"Laso" first obtains cosmic rays in the W51 region, key evidence of the acceleration limit｜Bolan Daily

" Laso " receives cosmic rays from W51 region for the first time

Key evidence for the acceleration limit

The LHAASO, a major national scientific and technological infrastructure, officially released the precise measurement of the high-energy gamma radiation in the W51 composite region, certifying it as an ultra-high-energy cosmic ray accelerating object and obtaining evidence of its highest energy limit for accelerated cosmic rays.

The W51 region is one of the largest and most active "star factories" in the Milky Way. It is also one of the few celestial regions certified to have GeV energy hadron cosmic ray acceleration. It plays an important role in solving the century-old mystery of the "origin of cosmic rays."

Using the data from the "Lasso" experiment, researchers expanded the energy spectrum measurement in this area to the ultra-high energy region for the first time, and clearly observed the "softening" structure of the gamma-ray energy spectrum at tens of TeV, which corresponds to the acceleration limit of radiation particles.

The energy spectrum measured by "Laso" is perfectly connected with the measurements of the Fermi-LAT satellite in the low-energy region. The precise energy spectrum measurement spanning 6 orders of magnitude provides evidence that the gamma radiation in the W51 region originates from the collision of cosmic rays and molecular clouds, indicating that the maximum energy limit of cosmic ray acceleration in the W51 recombination region is around 400 TeV.

The supernova remnant SNR W51C located in the W51 region is a possible source of cosmic ray acceleration, and this measurement provides evidence that SNR can accelerate cosmic rays to the ultra-high region of >100 TeV.

The relevant research results were published in Science Bulletin on July 16. The results were completed by the "Lasso" international collaboration team led by the Institute of High Energy Physics of the Chinese Academy of Sciences.

Measurement of the wide-band gamma-ray energy spectrum in the W51 region and the fitting results of the hadron interaction model to the energy spectrum data

Why is freestyle the fastest swimming style ?

Swimming is a major gold medal winner in the Olympics. Not only do they have competitions of various distances, but they are also divided into four swimming styles. The relay events are even more exciting. The swimmers' fit bodies and graceful swimming styles also make the competitions highly entertaining.

However, just like what is offside in football games and whether there is a traveling step in basketball games, swimming competitions are also full of question traps, such as questions like "Why is freestyle the fastest?"... Once you can't answer it, it's just a waste of time.

So why is freestyle the fastest? The answer is that freestyle is the swimming style with the smallest drag coefficient. The four words "drag coefficient" must be spelled out in full, and the last two words are where professionalism is reflected.

The resistance is proportional to the resistance coefficient, the square of the speed and the water retaining area. Because of the fast speed of freestyle, its resistance is not the smallest. However, Yan Weixing and others from Tsinghua University measured the dynamic resistance and resistance coefficient of freestyle and breaststroke through experiments (Figures 1 and 2, C is the resistance coefficient). The resistance coefficient of freestyle is only about 50% of that of breaststroke.

If freestyle and breaststroke move at the same speed, the resistance of freestyle will be less than that of breaststroke. From this perspective, the smaller the resistance coefficient, the less effort a swimming style will have.

Table 1 Dynamic drag coefficients of freestyle swimmers

Table 2 Dynamic drag coefficients of athletes in breaststroke

To study poisonous mushrooms,

He finished eating and went into...

Scientists have long wondered: Why do psychedelic mushrooms distort our perception of time and space?

Foreign scientists had colleagues feed him a large dose of psilocybin, a powerful hallucinogen that makes psilocybin pale in comparison. When he began to pass out, he got into an MRI machine.

His brain scans showed changes in many areas of his brain when he was taking the drug compared to when he wasn't taking the drug, but the biggest changes were in an area of ​​the brain called "synchronous services."

This area provides the most basic sense of self, space and time for human life. After taking the drug, the connection between neurons in the area of ​​the brain responsible for "synchronous service" was almost cut off, which may explain why people experience hallucinations - because the time and space in daily life now seem very strange.

From another perspective, the brain, the system for thinking about the relationship between self and the world, is temporarily completely out of sync.

Brazilian Psilocybe (Image source: Wikipedia)

Can the moon not only be used to grow vegetables but also to provide fertilizer?

Recently, in the lunar soil samples brought back by my country's Chang'e-5 mission, Chen Xiaolong's team from the Institute of Physics of the Chinese Academy of Sciences discovered a mineral crystal rich in water molecules and ammonium, ULM-1. This discovery provides new "hard evidence" for the existence of water on the moon.

If we can find water on the moon, it will greatly reduce the cost of transporting water from the earth. In addition, this water can be used for plant cultivation and agricultural production.

Planting some vegetables, grain crops, etc. in the lunar base will help achieve partial food self-sufficiency and reduce the cost and risk of transporting food from the earth.

This time, it was also discovered that this type of hydrated mineral is rich in ammonium, which is a nitrogen fertilizer. We use ammonium bicarbonate on Earth. In addition, there is a small amount of potassium, which is a potash fertilizer. This discovery provides great possibilities for humans to grow crops on the moon in the future.

In the view of researchers, confirming the existence of water on the moon and estimating the amount of water is crucial to the planning and construction of the "Lunar Research Station" and "Lunar Village". The existence of this newly discovered water molecule also provides new ideas for the development and utilization of lunar resources, which may change the future development model of lunar resources.

Photo of ULM-1 single crystal

Figure source reference[1] Jin, S., Hao, M., Guo, Z. et al. Evidence of a hydrated mineral enriched in water and ammonium molecules in the Chang'e-5 lunar sample. Nat Astron(2024).

Cow and Sheep: Ah! The greenhouse effect? ​​Ah! Me?

We all know that the main gas that causes the global climate greenhouse effect is carbon dioxide. In addition to carbon dioxide, methane gas also plays a big role in the greenhouse effect.

Although methane gas is much less than carbon dioxide, its ability to absorb infrared rays is dozens of times higher than that of carbon dioxide, so it is also a factor that cannot be ignored.

So how is methane produced on Earth? You may not believe it, but the main source of methane comes from the farts of livestock such as cows and sheep.

Methane is produced in livestock because they rely on microorganisms in their stomachs to ferment the cellulose in food during the rumination process in order to digest the food.

One of these microorganisms, called Methanococcus, is very active. While helping cattle and sheep digest food, it also synthesizes a large amount of methane. These gases then enter the Earth's atmosphere through burping or farting.

Image source: pixabay

The content is compiled from China Science Popularization Expo Weibo, Science Academy, and Institute of Physics, Chinese Academy of Sciences

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