This year, on April 10th, scientists were
finally able to do the unthinkable: they allowed
humanity to look straight into the abyss of
a super-massive black hole and take a photo
like a tourist attraction!
But even after these accomplishments, we still
don’t know much about black holes at all,
since one of them has challenged the whole
scientific community with new impossible feats.
In the middle of July 2019, black holes puzzled
astronomers once again.
New observations were made possible, thanks
to the famed Hubble telescope, by a team of
European scientists.
Their study showed that a relatively small
black hole, situated at the core of NGC 3147,
contradicts all our expectations by almost
completely mimicking its much bigger siblings.
To show you how exceptional this discovery
is, I’ll have to start with the most basic
question.
What is a black hole?
It’s the tiniest and heaviest object possible
in the universe.
It can swallow entire stars with ease and
is absolutely invisible to the human eye.
But wait a minute!
What was that giant, visible, orange thing
in the pictures then?
Did scientists deceive us with another computer
simulation?
No.
Not at all.
The photos are as real as it gets.
Except the image in the photos is not of a
Black Hole itself.
I shall explain.
Every black hole was once a shining star,
just like the others you see in the night
sky.
At the end of its life, a star can collapse
onto itself and condense all of its enormous
mass into a tiny dot of space.
Such an incredibly dense object will produce
a gravitational force that’ll practically
tear a hole in time-space itself and bend
the sole matter of reality around it.
From the moment of collapse, this monstrous
gravity will attract, and eagerly consume,
every piece of matter around it.
Even the lightest and fastest particles in
the universe, like photons, of which light
consists, wouldn’t be able to escape this
unstoppable force.
The core, and center of mass, of this black
hole is called a singularity.
This is the single cause of all the madness
that’s going on around it.
The mass of this thing can be from hundreds
of millions of the Sun’s mass, to hundreds
of billions!
And it takes so little space in volume, that
its density is almost infinite.
No wonder this thing seemingly breaks all
the laws of physics!
In fact, the density is the most exciting
thing about black holes.
You see, it turns out that any object can
become a tiny black hole if compressed enough.
For example, our planet would have to shrink
to a third of an inch to become a tiny singularity
of its own kind, and start to bend reality
around itself.
Of course, this can’t happen, but it happens
to exhausted stars.
The surrounding space near the singularity
is the notorious event horizon.
This is exactly why black holes are called
black, though it’s not entirely true.
Normally, you can tell that something is black
because this color doesn’t reflect light
at any of its wavelengths.
The event horizon of black holes is black
because none of the light that gets into them
can escape.
So, black holes aren’t really black, they’re
just invisible – they’re more than a tangible
manifestation of nothingness for any light-sensitive
device.
The only one of its kind in the whole universe.
The thing that makes the black hole visible,
and is depicted in the recently released photos,
lies beyond the event horizon.
It’s called the accretion disk.
It’s a brightly illuminated disk of matter,
swirling towards the center of a black hole
like when a giant drain forms a quasar.
Quasars have their place among the oldest
celestial bodies known to humanity, because
their immense brightness can outshine even
a whole bunch of stars put together.
This brightness is achievable because all
the mass that surrounds a black hole is rotating
around it at a tenth of the speed of light.
A movement this fast leads to constant outbursts
of radiation, and some of it shows itself
in the visible spectrum as light and heat.
Accretion disks consist mostly of superheated
gas and space dust, and the speed of their
movement increases the closer they get to
the event horizon.
The biggest and shiniest accretion disks are
considered to have supermassive black holes
situated in the cores of the biggest and brightest
galaxies.
And it’s easy to guess why.
The more matter a black hole must feast upon,
the bigger its mass.
Its event horizon also gets bigger, and an
accretion disk forms around it.
This is exactly the reason why the NGC 3147’s
black hole is so unique.
It isn’t supposed to have one, but it does.
Let’s compare some galaxies and black holes
in their centers to further elaborate on this
glaring difference.
The brightest example would be the black hole
in the middle of the largest galaxy known
to us in existence, and the brightest galaxy
of its cluster.
This galaxy is so large that it would be hard
to imagine it using just numbers.
If this colossus was to replace our own galaxy,
it would not only take the place of the Milky
Way, but also of several neighboring galaxies
altogether.
This giant is the IC 1101 galaxy.
When it was first discovered, it was taken
for a huge orange nebula – an aftermath
of the supernova explosion.
It took several years to get to the shocking
truth – the orange color we see is the light
of about 100 trillion stars collected in one
elliptical galaxy.
Most of them looked like ancient red dwarf
stars, giving away their tired yellow and
orange light.
But the biggest surprise was hiding in the
middle of it.
The supermassive black hole at the core of
IC 1101 suits its huge galaxy well.
This terrifying monster is heavier than about
40 billion masses of the Sun.
The accretion disk is as huge and luminous
as can be expected.
It’s much like this same black hole from
the photos.
Only black holes this huge are sometimes called
ultra-massive, giving us a rare chance to
visibly detect them.
Let’s move closer to our home for a minute.
Our galaxy is much, much smaller than IC 1101,
and not as luminous.
The Milky Way is just 100,000 light-years
across – sounds like nothing when compared
to the supposed 6 million light-years of IC
1101’s diameter.
But our galaxy is still rich enough to feed
its black holes properly.
The most notable black hole in the Milky Way
is in the Sagittarius constellation, right
in the middle of the spiral of stars that
our galaxy’s basically made of.
We’re 26,000 light-years from it, and it’s
more than 4 billion times heavier than the
Sun, which makes it a supermassive black hole.
Although Sagittarius’s black hole is shrouded
by gas clouds, blocking our view, scientists
were able to get an image based on the radio
spectrum eradiation coming from its accretion
disk.
And then we have spiral galaxy NGC 3147, 130
million light-years away from us.
This galaxy is small, and not dense enough
to constantly feed something as big and powerful
as a supermassive black hole.
Black holes in these galaxies are often called
starving black holes for a reason.
It’s expected that black holes, in a position
this unfortunate, can’t have furious swirling
accretion disks around them.
It’s far more probable that it would have
some concentrated gas around it, in a shape
more akin to a donut, and nowhere near as
luminous.
Still, against all odds, NGC 3147 has the
same kind of accretion disk as its bigger
siblings.
According to our knowledge, this is almost
impossible; and this galaxy was selected precisely
to find a black hole with no accretion disk.
But as they say, there’s no negative result
in scientific research.
Sometimes unexpected findings can teach us
a lot more than pure success.
For now, no one knows how this starving black
hole can support this disk.
To uncover the secret, Hubble stays busy searching
for other galaxies with a lesser luminosity
to find new black holes and see if they show
similar abrupt qualities.
It’ll not only allow astronomers to study
the accretion disks of starving black holes,
but will also present a unique opportunity
to test Albert Einstein’s theories of relativity.
The disk of NGC 3147’s black hole is placed
so close to the event horizon that the light
it’s emitting is twisting like nowhere else.
This is exactly what scientists had been looking
for.
There’s no better place to delve into the
fabric of laws, ruling the relations between
time and space, than a reality-bending black
hole with such rare properties.
How about you?
What secrets do you think black holes can
show us in the future?
Wormholes?
Another reality?
Let me know down in the comments!
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