Supermassive Black Holes Dance of Death

Astronomers Spot Two Supermassive Black Holes on a Collision Course
The black holes are closer to Earth, and to each other, than any other known supermassive black hole pair.

By Isaac Schultz

Through a standard telescope, the nearby galaxy NGC 7727 looks like a gossamer tumbleweed drifting in the night sky. But within it are two supermassive black holes beginning a dance that will end with their violent merger. As a team of astronomers recently found, these objects are closer to Earth than any other supermassive pair.

One of the black holes is 6.3 million times the mass of the Sun, while the other is a whopping 154 million solar masses. The duo is located 89 million light-years from Earth in the constellation Aquarius. The team determined the objects’ masses by studying how their gravitational pulls affected stars in their vicinity.

Supermassive black holes lurk at the center of galaxies—our own galaxy hosts Sagittarius A*, a roughly 4 million solar mass black hole 26,000 light-years from Earth. When two galaxies merge, the black holes end up circling one another and eventually merging themselves. These black hole mergers are some of the most violent astrophysical phenomena in the universe, and they generate the gravitational waves famously predicted by Einstein and first observed by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015.

The nearness of the NGC 7727 pair blew the previous record-holding pair out of the interstellar water—that pair was 470 million light-years from us. The team’s research is set to publish in Astronomy & Astrophysics.

“Once the black holes get much closer to each other, they will become gravitationally bound and orbit each other,” said lead study author Karina Voggel in an email to Gizmodo. “This is in theory observable, but this stage in black hole evolution lasts only a short time over a cosmic timescale, and so far we have not observed it.” Voggel, an astronomer at the University of Strasbourg in France, said that unknown galaxy merger relics like it could increase the total number of supermassive black holes by up to 30%.

“Currently, LIGO can detect gravitational wave events from black holes that merge that have a couple times the mass of our Sun,” Voggel added. “When the LISA space mission will come online in a few years, we will be able to also detect the gravitational wave events from the merging of such supermassive black holes.”

While the galaxy is visible through a normal telescope, when seen through the European Southern Observatory’s Very Large Telescope one can make out little orbs of light within the galaxy that mark where the black holes are. (The gravitational pull of black holes is so strong that light famously cannot escape from them, but the objects are often surrounded by superheated plasma that glows brightly.)

“The small separation and velocity of the two black holes indicate that they will merge into one monster black hole,” said study author Holger Baumgardt, an astrophysicist at the University of Queensland, Australia, in an ESO release.

Iron Maiden

Dance Of Death

Let me tell you a story to chill the bones
About a thing that I saw
One night wandering in the Everglades
I’d one drink but no more
I was rambling, enjoying the bright moonlight
Gazing up at the stars
Not aware of a presence so near to me
Watching my every move

Feeling scared and I fell to my knees
As something rushed me from the trees
Took me to an unholy place
And that is where I fell from grace
Then they summoned me over to join in with them
To the dance of the dead
Into the circle of fire I followed them
Into the middle I was led

As if time had stopped still I was numb with fear
But still I wanted to go
And the blaze of the fire did no hurt upon me
As I walked onto the coals
And I felt I was in a trance
And my spirit was lifted from me
And if only someone had the chance
To witness what happened to me

And I danced, and I pranced, and I sang with them
All had death in their eyes
Lifeless figures – they were undead – all of them
They had ascended from hell

As I danced with the dead
My free spirit was laughing and howling down at me
Below my undead body
Just danced the circle of dead
Until the time came to reunite us both
My spirit came back down to me
I didn’t know if I was alive or dead
As the others all joined in with me

By luck then a skirmish started
And took the attention away from me
When they took their gaze from me
Was the moment that I fled
I ran like hell, faster than the wind
But behind I did not glance
One thing that I did not dare
Was to look just straight ahead

When you know that your time has come around
You know you’ll be prepared for it
Say your last goodbyes to everyone
Have a drink and say a prayer for it

When you’re lying in your sleep, when you’re lying in your bed
And you wake from your dreams to go dancing with the dead
When you’re lying in your sleep, when you’re lying in your bed
And you wake from your dreams to go dancing with the dead

To this day I guess I’ll never know
Just why they let me go
But I’ll never go dancing no more
‘Til I dance with the dead

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