- 3996 - SUPERNOVA - they keep getting bigger? Astronomers have found a blast lasting for three years and is over ten times as powerful as the brightest supernova . What is it?
-------------- 3996 - SUPERNOVA - they keep getting bigger?
- The
explosive event,”AT2021lwx” was observed to be ten times brighter than any
known supernova, the explosions that occur as massive stars die. Most supernova
explosions only last a few months, this explosive event has been raging for at
least three years.
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- It is also
three times brighter than the light that is emitted as stars are ripped apart
and devoured by supermassive black holes, occurrences called "tidal
disruption events" or "TDEs."
-
- The blast
is around 8 billion light-years from Earth and it occurred when the universe
was just 6 billion years old. It was
first spotted in 2020 and was then picked up by the Asteroid Terrestrial-impact
Last Alert System (ATLAS) based in Hawaii.
-
- This change
in brightness can indicate a supernova or a gamma-ray burst (GRB) deep in the
universe or something much closer to home like a comet or an asteroid.
-
- Most
supernovae and TDEs only last for a couple of months before fading away. For
something to be bright for two plus years was immediately very unusual. This
may be the result of a black hole violently disrupting a cloud of gas with a
mass thousands of times greater than the sun. As it did so, the black hole
swallowed fragments of the gas cloud, sending shockwaves into both what remains
of the gas and into a wider donut-shaped torus of dust surrounding it, causing
them to emit bright electromagnetic radiation.
-
- While
AT2021lwx isn't actually as bright as the gamma-ray burst “GRB 221009A” spotted
by astronomers in 2022, this event that erupted from 2.4 billion light-years
away lasted for just ten hours after detection. Even though that is quite long
for a GRB, it means that AT2021lwx has put out far more energy over its entire
lifetime than this gamma-ray burst did in its own.
-
- Astronomers
took the spectrum of light that was emitted from the event and split it down
into its constituent wavelengths, measuring how light was emitted and absorbed
around the event. This allowed the researchers to calculate the distance to the
source of AT2021lwx.
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- Once you
know the distance to the object and how bright it appears to us, you can
calculate the brightness of the object at its source. The only thing in the known universe that is
as bright as AT2021lwx are supermassive black holes. When these black holes
feed on stellar gases that fall into them at high velocities, they can let off
incredibly bright emissions known as quasars.
-
- Astronomers
currently favor the explanation that sees an extremely large cloud of mostly
gaseous hydrogen or dust that was knocked from its orbit around the black hole
and sucked into it. This will only be conclusively determined when the team has
collected more data about AT2021lwx.
-
- The team
will now look at the explosion in different wavelengths of light including
X-rays. Doing so could reveal the temperature of the event and what processes
are driving it. They will also conduct computer simulations to discover if
their model of a titanic gas cloud disrupted by a black hole could account for
it.
-
May 12, 2023
SUPERNOVA - they keep getting bigger? 3996
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--------------------- --- Friday, May 12, 2023
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