If you thought black holes were scary, wait until you hear about ultramassive black holes. These cosmic monsters are the most massive objects in the universe, weighing between 10 billion and 40 billion times the mass of our sun. They are so huge that they can swallow entire galaxies and bend light around them.
Recently, astronomers from Durham University in the UK announced that they have discovered an ultramassive black hole about 30 billion times the mass of our sun, making it one of the biggest black holes ever found. This black hole is located in the center of a galaxy that is part of a cluster called Abell 1201, about 2.7 billion light-years away from Earth.
How did they find such a colossal beast? They used a clever trick based on Einstein’s theory of general relativity, which predicts that massive objects can warp the fabric of space-time around them. This means that a black hole can act like a giant magnifying glass, bending and amplifying the light from more distant objects behind it. This phenomenon is called gravitational lensing, and it can create distorted images of distant galaxies, such as arcs or rings.
The astronomers used images from the Hubble Space Telescope to spot a giant arc of light behind the galaxy that hosts the black hole. This arc was actually a distorted image of another galaxy that was behind the black hole from our point of view. By measuring the shape and brightness of this arc, they could estimate the mass of the black hole that caused it.
But that was not enough to confirm their discovery. They also had to use supercomputer simulations at Durham University to model how the light from the background galaxy would be affected by different masses and positions of the black hole. They compared their simulations with the Hubble data and found a good match for a black hole with a mass of about 30 billion solar masses.
This is an extremely exciting discovery, because it is the first time that gravitational lensing has been used to find an ultramassive black hole. Most of the other ultramassive black holes that we know about are detected by their radiation, which is produced when they devour matter around them. However, some ultramassive black holes may be inactive or hidden by dust and gas, making them hard to spot with conventional methods.
Gravitational lensing opens up a new window to study these elusive objects and learn more about their origins and evolution. How did they grow so large? When did they form? How do they affect their host galaxies and clusters? These are some of the questions that astronomers hope to answer with future observations and simulations.
Ultramassive black holes are rare and mysterious, but they may not be as uncommon as we think. The researchers said that their method could reveal many more ultramassive black holes beyond our local universe, and perhaps even some that are even bigger than this one. The sky is full of surprises, and we may just need a little help from Einstein to see them.