A decade ago, a special network of telescopes in Africa detected electrons from the most powerful cosmic rays (CRe) ever recorded on Earth. They arrived in what we could call a chaotic rain and exceeded standard measurements by several orders of magnitude. Scientists do not know exactly its origin, however, they now know one thing for certain: whatever its source, it is very close to Earth.
What are cosmic rays?
In space, colossal phenomena such as supernovae, black holes or pulsars expel extremely energetic subatomic particles that travel at speeds close to light. These bursts sometimes consist of high-energy rays of light (gamma rays) and sometimes are waves of charged particles, such as electrons and their counterparts, positrons.
On Earth, scientists have developed methods to measure these shots and detect their sources millions of light years away. The HESS observatory in Namibia specializes in locating these sources through Cherenkov radiation, a blue microflash produced by charged particles passing through a medium such as water.
Over the past 10 years, the HESS observatory has detected the most energetic electrons recorded by science. This information was hidden among the research center’s data. An unprecedented effort between multiple German universities has revealed an energetic diagnosis of these particles. The sensors recorded cosmic ray electrons of up to 40 teraelectronvolts (TeV), while CRes usually record around one TeV.
In search of the source of those energetic electrons
It is not possible to detect the source of these particles because the electrons do not arrive as a cannon shot, but as scattered rain. They do not travel in a straight line because they interact with the planet’s magnetic field, distributing themselves everywhere.. It is only possible to infer that they come from a natural particle accelerator in space. However, in their energy levels there are some vague clues about the location of the phenomenon. Scientists conclude that the origin is surprisingly close to the solar system.
“This is an important result, as we can conclude that the measured CRe most likely come from very few sources close to our own solar system, up to a maximum of a few 1,000 light years awaya very small distance compared to the size of our galaxy,” Kathrin Egberts of the University of Potsdam, Germany, one of the authors of the study, explained in a statement.
There is a notable energetic slope in the readings. According to experts, this detail, together with the probable separation distance, considerably reduces the list of possible sources of these CRe. Currently, candidates include the Monogem Ring supernova remnant, the dying stars Velorum and Y2, or pulsars such as Vela or Geminga. In any case, astronomers now have a new region of interest to study the acceleration of particles naturally.
The possibility that they come from an explosion remnant of a star that has already dissipated is also not ruled out. In that case, there will be no way to know where that wave of charged electrons came from.
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