Sunday, October 17

A diffuse gamma ray glow illuminates the heart of the Milky Way

A diffuse gamma ray glow illuminates the heart of the Milky Way

A diffuse gamma ray glow illuminates the heart of the Milky Way

From the disk of the Milky Way, the region of our galaxy where the largest number of stars and planets accumulate, gamma rays are emerging with a power that far exceeds anything that could be built or imagined on Earth.

It has been discovered by an investigation by the Tibet AS-gamma experiment, a cosmic ray observatory located in Yangbajing, China, at 4,300 meters above sea level.

Chinese and Japanese scientists operating such an observatory have in the past produced significant results in gamma astronomy, cosmic rays, solar physics, and particle physics. Now they have once again astonished the world.

Unexpected energy

Unexpected energy In an article that has been approved for publication in the journal Physical Review Letters, explain that the gamma rays detected by this observatory have an energy greater than that of petaelectronvolt or PeV.

If we compare this energy with that which the LHC at CERN in Geneva is capable of generating, we see that this hadron accelerator has reached 14 teraelectronvolts (TeV) of power. One PeV equals one thousand TeV.

According informs In this regard ScienceNews, these gamma rays confirm the presence of powerful cosmic particle accelerators in the center of the Milky Way.

Researchers believe that these particle accelerators create powerful cosmic rays, the mysterious particles that sweep across the galaxy and constantly bombard our planet.

Speed ​​of light

Speed ​​of light These cosmic rays travel at a speed close to the speed of light and have hundreds of times more energy than the particles produced in the most powerful accelerator ever created on our planet.

Most of the particles that make up cosmic rays are protons or nuclei of atoms, and when they collide with cosmic debris scattered throughout the galaxy, they can produce gamma rays.

Gamma rays, a type of electromagnetic radiation made up of photons, are generated in violent astrophysical phenomena: they cause outbreaks of gamma rays (GRB), the most luminous electromagnetic events that occur in the universe.


Verification Astronomers have always suspected that some regions of the galaxy we live in can accelerate cosmic ray particles to more than one PeV.

However, until now it had not been possible to confirm this power of gamma rays, nor the existence of any cosmic accelerator capable of reaching it.

The new research has proven both extremes: those accelerators exist and they generate gamma rays with energies ranging between 100 TeV and 1 PeV in the galactic disk, as they explain in their article.

The authors of the research also point out that these powerful gamma rays originate from cosmic rays that wander erratically through the galaxy, as a result of the interaction of protons with the interstellar medium.

Magnetic fields

Magnetic fields They therefore consider that cosmic rays are accelerated beyond the PeV energies in our galaxy and that they spread through the galactic disk, modulated by its magnetic fields.

This means that our galaxy is full of cosmic rays that are much more powerful than previously thought, and that they have been revealed by checking the energy of the gamma rays they generate.

The higher the energy of the gamma rays, the higher the energy of the cosmic rays from which they come, the scientists say.

This finding confirms that powerful PeV rays not only originate, but also propagate across the galactic disk, producing a diffuse glow of extreme-energy gamma rays that a Tibetan observatory has finally detected and measured.


Reference Detection of diffuse gamma-rays from the galactic disk: Evidence for ubiquitous galactic cosmic rays beyond PeV energies.  Phys. Rev. Lett. M. Amenomori et al.Accepted 21 January 2021

Image: An artist’s illustration of a bright gamma-ray burst in a star-forming region. Credit: NASA / Swift / Mary Pat Hrybyk-Keith and John Jones.

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