This is a diligent 'monkey' flying around the globe 15 laps a day, more than 40,000 kilometers in a circle. One day more than 600,000 kilometers are flying through the clouds. This is a 'monkey' It shoulders the Chinese dream of space science and catches the mysterious 'ghost' in the boundless universe - dark matter
On November 27, after more than 700 days of dark matter particle exploration satellite 'Goku' being emptied, the Dark Matter Satellite Group announced that 'Goku' has obtained the most accurate energy spectrum of TeV electron cosmic rays in the world at present and has directly measured the energy spectrum at 1 TeV (1 trillion electron volts) at the inflection point.
The chief scientist of the "Goku" satellite, Chang Jin, deputy director of the Purple Mountain Observatory of the Chinese Academy of Sciences, introduced the scientific achievements of the dark matter particle satellites.
Although we do not yet know what these results stand for, these results are beyond our expectations and may change the way we look at the universe. "Inch, director of science for China, said:" To scientists, This may mean a new astronomical phenomenon, of course, may also be the signal from the dark matter.
Cosmic ghost dark matter
Unveil the mystery of dark matter will be a revolutionary breakthrough in physics
Looking up at the bright sky, unknown forever. If you compare 21st-century modern physics and astronomy to a "clear sky," dark matter and dark energy are two dark clouds in the sky.
In the 1930s, Swiss astronomer Fritz Zweigji, who first proposed the concept of dark matter, found that galactic movements in large galaxy groups were very fast, but the direct gravitational forces in the galaxy cluster were far from enough to gather individual galaxies Together, he believes that in addition to the visible material in the universe, there should still be an 'invisible material' - a dark matter.
The latest cosmological observation shows that the universe is more like a three-part pie, accounting for only 4.9% of the common substances human beings are familiar with (that is, what the standard particle physics model can explain), and the remaining 95% Clear dark matter (26.8%) and dark energy (68.3%).
What exactly is a dark matter? A 'dark' word is a substance that is essentially 'invisible.' This invisible is not to say that it is invisible to the naked eye in the visible wave band, but even if it makes 'eighteen martial arts' In the past, any well-known detection means, such as infrared rays, ultraviolet rays, X-rays, etc. can not see it. The reason is simple: it does not reflect light or emit electromagnetic waves, and it is as mysterious as a ghost.
Although there has been no disappearance, scientists are convinced that revealing the mystery of dark matter will follow Copernicus's heliocentric theory. Newton's law of universal gravitation, Einstein's theory of relativity, and quantum mechanics are yet another revolution in physics Breakthrough.At that time, humanity will have a deeper understanding of the basic issues of material, space-time and the origin of the universe.
How to capture this "ghost" hidden in the darkness of the universe? At present, scientists mainly use three detection methods, direct detection, indirect detection and collider detection.
Direct detection, that is, detecting the signal generated by the collision of dark matter particles and ordinary nuclei, our country Sichuan Jinping underground laboratory is to take this method to detect dark matter collider detection, that is, by accelerating the two high-energy particle collisions on the accelerator to the dark matter particles Such as the Large Hadron Collider at the European Nuclear Center. "Indirect detection, which is to detect invisible dark matter particles by detecting the visible particles (ordinary particles) generated by the annihilation of dark matter particles." Dark matter satellite " Goku 'belongs to this category.
According to Fan Yizhong, deputy chief engineer of the Dark Matter Satellite Science Application System and researcher at Purple Mountain Observatory, if two dark matter particles collide and annihilate, they may produce high-energy positive and negative pairs of electrons that are easy to detect, high-energy gamma rays, protons or antiproton flows Such as high-energy cosmic rays.If you can accurately measure the energy spectrum of these particles, you may find the existence of dark matter clues, indirect evidence of the existence of dark matter.
'The core mission of' Goku 'is to look for evidence of the presence of dark matter particles in cosmic rays and gamma radiation and conduct astrophysical research,' said Bai Chunli, president of the Chinese Academy of Sciences.
'Eye-catching' exploration of space
Goku carries the heavy responsibility of finding out dark matter
Like "Journey to the West", the monk rescued Sun Wukong from the Five Fingers and gave him a new life. In reality, the birth of 'Wukong' is also inseparable from one person. He is the chief scientist of the Dark Matter Satellite, deputy director of the Purple Mountain Observatory Chang Jin.
More than 10 years ago, Chang participated in a long-period balloon experiment in the United States to observe high-energy electrons. In this experiment, they found a strange phenomenon: high-energy electron flow significantly exceeded the model in the energy range of 300 billion to 800 billion electron volts Estimated traffic.
