Last year, a strong gamma-ray burst hit Earth, and scientists learned it was the strongest. In addition to that, it was reportedly so powerful that it affected our planet's ionospheric conductivity.
GRB 221009A Brightest Gamma-Ray Burst
GRB 221009A broke records when it flared in October 2022, 2.4 billion light years away from Earth. It was bright when discovered on Oct. 9, 2022, and given the official designation "Brightest Of All Time" (BOAT). Following a highly bright burst of high-energy gamma rays, a dim afterglow followed before it faded in a range of light wavelengths.
A new study confirmed that the incident was so powerful that it affected the electric field of Earth's ionosphere. According to astrophysicist Mirko Piersanti of the University of L'Aquila and the National Institute of Astrophysics in Italy and lead author of the study, the strong gamma-ray burst altered the ionospheric electric field at about 500 kilometers (310).
"Using both satellite observations and a new ad hoc developed analytical model, we prove that the GRB 221009A deeply impacted on the Earth's ionospheric conductivity, causing a strong perturbation not only in the bottom-side ionosphere, but also in the top-side ionosphere (at around 500 kilometers)," he explained.
The ionosphere, which lies between 50 and 1000 kilometers (or 30 and 600 miles) above Earth's surface and overlaps multiple other atmospheric layers, is a relatively thick layer of the atmosphere. It gets its name from the region of the atmosphere where the Sun's intense X and UV radiation ionizes the atoms and molecules, releasing many free electrons.
The ionosphere reflects the radio waves that humans utilize for navigation and communication. We can track the alterations in the lower ionosphere caused by strong events, such as solar flares, by observing the variations in how extremely low-frequency radio waves reflect off of it.
This is how alterations to the lower ionosphere, at altitudes of 60 to 100 kilometers, were observed by astronomers almost immediately following the identification of GRB 221009A back in October 2022. According to them, it was so strong that its effects were comparable to a solar flare.
What Is A Gamma-Ray Burst?
Gamma-ray bursts (GRBs) refer to the biggest and brightest explosions in the cosmos. They are thought to be produced during the formation of black holes billions of light years away in space.
Gamma-ray bursts can release as much energy in a few seconds as the sun can in a billion years. GRBs were once believed to be the most ferocious, violent, and potent explosions in the universe, even before BOAT was discovered.
Co-author Hendrik Van Eerten, a physicist at the Department of Physics at the University of Bath, claims that the structure of the GRB was unusual, with observations progressively exposing a narrow jet buried in the broader gas outflow where an isolated jet would often be expected.
Consequently, the jet of GRB 221009A appears to feature broad and thin "wings" that distinguish it from the jets of previous GRBs. This could help explain why astronomers could still view the BOAT's afterglow at different wavelengths months after it was first discovered.
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