An unusual outburst about 1 billion light-years away
right here, has rocked scientists’ understanding
of the universe’s most powerful events.
Some of these are the source of the heavy elements in the cosmos,
like gold. For decades,
scientists have divided these explosions, called gamma-ray bursts,
into two groups – long and short GRBs.
Long bursts produce a flare of gamma-rays
the highest-energy form of light, that last
two or more seconds. They’re thought to be caused
by black holes forming at the center of massive collapsing
stars and are followed by supernova explosions.
Short bursts, on the other hand, last less than two seconds,
are likely caused by neutron star mergers, and are followed by
flares of visible and infrared light called kilonovae.
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But a recent event has scientists rethinking these categories.
On Dec 11, 2021, NASA’s
Swift and Fermi telescopes observed a 50-second-long
gamma-ray burst followed by the clear signs
of a kilonova. It’s called GRB 211211A.
It was later studied by the Hubble Space Telescope
along with a number of other observatories.
Scientists don’t yet know how a burst caused by a neutron star
merger could produce gamma rays for so long.
Maybe instead of two neutron stars,
one of the objects was a black hole.
Kilonovae are a known source of heavy elements like iodine,
which was essential for the development of life on Earth.
But scientists thought they were only associated with short bursts.
GRB 211211A shows,
for the first time, that kilonovae can accompany both
short and long bursts.
After 50 years of studying these events, scientists are still learning
new things about their effects on the cosmos.