The incredible gamma-ray burst, called GRB 221009A, is still amazing even though it’s been more than a year since it was detected. Italian scientists recently published a study showing how the Earth’s ionosphere was affected as a result of its high intensity and long duration.
The ionosphere is a layer of Earth’s atmosphere that extends from 60 km to over 950 km in altitude. Its lower half, which contains electrically charged plasma, is called the base and extends up to 350 km. Beyond 350 km, there is an upper half called the topside.
Charging on top
According to Mirco Piersanti, a professor at the University of L’Aquila, gamma-ray burst effects are often observed in the lower part of the ionosphere, but rarely in the upper part. “That’s because the plasma density and conductivity on the top surface are much lower than on the bottom surface. And to observe this effect, we need observable satellites orbiting this layer,” Piasanti said.
Such a satellite happened to be orbiting the Earth at an altitude of 507 km. “The China Earthquake and Electromagnetic Satellite (CSES), a joint Chinese-Italian mission, was in the right place at the right time under the irradiation zone of this gamma-ray burst. It has equipment that records spikes,” Piasanti said.
The relationship between this observation and the gamma-ray burst phenomenon was not initially clear. Normally, the dynamics of the ionosphere are driven entirely by the sun, Piersanti said. “Our first thought was that maybe something was coming from the sun. But the sun emits flares that don’t match in time with what we observed. Also, at the time, we were confident that gamma-ray bursts could never cause such changes in the top ionosphere.”
“But after analyzing data from CSES and ESA’s Integral Space Telescope, we changed our opinion. We now believe that gamma-ray bursts can affect the entire ionosphere,” he said. said.
saved by distance
The sequence of events that led to GRB 221009A (supernova explosion or black hole creation) remains unknown, but the gamma-ray source is located almost 2 billion light-years away, a significant distance from our Milky Way galaxy .
According to Piersanti, if such distant events can cause significant disturbances in the relatively less conductive parts of the ionosphere, events occurring in our galaxy (100,000 light-years wide) It has the potential to damage the Earth’s ozone layer.
“Although we have not looked at data on the ozone layer, this gamma-ray burst could disturb the ozone layer. In fact, with the help of statistical analysis, we have determined that gamma-ray bursts like GRB 221009A can cause damage to the ozone layer. “We are studying possible effects. We are also tabulating past gamma-ray burst and ozone layer observations and trying to see if they match,” he said. .
Nature Communications, 2023. DOI: 10.1038/s41467-023-42551-5
Dhananjay Kadirkar is a journalist based in Paris.