The amazing gamma-ray burst, called GRB 221009A, continues to amaze even though it has been more than a year since it was seen. Scientists from Italy have recently published a study that shows how the ionosphere of our planet is affected due to its high intensity and long wavelength.
The ionosphere is one of the Earth’s atmospheric layers, stretching from 60 km to more than 950 km in height. Containing an energetic plasma, its lower half, called the lower part, extends up to 350 km. Beyond 350 km is the upper half, called the mountain side.
Charging to the top-side
According to Mirko Piersanti, who is a professor at the University of L’Aquila, the effects of gamma-ray bursts have often been observed in the lower part but rarely in the upper part of the ionosphere. “That’s because the plasma density and adhesion in the upper side is much lower than the lower side. Also, to observe this effect, you need a satellite that can make observations, orbit at this level,” said Piersanti.
One such satellite happens to orbit the Earth at an altitude of 507 km. “The China Seismo Electromagnetic Satellite (CSES), which is a Chinese-Italian mission, was in the right place at the right time, under the electromagnetic region of this gamma-ray burst. “The satellite has an instrument that recorded a significant spike in the electric field in the upper ionosphere,” Piersanti said.
The link between this observation and the gamma-ray burst event was not clear at first. According to Piersanti, typically the ionosphere dynamics are completely driven by the Sun. “The first thing we thought was probably something coming from the West. But the Sun emits lights that do not correspond in time to what we observe. Also, at that time, we were sure that the gamma-ray burst would not be able to make such a difference in the upper ionosphere.”
“However, after analyzing the data from CSES as well as ESA’s Integral space telescope, we changed our mind. Now, we think it’s possible that gamma-ray bursts can play a role in the entire ionosphere,” he said.
Saved by distance
While the sequence of events that created GRB 221009A (supernova explosion or black hole creation) is not determined, the gamma-ray source is almost 2 billion light-years away from our Milky Way galaxy.
According to Piersanti, if such a distant event could cause a large disturbance in the less sensitive part of the ionosphere, an event in our galaxy (which is 100,000 light years across) could cause damage. to the ozone layer of the Earth.
“I haven’t gone through the ozone layer data, but this gamma-ray burst has the potential to disrupt the ozone layer. In fact, with the help of statistical analysis, we work on the possible effects of gamma-ray bursts like GRB 221009A can cause in the ozone layer. We are also creating a table of past gamma-ray bursts and observations of the ozone layer and trying to see if they match,” he said.
Nature Communications, 2023. DOI: 10.1038/s41467-023-42551-5
Dhananjay Khadilkar is a journalist based in Paris.