These unknown high-energy electrons in the end is not generated by the annihilation of dark matter particles 'evidence', or from some celestial bodies, such as pulsars (that is, rotating neutron stars), supernova remnants, etc. This was the scientific community had caused an uproar, Too little relevant data, the confidence is not high, often can not be determined, but this discovery made him dreaming, 'If I can do a larger detector and put it on the satellite, perhaps We can judge whether this is a high-energy electron produced by the annihilation of dark matter. '
So, on December 17, 2015, the "Goku," carrying the ghost-like task of finding dark matter, has soared, and according to Fan Yi-chung, in space outside the Earth's atmosphere, despite its thinness, some High-energy particles, mainly protons, helium nuclei, etc., also contain a small amount of electrons. The positive and negative electron pairs generated during the annihilation of dark matter are likely to generate some special signals in the total energy spectrum of the cosmic rays. It is the primary scientific goal of 'Wukong'.
'' Wukong 'satellites have adopted a new method of detecting technologies for resolving the types of particles independently proposed by researchers at the Purple Mountain Observatory, Chinese Academy of Sciences, and have enabled economically applicable observations of high-energy electrons and gamma rays.' 'Wu Ji, director of the National Space Science Center of the Chinese Academy of Sciences Say.
This is indeed a breakthrough.As the Alpha Magnetic 2, for example, although it can be observed for a long time, but costly, cost about $ 2000000000. In contrast, the cost of about 700000000 yuanGuo Kong, to More affordable.
Of course, we can see clearly that the quasi-potential is the biggest 'selling point' of 'Goku' .As the world's widest range of observed energy range, the best energy resolution and the ability to identify the most powerful particle particle satellites, 'Goku 'Consists of a satellite platform and four payloads, namely a plastic flash array detector, a silicon array detector, a BGO energy gauge and a neutron detector, all of which together make up a high-energy particle telescope with the highest observable energy being the International Space Station' Alpha Magnetic '10 times the energy resolution of more than 3 times higher than similar international detectors.
What is the concept? Often called an analogy, like looking up to see two meters high basketball player, not only to see his body cells, you can also see the distribution of platelets inside.
New window of cosmic observations
Goku's electronic cosmic ray energy measurement range has significantly increased
'Performance is flawless!' Wu Ji was somewhat excited about the more than 700-odd days of 'Goku' traveling in space, saying that the orbital satellite has been in orbit for nearly two years and so far the performance of all detectors has been the same as that of the just launched, Maintain full status, there is no waste in the sky for a minute.
With an average of 60 high-energy particles per second and 5 million high-energy particles a day, Goku patrols around the clock, collecting about 2.8 billion high-energy cosmic rays, including about 1.5 million in the first 530 days of orbital operation Based on these data, researchers have successfully obtained the most accurate TeV electronic cosmic ray detection results of the world at present, and the results were released on November 30, this year (Beijing time) Published in the world's top journals "Nature" magazine online.
Chang Jin told Economic Daily that compared with the previous results, the energy measurement range of 'e-cosmic rays' of 'Goku' has significantly increased than that of foreign space exploration equipment and has expanded the window of human observation of the universe. Previously, no one above TeV Accurately observed in the sky At the same time, the measured 'purity' of TeV electrons is highest (ie the least amount of protons are mixed in) and the energy spectrum has a high degree of accuracy.
Even more surprising is that for the first time, Goku has directly measured the inflection of the electron cosmic ray spectrum at 1 TeV: the energy spectrum drops relatively gentle below 0.9 TEV, while the steepness is much higher.
'Although previous ground tests claimed that the inflection point was found, the data error was so great that the Fermi satellite did not see this inflection at the beginning of this year.' Goku 'directly measured this inflection.' Fan Yizhong explained that if dark matter Direct annihilation to positive and negative electron pairs results in a very steep cutoff in the spectrum, whereas astronomical models, such as the pulsar, give very smooth energy spectra, so it is critical to accurately measure the energy spectrum above 1 TeV.
'This inflection reflects the typical acceleration capability of high-energy electron radiation sources in the universe whose precise descending behavior plays a key role in determining whether dark matter is emitted by electronic cosmic rays with energies lower than 1 TeV.'
To the surprise of Chang et al., There appears to be a spire-like structure at 1.4 TeV, Fan said. Currently, Goku only collects more than a year of data and requires data of two to three years This spike structure is more specific as to whether it is dark matter or more detailed data, and their task now is to wait for more data from Goku, in addition to furthering the analysis.
As the great science fiction writer Isaac Asimov once said, the most exciting word that can be heard in scientific inquiry, the phrase that precedes the most important new discovery, is not Rica, I found it! 'But' well, it's weird! '
We look forward to seeing the 'Wukong' pierce the sky and use its golden eye to turn aside the cloud of darkness in the sky and give us a clearer universe.
Source: Economic Daily Author: Shen Hui
