshoe, one of the largest known galaxies. This massive galaxy seems to gather all the galaxies in its vicinity, meaning both it and its black hole have reached their ultimate sizes.

The black hole itself weighs an astonishing 36 billion times the mass of our sun.

The discovery is particularly remarkable given that these black holes are inactive, lacking the typical surrounding luminous dusty disc.

Instead, a recent study published in the Monthly Notices of the Royal Astronomical Society utilized a combination of two established methods to ascertain the size of this mega black hole.

“The ‘golden’ method generally depends on the kinematics of stars, meaning we measure how the stars move within the galaxy,” noted Carlos Mello in an interview with BBC Science Focus. He is a PhD student at a federal university in Brazil that led the research.

The speed of stars situated at the center of a galaxy correlates closely with the mass of its supermassive black hole. Scientists report that these stars are moving at astonishing velocities, around 400 kilometers (249 miles) per second, indicating an extraordinarily large black hole.

“However, this technique is most efficient for nearby galaxies where telescopes can better resolve the area surrounding the black hole,” Mello explained.

Given that the Cosmic Horseshoe is five billion light-years away, astronomers also employed a second method that utilizes the gravitational lensing effect of galaxies.

Gravitational lenses occur when light from a distant galaxy passes by a massive “lens” object, in this case, the black hole within the Cosmic Horseshoe. The gravity from this “lens” distorts the incoming light much like a magnifying glass, amplifying the light from the background galaxy while altering its appearance.

Astronomers can utilize this distortion to gauge the mass of the lensing object.

“The Cosmic Horseshoe is exceptional because it enables us to leverage both of these powerful methods simultaneously. This gives me greater confidence in the measurements of the black hole and its mass,” Mello remarked.

Both the galaxy and its black hole have achieved immense scales by merging with neighboring galaxies. This is the typical growth process for galaxies over time; ultimately, no surrounding galaxies can merge without reaching significant mass increases.

The Cosmic Horseshoe has reached this advanced stage, existing within a bubble of relatively few bright galaxies nearby.

“This discovery provides a unique insight into the culmination of galaxy and black hole formation,” Mello stated. “By examining this system, we can enhance our understanding of how other galaxies and their ultra-massive black holes evolve over cosmic time.”

About Our Experts

Carlos Mello is a doctoral student at a Federal University in Brazil.

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