Cosmic rays are high-energy particles accelerated to excessive velocities approaching the pace of sunshine. It takes a particularly highly effective occasion to ship these bits of matter blazing via the Universe. Astronomers theorize that cosmic rays are ejected by supernova explosions that mark the dying of supergiant stars. However latest information collected by the Fermi Gamma-ray area telescope casts doubt on this manufacturing technique for cosmic rays, and has astronomers digging for a proof.
It’s not straightforward to inform the place a cosmic ray comes from. Most cosmic rays are hydrogen nuclei, others are protons, or free-flying electrons. These are charged particles, which means that each time they arrive throughout different matter within the Universe with a magnetic subject, they alter course, inflicting them to zig-zag via area.
The route a cosmic ray comes from when it hits Earth, then, shouldn’t be seemingly the route it began in.
However there are methods to not directly observe down their origin. One of many extra promising strategies is by observing gamma rays (which do journey in straight traces, fortunately).
When cosmic rays stumble upon different bits of matter, they produce gamma rays. So when a supernova goes off and sends cosmic rays out into the Universe, it must also ship a gamma-ray sign letting us understand it’s occurring.
That’s the idea, anyway.
However the proof hasn’t matched expectations. Research of outdated, distant supernovas present some gamma ray manufacturing occurring, however not as a lot as predicted. Astronomers defined away the lacking radiation because of the supernovas’ age and distance. However in 2023, the Fermi telescope captured a shiny new supernova occurring close by. Named SN 2023ixf, the supernova went off simply 22 million light-years away in a galaxy known as Messier 101 (higher generally known as the ‘Pinwheel Galaxy’). And but once more, gamma rays have been conspicuously absent.
“Astrophysicists beforehand estimated that supernovae convert about 10% of their complete vitality into cosmic ray acceleration,” said Guillem Martí-Devesa, College of Trieste. “However we now have by no means noticed this course of straight. With the brand new observations of SN 2023ixf, our calculations end in an vitality conversion as little as 1% inside a number of days after the explosion. This doesn’t rule out supernovae as cosmic ray factories, but it surely does imply we now have extra to find out about their manufacturing.”
So the place is all of the lacking gamma radiation?
It’s doable that interstellar materials across the exploding star might have blocked gamma rays from reaching the Fermi telescope. However it may additionally imply that astronomers have to search for various explanations for the manufacturing of cosmic rays.
No person likes an excellent thriller higher than astronomers, and digging into the lacking gamma radiation might ultimately inform us an entire lot extra about cosmic rays and the place they arrive from.
Astronomers plan to review SN 2023ixf in different wavelengths to enhance their fashions of the occasion, and can after all maintain an eye fixed out for the subsequent large supernova, in an effort to grasp what’s going on.
The latest gamma-ray information from SN 2023ixf will likely be revealed in Astronomy and Astrophysics in a paper led by Martí-Devesa.
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