Cosmic rays sent to Earth are not coming from where we thought, scientists say


The cosmic rays that bombard Earth don’t come from where we think, scientists say, and we could have found their source.

For decades, researchers have thought that cosmic rays reaching Earth from the edges of the galaxy start in stars that become supernovae. That happens when they grow so large that they cannot support their own nuclei and explode.

Researchers can be sure those cosmic rays are reaching us, and at such high speeds, thanks to experiments including the High-Altitude Water Cherenkov (HAWC) observatory near Puebla, Mexico, which uses large metal water tanks that light up. when hit by high-energy particles.

But scientists now say that those high-energy particles do not appear to come from supernovae, as they are not powerful enough to do so with the large amounts of energy that have been observed. Although supernovae can destroy an entire solar system, they don’t have the power to hit us with such energetic rays, the researchers say.

Instead, the fast cosmic rays in fact appear to come from star clusters that serve as accelerators and launch the particles through the galaxy with such intense amounts of energy, according to new research.

Articles describing the new findings, which the researchers describe as a paradigm shift, have been published in Nature astronomy Y Astrophysical journal letters.

While those rays have been assumed to come from supernova remnants, the researchers say it is theoretically difficult to explain, and there has been no evidence that highly energetic cosmic rays come from such a supernova.

Researchers had already seen hints that star clusters could be responsible. But now they have seen confirmation that they can, in work that looked at the Cygnus Cocoon, a “super bubble” that surrounds an area where massive stars are forming.

Such star-forming regions appear to be prime candidates for “PeVatrons,” say the researchers. (PeVatrons is the name for PeV accelerators, where petaelectronvolts or PeVs are a marker of the amount of energy needed to move particles at such high speeds.)

“There have been several other indications that star clusters could be part of the story,” Henrike Fleischhack, one of the study researchers, said in a statement. “We are now receiving confirmation that they are capable of reaching the highest energies.”

Star clusters are made up of the remains of a supernova. They are also known as stellar cradles and are formed by winds and debris clouds that accumulate in violent and extreme areas of space.

As their name suggests, they are filled with hundreds of stars grouped together in a very limited number of space: hundreds of massive objects known as spectral type O and type B are found clustered in areas just over 100 light-years across.

It is between these stars that cosmic rays pass through the universe.

“O-type spectral stars are the most massive,” said Binita Hona, another of many researchers on the new papers. “When their winds interact with each other, shock waves are formed, which is where acceleration occurs.”

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