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Check out this Hubble image of a
galaxy 8 billion light-years

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away. Notice anything unusual
about it? This super bright spot

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is not a star in the foreground
blocking our view, but is

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actually a quasar named 3C186
that’s inside the pictured

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galaxy. A quasar is the
extremely bright light that’s

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emitted by hot gas surrounding a
supermassive black hole. A

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supermassive black hole is a
type of black hole that’s at

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least 100-thousand times more
massive than our Sun and is at

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the center of almost every
massive galaxy. But the center

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of this galaxy is over here, in
this green circle. This galaxy’s

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quasar, and therefore its
supermassive black hole, for

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some reason is more than 35,000
light-years away from the

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galaxy’s center, and the
redshift, a spectral signature

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of the gas in the quasar, shows
that the black hole is flying

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away from the center at over
1,300 miles per second. [over

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2,000 km/s] For reference, our
Sun is moving through our galaxy

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at about 15 miles per second.
[24 km/s] This particular black

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hole is over one billion times
more massive than our Sun - what

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could have possibly moved
something so enormous? A team of

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astronomers led by Marco
Chiaberge at the Space Telescope

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Science Institute think they’ve
found the most plausible

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explanation. Taking a look at
the Hubble image, there is some

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faint material surrounding the
galaxy called tidal tails, and

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these are produced by a
gravitational tug between two or

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more colliding galaxies. If this
galaxy is actually two galaxies

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that merged, then it’s possible
their two central supermassive

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black holes also merged. As
enormous objects like

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supermassive black holes are
merging, they create ripples in

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the fabric of spacetime called
gravitational waves. The two

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black holes whirl around each
other, getting closer and

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closer, and fling out
gravitational waves like water

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from a lawn sprinkler. If the
two black holes are a bit uneven

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- maybe one’s more massive,
maybe one’s rotating a little

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faster - then they fling out
these gravitational waves more

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strongly along one direction.
Once the two black holes finally

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collide, the newly merged black
hole shoots off in the opposite

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direction from the strongest
gravitational waves. And that’s

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what astronomers think happened
to this supermassive black hole.

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Based on its enormous mass and
velocity, the energy needed to

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jettison this black hole was
equivalent to something like 100

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million supernovas exploding
simultaneously. So while this

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may not go on your list of the
top prettiest Hubble images,

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just think - you’re looking at
the light emitted 8 billion

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years ago from gas orbiting a
1-billion-solar mass black hole

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that is flying through its
galaxy because it was shot off

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like a rocket from the
gravitational waves produced by

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the merging of two supermassive
black holes - and if that’s not

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cool, I don’t know what is.

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nasa.gov/hubble @NASA_Hubble