The Mystery "Galactic Wall" is Keeping Cosmic Rays out of Our Galaxy's Center

By: April Carson

Astronomers assessed their findings of the gamma-range central molecular zone and determined the energy density of cosmic rays based on observed brightness. It was discovered that, on average, this density inside the cloud is significantly lower than that outside of it. Scientists consider that this may imply a physical barrier that prevents cosmic rays from entering the Milky Way's galactic center.

A mysterious barrier was discovered in the Milky Way

It is also unclear where and how cosmic rays in our galaxy are boosted to high energies (and especially to extremely high ones – about 10 15 electron volts). There are a few theoretical ideas that have yet to be verified by observation.

To learn more about how cosmic rays are accelerated, it's important to seek for areas where the distribution of cosmic rays differs from the galactic smooth quasi-stationary background. In such locales, there should be cosmic ray accelerators, which provided the area with a portion of "new" rays that had not yet combined with the established background.

As a result, from such data, more specific information on the accelerator's characteristics and cosmic ray propagation throughout the galaxy may be obtained than would be possible through conventional average background observations.

The Chinese Academy of Sciences' astronomers concentrated their efforts on the galactic center's molecular zone, a dense molecular cloud where scientists believe the accelerator (or accelerators) for high-energy cosmic rays is located. The researchers examined archival data from the Fermi gamma-ray telescope's energy range of 10 9 -10 12 electron volts and orientation that corresponds to the galaxy's center from August 4, 2008, to February 1, 2020.

How did scientists analyze the data?

The scientists divided the angular map into sections with a thickness of 0.5 degrees and determined the observed luminosities of each section in the gamma range as well as the gas mass within them, utilizing this technique to study cosmic rays inside and outside the main molecular zone. The authors took advantage of the fact that cosmic rays are produced as a result of the encounter between cosmic rays and matter to estimate the average energy density of cosmic rays (in the corresponding energy range) at each site.

The density of solar rays within the core molecular zone was found to differ significantly from that outside it. The density level inside the cloud was similar to that observed near the Sun, and up to twice less than that in remote regions at equal distances from the galaxy's center.

The researchers also observed that the larger an object's energy density, the more quickly it rotates. When considering objects in terms of behavior in space, however, the energy density at its edges was about half that of its center, but it barely varied with distance from the galactic core.

Is there a barrier in the center of the Milky Way?

According to astronomers, this might be a physical mechanism like a barrier that prevents cosmic rays from traveling into the Milky Way's core molecular zone - for example, an effective configuration of the magnetic field around the edges of a cloud.

If the researchers' guess is later verified, this cloud-isolation technology may be used to examine the design of the proposed cosmic ray accelerator complex in further depth.

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About the Blogger:

April Carson is the daughter of Billy Carson. She received her bachelor's degree in Social Sciences from Jacksonville University, where she was also on the Women's Basketball team. She now has a successful clothing company that specializes in organic baby clothes and other items. Take a look at their most popular fall fashions on

To read more of April's blogs, check out her website! She publishes new blogs on a daily basis, including the most helpful mommy advice and baby care tips! Follow on IG @bossbabymav





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