The biggest rogue in the universe: Monster black hole with the mass of a billion suns spotted being kicked out of its home galaxy


  • Hubble spotted evidence of a rogue black hole far outside of the galactic core
  • Astronomer suspect it was kicked out of center as two large black holes merged
  • Merger would have unleashed powerful gravitational waves, flinging it out 
With the energy of 100 million supernovae, gravitational waves may have ejected a supermassive black hole from the center of a distant galaxy.
The Hubble Space Telescope spotted a rogue black hole that’s said to be the largest yet to be found outside of a galactic core, weighing more than 1 billion suns.
Astronomer suspect the ‘monster object’ was kicked out of the center as two large black holes merged, unleashing powerful gravitational waves.
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The Hubble Space Telescope spotted a rogue black hole that’s said to be the largest yet to be found outside of a galactic core. Astronomer suspect the ‘monster object’ was kicked out of the center as two large black holes merged, unleashing powerful gravitational waves
The Hubble Space Telescope spotted a rogue black hole that’s said to be the largest yet to be found outside of a galactic core. Astronomer suspect the ‘monster object’ was kicked out of the center as two large black holes merged, unleashing powerful gravitational waves

HOW THEY THINK IT HAPPENED 

When the two galaxies merged, their black holes would have settled into the center of the new elliptical galaxy.
These two objects would then whirl around each other, flinging out gravitational waves, according to NASA.
Over time, the black holes would move closer to each other – and, if they do not have the same mass and rotation rate, gravitational waves would be released more strongly in one direction.
Once these two black holes collide, they both stop producing waves.
This causes the newly merged black hole to recoil in the opposite direction of the strongest waves, and shoot off like a rocket.The find, according to NASA, was out of the ordinary.
‘When I first saw this, I thought we were seeing something very peculiar,’ said team leader Marco Chiaberge of the Space Telescope Science Institute (STScI) and Johns Hopkins University.
‘When we combined observations from Hubble, the Chandra X-ray Observatory, and the Sloan Digital Sky Survey, it all pointed towards the same scenario.
‘The amount of data we collected, from X-rays to ultraviolet to near-infrared light is definitely larger than for any of the other candidate rogue black holes.’
Hubble images in visible and near-infrared light revealed a bright quasar named 3C 186 in a galaxy 8 billion light-years away.
But, the object was far from the galaxy’s core.
These are known to be energetic signatures of black holes, and are typically found in the center.
‘I was anticipating seeing a lot of merging galaxies, and I was expecting to see messy host galaxies around the quasars, but I wasn’t really expecting to see a quasar that was clearly offset from the core of a regularly shaped galaxy,’ Chiaberge said.
‘Black holes reside in the center of galaxies, so it’s unusual to see a quasar not in the center.’
The researchers investigated the phenomenon further, calculating the black hole’s distance from the core by comparing the distribution of starlight in the host galaxy with that of a normal elliptical galaxy.
And, they found that it had travelled more than 35,000 light-years from the center – further than the distance between the sun and the center of the Milky Way.
Spectroscopic observations with Hubble and the Sloan survey allowed the team to estimate the black hole’s mass, along with the speed of gas underneath.
‘To our surprise, we discovered that the gas around the black hole was flying away from the galaxy’s center at 4.7 million miles an hour,’ said Justin Ely of STScI.

WHAT ARE SUPERMASSIVE BLACK HOLES? 

Supermassive black holes are incredibly dense areas in the centre of galaxies with masses that can be billions of times that of the sun.
They act as intense sources of gravity which hoover up dust and gas around them.
Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood.
Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun's mass, that ultimately forms into a black hole after it runs out of fuel and collapses. The measurement also revealed that the black hole is moving fast enough to travel the distance from Earth to the moon in three minutes.
The discovery of faint, arc-shaped features known as ‘tidal tails’ in the Hubble image revealed gravitational tug may have played a role in the black hole’s bizarre placement.
These features are created by the gravitational tug between two colliding galaxies, and the researchers say the 3C 186 system may have merged with another, causing their two central black holes to merge.
And, when these two massive objects collided, they stopped producing gravitational waves.
This would cause the newly merged black hole to recoil in the opposite direction of the strongest gravitational waves – and, it would shoot off ‘like a rocket.’
Hubble images in visible and near-infrared light revealed a bright quasar named 3C 186 in a galaxy 8 billion light-years away. But, the object was far from the galaxy’s core
Hubble images in visible and near-infrared light revealed a bright quasar named 3C 186 in a galaxy 8 billion light-years away. But, the object was far from the galaxy’s core
‘This asymmetry depends on properties such as the mass and the relative orientation of the black holes’ rotation axes before the merger,’ said Colin Norman of STScI and John Hopkins.
‘That’s why these objects are so rare.’
The researchers say another explanation could be that the bright object does not reside within the galaxy, but is instead behind it.
But, they say this scenario is unlikely.
If their hypothesis is correct, it would be strong evidence that supermassive black holes can merge.
While others have been suspected, none have been confirmed.