A ‘Goldilocks’ black hole about 55,000 times the mass of the Sun has been discovered by astronomers who say it is’ neither too big nor too small.
The star phenomenon, discovered by astronomers at the University of Melbourne, was found about three billion light-years away thanks to a technique that detects light from a gamma-ray burst on its way to Earth.
Astronomers say that the size of the “intermediate black hole” lies between a small “supernova” black hole and a supermassive black hole in the heart of a galaxy.
It could be an “ ancient relic ” dating back to the early universe before the first stars and galaxies formed, suggests study co-author Professor Eric Thrane of Monash University.
These ‘intermediate black holes’ may have been the seeds that, over time, gave rise to the supermassive black holes that live at the heart of every known galaxy today.
Although it is three billion light years away, researchers estimate that there are about 46,000 medium black holes near the Milky Way.
The new black hole was found by detecting a gamma-ray burst with a gravitational lens
WHAT ARE GAMMA RAY BURSTS?
Gamma-ray bursts (GRBs), energetic jets of gamma rays emanating from black holes, can be created in two different ways – resulting in long or short GRBs.
They arose from some of the most violent deaths in the universe.
Long GRBs last about a minute and scientists believe they are produced by supernova: when the core of a massive star collapses and becomes a black hole.
Short GRBs last a second and are produced when two neutron stars collide.
The discovery, through gravitational lenses, of this new long-predicted black hole type fills a “missing link” in our understanding of the universe, the team explained.
It is also called the ‘Goldilocks’ black hole because it is right in the middle of all known black hole types, neither too big nor too small.
A typical black hole, created by the explosion of a massive star at the end of its life, will be up to 10 times the mass of the sun.
In contrast, a supermassive black hole in the center of a galaxy, including the one recently photographed in M87, can be billions times as massive as the Sun.
The new type of ‘Goldilocks’ black hole is about 55,000 times the mass of our own star, filling a hole that has left astronomers baffled for years.
Lead author and PhD student at the University of Melbourne, James Paynter, said the latest discovery sheds new light on how supermassive black holes form.
“While we know that these supermassive black holes lurk in the cores of most, if not all, galaxies, we don’t understand how these colossi could get so big in the age of the Universe,” he said.
Astronomers say the size of the ‘intermediate black hole’ lies between a small ‘supernova’ black hole and a supermassive black hole at the heart of a galaxy
The new black hole was found by detecting a gravity-driven gamma-ray burst, a half-second flash of high-energy light.
This light was emitted from a pair of merging stars, and was observed to have a telltale “echo” caused by the intermediate medium black hole.
The black hole bends the path of the light from the gamma-ray burst towards Earth, so that astronomers see the same flash twice.
Powerful software developed to detect black holes from gravitational waves has been modified to determine that the two flashes are images of the same object.
The Event Horizon Telescope (EHT) collaboration, which produced the very first image of a black hole in 2019, today takes a new look at the massive object at the center of the Messier 87 (M87) galaxy: what it looks like in polarized light
INTERMEDIATE MASS OF BLACK HOLES: THE MISSING LINK IN THE EVOLUTION OF THE UNIVERSE
Medium-sized black holes are the “missing link” in the evolution of the universe.
They are between the holes created by an exploding star and supermassive black holes in the heart of a galaxy.
One recently detected using gravitational lenses was 55,000 times more massive than the sun.
They are thought to be the ‘seeds’ that led to supermassive black holes.
Researchers estimate that there are about 46,000 medium black holes in the vicinity of the Milky Way.
They are thought to be at the heart of globular clusters, collections of stars in a galaxy bound by gravity.
“This newly discovered black hole could be an ancient relic – a primordial black hole – that originated in the early Universe before the first stars and galaxies formed,” said Thrane.
“These early black holes may be the seeds of the supermassive black holes that live in the hearts of galaxies today.”
Co-author of the paper, pioneer of gravitational lenses, Professor Rachel Webster of the University of Melbourne, said the findings have the potential to help scientists take even greater strides in understanding the evolution of the universe.
“Using this new candidate for a black hole, we can estimate the total number of these objects in the universe,” explains Webster.
“We predicted that this could be possible thirty years ago, and it’s exciting to have discovered a strong example.”
The researchers estimate that there are about 46,000 medium black holes in the vicinity of our Milky Way Galaxy.
These groupings of medium black holes have long been thought to be located in the cores of globular clusters.
A globular cluster is a globular collection of stars closely related to gravity found in disk and spiral galaxies.
There are 150 known in the Milky Way and there will be many more to be found.
Galaxy M87, up to 1,000 times older than the Milky Way, is said to have as many as 13,000 globular clusters.
details of the discovery have been published in the journal Nature astronomy
BLACK HOLES HAVE GRAVITY SO STRONG EVEN LIGHT CAN’T ESCAPE
Black holes are so dense and their gravity is so strong that no radiation of any kind can escape them – not even light.
They act as intense gravitational sources that suck up dust and gas around them. Their intense gravity is believed to be what stars in galaxies revolve around them.
How they are formed is still poorly understood. Astronomers think they can form when a large gas cloud 100,000 times bigger than the sun collapses into a black hole.
Many of these black hole seeds then fuse to form much larger supermassive black holes found at the center of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the mass of the Sun, which eventually forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go “supernova”, a massive explosion that expels matter from the outermost layers of the star into deep space.